Chapter 15: Maintaining Your Vegetable Garden

In This Chapter

Watering your plants

Mulching your vegetable garden

Understanding necessary soil nutrients

Feeding your vegetables

Staking and trellising plants

Controlling weeds

After planting your garden, you need to keep your vegetables growing vigorously until harvest. Maintaining your vegetable garden is similar to running a long-distance road race. After you're off and running, the key is to pace yourself for the whole race and not burn out in the beginning. Gardeners face a similar situation. You not only have to have lots of enthusiasm to prepare the soil and plant, but you also have to be consistent about checking plants, watering, weeding, fertilizing, and harvesting (among other tasks) to get the best results. If you lose interest in your garden halfway through the growing season, your harvest may be small or poor. Don't worry though; your garden won't require all your time — just some of it each week.

In this chapter, I tell you everything you need to know to keep your vegetables happy — including keeping your soil moist and fertile, adding mulch, supporting your plants, and keeping weeds at bay.

Introducing Your Inner Gardener to the Watering Basics

Even though Mother Nature is often very generous with rain, she still sometimes leaves gardens with a dry spell. Flooding isn't good for your garden, but neither is drought. If your plants don't have adequate water at the right times, they can easily die.

Different crops have different water needs. Some vegetables, like celery, are real water lovers and prefer to have moist soil around their roots at all times. Shallow-rooted crops (like onions and cabbage) need more careful watering during dry spells than deeper-rooted crops (like tomatoes) that can pull water from greater depths. Part II provides specific watering information for all the different vegetables.

You also need to keep in mind a plant's growth stage when watering. Here are some general watering guidelines for different growth stages:

Seedlings and germinating seeds: Seedlings with small root systems near the soil surface and germinating seeds benefit from frequent, gentle watering, which enables them to sprout and emerge quickly. Water once a day to a few inches deep if it doesn't rain. (Chapter 13 has more details on seedlings and transplants.)

Transplants: Water transplants when they're first planted in the garden and then every few days after that to 6 inches deep or so. Watering frequently helps the roots recover from transplant shock.

Established plants: Plants that have been in your garden for a few weeks and that are beyond transplant shock need to be watered deeply. Try to wet the soil at least 6 inches deep. Watering to this depth encourages roots to penetrate deeply, where they're less susceptible to drought. Give the soil a chance to dry out slightly (3 to 6 days if it doesn't rain) before watering thoroughly again.

When I tell you to water to a certain number of inches, don't feel like you have to guess when you've hit the mark; you can dig into the soil with a trowel to see how far the water has penetrated.

In the following sections, I explain when to quench your veggies' thirst and provide information on different watering methods. I also give you tips on how to conserve water.

Knowing when your veggies need a drink

In general, most vegetables use about 1 inch of water per week (1 to 2 inches in hot, windy, dry climates). If you don't get water from rainfall, you have to supply it. Here are some general guidelines for determining when your plants need water:

Your finger is the best indicator of when the soil has dried sufficiently to rewater. Dig down several inches into the soil; if the soil is dry to your touch 3 to 4 inches down, it's time to water.

Wilting plants can be a sign that your soil needs water. Wilting is when the leaves or stems of a plant droop, bend over, and look limp. These symptoms, however, can be misleading at times. Some plants, like tomatoes, peppers, and eggplants, tend to droop slightly during the heat of the day, even if the soil has enough moisture. If your plants don't stand tall and proud and the soil feels dry, add water and watch them perk up fast.

Overwatering also causes plants to wilt, so check the soil before watering. If the soil is waterlogged, roots die from lack of air. With fewer roots, plants can no longer take up the water they need from the soil, and so they wilt. Damage from insects and disease also cause wilting.

Each vegetable has a critical period when you need to be especially careful about watering. If you slack off during these times, your crop may be ruined. Table 15-1 shows the important watering periods for different types of vegetables.

Discovering ways to water your vegetable garden

You can water your vegetable garden several different ways. This section discusses some of the basic techniques, from the simplest — furrows — to the most complicated — drip irrigation systems.

You can measure water flow by attaching an inexpensive flowmeter (available at hardware and garden supply stores) to your outdoor spigot. To figure out the flow rate at the spigot, turn off all the spigots and read your water meter. Then turn on the spigot serving the hose line for 1 minute. Reread the meter to find out how much water flows through the hose in 1 minute. You need about 60 gallons per 100 square feet of garden to get 1 inch of water.

Furrows

Furrows are shallow trenches between raised beds that channel water to plant roots. This watering method is based on an old farmer technique of planting on narrow raised mounds or beds and then using furrows to water. The beds can be 1 to 3 feet apart — the wider apart they are, however, the more water you need to add. You can use a hoe to dig a furrow at planting time and then plant the seeds or transplants on top of the raised beds, in between the furrows.

When you're ready to water, fill the furrows completely with water and then wait a while, or fill them more than once so the water penetrates down as well as sideways into the raised soil. Poke around with your finger to make sure the water has penetrated the bed.

Furrows work best on level or slightly sloping ground; otherwise, the water moves too fast down the furrows without sinking in. This watering technique traditionally has been used in arid areas with clay soil, such as the Southwest, where little natural rain falls during the growing season and streams or ground water can be used in the garden. Furrows don't work well in sandy soil because the water soaks in before it can reach the end of the furrow.

Furrows aren't the most efficient way to water. Here are a few reasons:

It takes time for the water to run from one end of a mound or bed to the other.

The beginning of a row always gets more water than the end.

You have to move your hose around a lot to fill each furrow.

Water is wasted through evaporation as it's sitting in the furrow.

Basins

A basin is a donutlike depression around a vegetable plant that you fill with water — almost like a circular furrow. You make a basin in a 2-foot-diameter circle around the plant. Plastic basins that fit underneath plants such as tomatoes and eggplants are sold commercially. These basins concentrate the water around the roots of the plant.

Homemade basins work particularly well for watering sprawling plants like melons and squash early in the season. After the plants mature, however, their roots grow out of the diameter of the basin, and the method is no longer effective.

Hoses

Watering with a hose is probably the most common way that gardeners water. It's simple, and some might say therapeutic. Who hasn't seen a gardener after a long day at work come home and take some time to hose down the garden with a cup of coffee or drink in hand?

However, watering with a hose isn't the ideal watering system and probably is best for watering containers; for watering individual, large plants such as tomatoes; and when used in conjunction with the basin method (explained in the preceding section). In these situations, you can be sure that you're applying the right amount of water to your plants.

Unless you check the amount of water you're applying by digging the soil after watering, you may not water your garden evenly with a hose. Some areas may have lots of water, whereas other areas may just have water on the surface. Also, like overhead sprinklers (described in the next section), using a hose is a more wasteful way of watering because much of the water falls in pathways or on the lawn around your garden.

The best way to water your vegetable garden with a hose is to leave the hose running at a trickle in a basin near each plant until the water has soaked down at least 6 inches deep.

Sprinklers

A sprinkler, shown in Figure 15-1, is effective for watering vegetables planted in sandy soil that absorbs water quickly. It's also an effective way to water a large garden when you're pressed for time. Just set up the sprinkler, and based on the amount of time it takes to water to 6 inches deep (see the earlier section "Knowing when your veggies need a drink"), you can set a timer and go about other business. However, if you have heavy clay soil that absorbs water slowly or if your garden is on a slope, the water may run off and not sink into the soil where the plants need it. Instead, it's best to use drip irrigation (see the next section) so the water soaks into the ground.

For vegetable gardens, portable-type sprinklers (versus in-ground permanent sprinklers used in lawns) are best. You can move them around in your garden to cover a certain area or the whole garden. Some sprinklers throw water back and forth, whereas others send it in a circular direction. Choose the type that best suits your garden design.

Constantly wetting the foliage of vegetable plants can encourage disease problems. So when you use a sprinkler, water in the morning so the foliage can dry before nightfall and so you lose less water to evaporation.

As taller plants such as corn and tomatoes grow, sprinklers tend to be less effective because the water hits the foliage, damaging it and not thoroughly watering the rest of the garden. Some gardeners use watering towers that have an overhead sprinkler attached to the top. You position the sprinkler a few feet above the plants, hook it up to a hose, and sprinkle the garden. However, even these sprinklers prove to be less effective when plants reach above 4 to 5 feet tall. For these taller plants, it's best to choose one of the other watering methods described in this chapter.

Soaker-hose irrigation

A soaker-hose irrigation system consists of a rubber hose perforated with tiny pores that leak water, as shown in Figure 15-2. You can lay the hose between rows or curve it around plants, similar to how you use a drip irrigation system (described in the following section). Water leaks out of the hose and onto the soil, leaving your plant foliage dry and reducing evaporation.

Using a soaker-hose system is easier than using a drip irrigation system because it involves fewer parts and no nozzles. Its primary limitation is that it works best on flat terrain, often delivering water unevenly on sloped or bumpy gardens. It also may clog over time and not deliver water evenly along the hose.

Drip irrigation

A drip irrigation system provides water slowly through holes, or emitters, in flexible plastic pipes. Many different drip irrigation systems are available; they can consist of a single pipe with flexible lines running off it, or a series of pipes. You weave these pipes — which are connected to a water supply, a filter, and often a pressure regulator — along rows of plants so the water flows directly to the roots of your vegetables, as shown in Figure 15-3.

This watering technique is the most effective and efficient way to water vegetables because water drips right to the roots of the plants and little water is wasted on pathways, in between plants, and in between rows. Drip irrigation works well even if your garden is on a slope, which poses problems for most other systems.

The downside to drip irrigation is that it's more costly than the other methods listed in this chapter; it's also more involved to set up and take down at the end of the season. Drip irrigation is best for those gardeners who are into technology, who don't have lots of time to water, and who live in water-restricted areas.

You can wet an entire bed from one end to the other at each watering with drip emitters. You snap the emitters in the pipes wherever you want them, or you can buy a pipe with emitters already evenly spaced along the length of the pipe. The moisture radiates sideways underground and wets the soil between emitters.

As an alternative to emitters, you may want to use microsprinklers, which are tiny sprinklers that hook to plastic pipes like drip emitters. They're usually supported by 12- to 24-inch stakes and cover various-sized areas of soil with a fine spray of water. They're particularly useful for watering closely spaced vegetables like lettuce and root crops, or for watering germinating seeds.

Most nurseries sell drip irrigation systems, but you also can purchase them through the mail (see the appendix for details). Emitters and microsprinklers are available with different application rates, varying by the number of gallons applied per hour. Pressure-compensating emitters apply water consistently from one end of the line to the other, regardless of pressure changes due to uneven ground.

Follow these steps to set up a drip irrigation system in your garden:

1. Lay the pipe (or pipes — depending on the system) on top of the soil and cover the pipe with plastic mulch, or bury the pipe a few inches below the surface of the soil.

Most people like to keep the pipe close to the surface so they can check it for clogs and fix breaks.

2. If your pipe doesn't already have emitters in it, snap emitters in the pipe wherever you want them.

Position the emitters so they're close to the bases of your plants.

3. Run the drip system for at least several hours a day (2 to 4 hours).

Watch the system carefully the first few times that you water. Dig around in your garden to see how far the water travels over a given time period, and then adjust your watering schedule in the future.

If you live in an area where the soil freezes, don't leave your drip irrigation system or soaker hoses outside in the winter because they may burst. Instead, drain the water out, roll up the tubing, and store it in your garage.

Conserving water with a few handy tips

In many areas of the country, restrictions limit the amount of water you can use to grow your plants. If you're in one of these areas, it's especially important that you water smartly (though watering efficiently should be everyone's goal!). Sensible watering will save this precious resource and save you money.

Keep these water-saving pointers in mind when tending to your crops:

Grow plants that perform better under low water conditions. Some drought-resistant food crops you might try include herbs and hot peppers.

Plant veggies closer together. Doing so allows you to conserve soil moisture and shade the ground, keeping it cool and moist.

Consider the time of day that you water, especially if you use a sprinkler. You lose less water to evaporation (an important consideration in hot, dry climates) if sprinklers operate in the cool of the morning rather than during the heat of the afternoon. Watering in the morning also gives leaves a chance to dry off before evening; wet foliage is an ideal fungus-growing medium.

Frequent, shallow waterings do more harm than good. They cause roots to develop mainly in the upper few inches of the soil, where they're susceptible to drying out. Instead, go for occasional, deep waterings. Deep waterings allow moisture to penetrate deeply into the soil. The roots will follow the water, and the plant will be deep rooted and less likely to be effected by dry conditions. You'll water less frequently; maybe deeply once per week.

If your garden has heavy clay soil or is on a slope, and you find that water begins to run off before it penetrates 6 inches deep in the soil, try watering at intervals. Water for 10 to 15 minutes, let the water soak in for 15 to 20 minutes, and then water again.

Try to use soaker hoses and drip irrigation to direct water to the plants and not waste it on pathways. Use a timer to turn on the system during cool parts of the day for only as long as needed.

Collect rainwater from roofs and store it to be used in the garden. In some areas you can even use gray waste water from your home in your yards. Check with your local water municipality for regulations on using gray water.

For more ways to save water while maintaining your gardens and flower beds, check out Sustainable Landscaping For Dummies by Owen Dell (Wiley).

Keeping Your Plants Cozy and Weed Free with Mulch

Mulch is any material, organic or inorganic, that you place over the surface of soil, usually directly over the root zone of growing plants. It has many benefits depending on the type used. Mulch suppresses weeds, holds in moisture, modifies soil temperature, lessens the chances of certain diseases attacking your plants, and adds an attractive look to your garden.

Some people use compost as a mulch, but you have to remember that compost has a different purpose than mulch. Compost is added and mixed into the soil to add nutrients and increase the workability of soil (water-holding capacity, aeration, and so on). Mulch generally doesn't add nutrients, but it helps hold in the ones already in the soil and prevents undesirables from attacking your growing plants. (You can read more about compost in Chapter 14.)

You can choose from two basic types of mulch: organic and inorganic. For vegetable growers, each type of mulch has a unique purpose, as described in the following sections.

Spreading organic mulch

Organic mulch includes grass clippings, compost, leaf mold, pine needles, shredded bark, nut shells, cotton gin waste, straw hay, grain and fruit byproducts, composted manure, mushroom compost, peat moss, and sawdust. Some of these mulches are easier to find in different parts of the country. You can even use newspaper as an organic mulch; black-and-white newspaper print is perfectly safe to use in your garden, and most colored inks are soybean based and biodegradable (see Chapter 14 for more on using newspaper as mulch).

Generally, a 2- to 4-inch layer of organic mulch, spread evenly on the ground beneath your plants, is sufficient. However, you may have to replenish the mulch during the growing season, especially in hot summer areas, because many organic mulches break down quickly.

Using organic mulch in your vegetable garden has many benefits:

It conserves water by reducing the soil temperature and evaporation. It also keeps the soil cool by buffering direct sunlight.

It prevents wild fluctuations in soil moisture levels that can really spell disaster in hot weather.

It smothers weed seeds and prevents them from germinating. Any weeds that do come up in loose mulch are easy to pull.

As the mulch breaks down, it adds nutrients and improves the texture of the soil that it covers.

Organic mulch looks good and makes the ground tidy and clean.

The following list includes some of the downsides of organic mulches. As minor as they are, they may lead you to choose one type of organic mulch over another:

Bark mulches, such as pine, are quite acidic. So if you use them, keep a close eye on the pH level of your soil and correct it accordingly. (Chapter 14 tells you how to test soil pH.) Also, the latest trend is artificially colored mulches. I'd avoid these brightly colored mulches for your veggies, because they may contain potentially harmful chemicals that can leach into your soil. Choose natural bark mulches instead.

Grass clippings decay quickly and must be replenished often. Fortunately, grass clippings are usually pretty abundant. But if the grass goes to seed before you cut it, you may end up with grass growing in your vegetable garden. Also, make sure that no herbicides (weed killers) have been used on your lawn because the residue can damage or kill vegetables; if you have your lawn treated regularly, use another type of mulch. Likewise, hay mulch often has weed seeds in it, so use cleaner straw mulch if available.

Some organic mulches — such as fresh sawdust — rob nitrogen from the soil as they break down. You may have to add supplemental nitrogen to your vegetables if they grow mysteriously slow or start to turn yellow. (I discuss fertilizers in detail later in this chapter.)

Some organic mulches, such as peat moss or leaves, can pack down or get hard and crusty when exposed to weather. Water may not penetrate these mulches, running off the soil instead of soaking into the roots. My suggestion is to avoid peat moss; or at least mix it with another organic mulch such as sawdust. Don't forget that peat is also darn expensive.

Some lightweight mulches, like straw or cocoa hulls, can blow around in the wind. You may want to avoid them if you live in a windy area.

Organic mulch, which keeps the soil cool, may slow the growth and maturity of warm-season crops such as tomatoes and melons. This cooling can be especially problematic in areas with cool summers. However in very hot-summer areas of the country, organic mulches work to keep the roots of even warm-season crops cool and healthy.

Composted manures may burn young vegetables if used as mulch because the manures vary in the amount of nitrogen they contain. If you want to use composted manure, mix it with three times the volume of another organic mulch before applying it.

You can purchase organic mulches like shredded bark, compost, and leaf mold in bags or sometimes in bulk from nurseries and garden centers. Grass clippings, compost, and wood chips come free from your yard or garden.

Laying inorganic mulch

Inorganic mulch includes things like plastic, landscape fabric, and believe it or not, old carpet. I explain how to use all types of inorganic mulches in the following sections.

Plastic

Plastic is the most-used inorganic mulch for vegetable gardens. Mulching with plastic (see Figure 15-4) works best when you install drip irrigation or a soaker hose underneath the plastic before planting. Otherwise, watering is difficult. (You can place the irrigation on top of the plastic, which enables you to more easily check for clogs, but you have to run individual emitters to each plant.) Plastic doesn't work well with vegetables planted very close together, such as root crops.

The color of plastic mulch you use depends on what you're growing. Some vegetables grow better with certain colored plastics. For example:

Tomatoes, eggplants, and strawberries grow best with red plastic mulch.

Melons grow well with dark green or IRT (infrared transmitting) plastic mulch.

Peppers like a silver-colored mulch.

White plastic is good for hot climates where you want to stop weeds from growing but not heat up the soil.

Black plastic is good for weed control and warming soils. It can be used on many vegetables including cucumbers and squash.

To mulch with plastic, follow these steps:

1. Purchase rolls or sheets of 2- to 4-millimeter plastic (the thicker the better).

You can find the thickness of the plastic on its label. Purchase plastic at garden centers or hardware stores, or check the appendix for sources of various colored mulches.

2. If you're using irrigation under the plastic, lay down your drip irrigation and turn it on for several hours.

Note where the wet spots are in the soil. Adjust the drip hose so water doesn't pool in certain areas, but is evenly distributed. See the earlier section on drip irrigation for more details on installing this type of watering system.

3. A week or two before planting, water the entire area with a hose or sprinkler so it's wet to 6 inches deep.

Roll out the plastic over the planting area and cover the edges of the plastic with soil.

4. Cut holes in the plastic where you want to plant your transplants.

You can sow seed this way as well; just make sure that the seed can get through the holes in the plastic after it germinates.

5. Plant your seeds or transplants in the holes.

Make sure you plant in wet spots; otherwise, the plants may not get enough water.

If you live in a climate that gets very hot in the summer (Texas, for example), after the weather starts to warm, you may want to cover black plastic with an organic mulch to prevent the soil from getting too warm. Or consider using white plastic instead.

Unless you have a problem with the irrigation system, you usually don't have to remove the plastic until the end of the season.

Other inorganic mulches

Beside plastics, you also can use the following inorganic mulches in your vegetable garden:

Cardboard: Even though it's biodegradable, cardboard takes so long to decompose that I treat it as an inorganic mulch. You can cut cardboard boxes to fit in pathways. If you don't like their look, cover them with hay or straw.

Landscape fabric: This inorganic mulch doesn't warm the soil as much as black plastic, but it's permeable, enabling you to water through it. It also does a good job of keeping down weeds. You can find landscape fabric at your local nursery. You apply landscape fabric the same way that you do plastic (see the preceding section).

Rug strips: Roll out 3-foot rug strips and place them nap side down, leaving about 6 inches of open soil between strips for irrigation and planting. Even though rug strips look pretty weird in a garden, they keep the weeds down and make a nice path.

Deciding which mulch to use

Choosing a mulch and deciding when to use it in your vegetable garden depends on the type of vegetables that you grow and when you plant them. Check out these mulching tips for different types of vegetables:

Cool-season vegetables planted in early spring: You want the sun to warm your soil in the spring because lots of sun helps young plants get off to a fast start. Here are a few mulching pointers for these vegetables:

• Lay down organic mulch when the soil starts to warm and when the plants need regular water. If you mulch too early, the soil stays too cold and wet for proper root growth.

• In areas with short growing seasons, you can plant broccoli, cauliflower, and cool-season plants through plastic. Cover the plastic with organic matter when the weather warms to keep the soil cool.

Cool-season vegetables planted in late summer or early fall: With these vegetables, you want the cooling effect, so put down an organic mulch right after planting. Here are a few other things to keep in mind:

• When the weather starts to cool, rake off or remove the organic mulch so the soil warms.

• You can plant through plastic late in the year, but you should cover it with an organic mulch immediately so the soil doesn't get too hot. Then remove the organic mulch when the weather cools and let the plastic warm the soil through harvest.

• Many root crops can be stored in the ground well into winter if you cover them with a thick organic mulch like straw. Applied before the ground freezes, the mulch keeps the soil loose and unfrozen so you can dig the vegetables later into winter.

Warm-season vegetables planted in spring: With these vegetables, keep the ground clear if you're planting really early — the more heat the better. Planting through plastic works in early spring. In hot climates, apply an organic mulch when the weather starts to get really warm in summer.

Determining Important Nutrients Your Soil Needs

Sixteen elements are essential for healthy plant growth. Of these elements, plants especially need carbon, hydrogen, and oxygen in large quantities. They also need energy from sunlight for photosynthesis, the process by which plants use carbon dioxide from the air and water from the soil to produce sugars that enable them to grow. Nature — and your conscientious watering — supply these elements.

Plants also need nitrogen, phosphorus, and potassium in relatively large quantities. Plants take up these three nutrients — often called macronutrients — from the soil. If your soil doesn't contain enough of these nutrients, you can supply them by fertilizing, which I discuss in detail later in this chapter.

The following sections list important nutrients that your plants need, along with information to help you determine when you need to add nutrients to your soil. To find out what quantities to add, refer to the chapters on individual vegetables in Part II. (Chapter 14 has details on soil pH and pointers on performing soil tests.)

Macronutrients

Nitrogen (N), a key component of proteins and chlorophyll (the plant pigment that plays a vital role in photosynthesis), is responsible for the healthy, green color of your plants. Nitrogen is a volatile creature; it easily moves around in the soil and can leach away from plant roots as a result of rain or watering. Therefore, you need to be sure that your plants receive a steady supply of nitrogen all season long.

How to detect too little: Plants with a nitrogen deficiency usually show yellowing (in older leaves first) and slowed growth. However, with plants like tomatoes, a nitrogen deficiency may first appear as a reddening of the stems and the undersides of the leaves.

How to detect too much: A plant with too much nitrogen has soft-textured, dark green foliage and an underdeveloped root system, and flowering and fruiting are delayed. Too much nitrogen fertilizer, especially when plants are young, can actually burn the roots and kill them. Because nitrogen leaches out of the soil quickly, if you have too much, stop fertilizing, wait, and eventually the problem will solve itself.

How to add it to your soil: You can supplement soil nitrogen by adding organic fertilizers, decomposing organic matter, or composted manure.

Phosphorus (P) helps promote good root growth, increased disease resistance, and fruit and seed formation. It's less available in cooler soils, so adding a fertilizer containing phosphorus in spring is a good idea.

How to detect too little: Plants lacking in phosphorus are stunted and sport dark green foliage and purplish stems and leaves (on the older leaves first). Soil pH affects the availability of phosphorus to plants; a pH of 6 to 7.5 keeps it available.

How to detect too much: Too much phosphorous is a problem because it can cause zinc and iron deficiencies, and it can leach out of the soil and pollute streams and lakes. Signs of zinc or iron deficiencies appear as discolored or poorly formed leaves and reduced growth and production.

How to add it to your soil: Sources of phosphorus include minerals, organic matter, inorganic fertilizers (such as rock phosphate), and organic fertilizers (such as bone meal).

Unlike nitrogen, phosphorus doesn't move quickly through soil. So, add a fertilizer containing phosphorus to the root zone before planting (instead of sprinkling it on the soil surface).

Potassium (K) promotes vigorous growth and disease resistance.

How to detect too little: The first sign of a deficiency is slowed growth; brown leaf edges and deformed yellow leaves can indicate a severe deficiency.

How to detect too much: Too much potassium can create nutrient imbalances in the plant and stunt its growth.

How to add to your soil: Soil minerals provide potassium, as do organic matter and inorganic fertilizers, such as green sand and granite dust.

Secondary nutrients and micronutrients

Calcium, magnesium, and sulfur are known as secondary nutrients. Plants need them in substantial quantities, but not to the same extent that they need nitrogen, phosphorus, and potassium.

How to detect too little: Most alkaline soils contain these secondary nutrients naturally, and few soils are deficient in sulfur. Most home garden soils contain these nutrients. But if you've eliminated other possibilities and you suspect a problem, a soil lab can do tests on your plant leaves to detect any deficiencies.

How to add them to your soil: In regions where the soil is acidic, liming to keep your soil's pH in a good growth range provides adequate calcium and magnesium (the latter if you use dolomitic limestone). See Chapter 14 for more on liming.

Micronutrients (iron, manganese, copper, boron, molybdenum, chlorine, and zinc) are elements that plants need in tiny amounts. Too much of one of these elements is often as harmful as too little.

How to detect too little or too much: A micronutrient deficiency or excess may mean that your soil is too acidic or too alkaline, so you can correct the problem by changing the pH rather than by adding more nutrients. Deficiencies and excesses most often are noted on plants that are growing poorly and through soil tests.

How to add them to your soil: Sometimes, changing the pH sufficiently to increase micronutrient levels isn't practical, or you may need to give a plant a micronutrient quickly while you try to change the soil pH. In such cases, micronutrients are applied as chelates. Chelates are added to other chemicals, in this case micronutrients, to keep them available to plants when soil conditions are unfavorable. Apply chelated micronutrients to your soil, or better yet, spray them on plant foliage.

Fertilizing Your Vegetable Garden

Even if you have the healthiest soil around, growing vegetables is an intensive process that strips many important nutrients from the soil. So you need to add some fertilizer to your soil to keep it in optimum shape to feed your plants.

How much fertilizer you add depends on the soil and the plants you're growing. So it's difficult to generalize across the board on what type of fertilizer to choose and how much to apply. Soil tests are a great way to know what to add. Refer to Chapter 14 for more on soil tests.

Examining a fertilizer label

Commercial fertilizers are labeled with three numbers that indicate the fertilizer's nutrient content (see Figure 15-5). The first number indicates the percentage of nitrogen (N), the second number shows the percentage of phosphate (the type of phosphorus, P2O5), and the third number represents the percentage of potash (the form of potassium used, K2O). (I explain these nutrients in detail in the earlier section "Macronutrients.")

For example, a 5-10-5 fertilizer contains 5 percent nitrogen, 10 percent phosphate, and 5 percent potash, and it's called a complete fertilizer because it contains some of each type of nutrient. In contrast, bone meal has an analysis of 4-12-0. It's a good source of phosphate but doesn't provide any potash. The other materials in a commercial fertilizer that the analysis numbers don't account for are generally filler — unimportant materials that add bulk to the bag so the fertilizer is easier to spread.

How much fertilizer do you use? Soil tests are the best way to correct deficiencies (see Chapter 14 for details), but fertilizer bags also give general dosage recommendations for gardens. Most fertilizer recommendations for maintenance fertilization (rather than to correct a deficiency) are made according to how much nitrogen a crop needs. So, for example, if you have a recommendation for 3 pounds of 5-10-10 fertilizer per 100 square feet, but the fertilizer that you have on hand is 5-5-5 fertilizer, apply 3 pounds of 5-5-5. Even though the 5-5-5 fertilizer's percentage of phosphate and potash is less than that of the 5-10-10, it offers the same recommended amount of nitrogen.

Choosing a fertilizer

Most home gardeners can grow a perfectly beautiful and productive garden using organic principles. In the last 20 years, an explosion of organic products (such as fertilizers) has hit the market, making gardening with this method much more accessible. I choose to garden with organic fertilizers, and I explain why in this section; I also warn you of the dangers of chemical fertilizers.

Organic fertilizers

Organic fertilizers — animal and green manure, blood meal, fish emulsion, cottonseed meal, granite dust, and rock phosphate — have several advantages:

Many organic fertilizers contribute organic matter to your soil, improving its structure, feeding soil microbes, fighting fungal and bacterial diseases, and contributing micronutrients.

Most organic fertilizers supply a slow but steady diet for plants.

Some organic fertilizers, such as manure and compost, may be inexpensive — or free if you create them yourself.

Complete organic fertilizers, such as 5-5-5, are now more widely available and have higher concentrations of nutrients than in the past, making them easy-to-use alternatives to chemical fertilizers.

However, it's not all sun and roses when using organic fertilizers. Here are some disadvantages:

Some organic fertilizers, such as manures and compost, are bulky and difficult to store and transport.

Their slow release of nutrients, in some cases dependent on the action of soil microorganisms, may take too long to remedy a dire situation when an adequate nutrient supply is needed.

Many organic fertilizers are lower in nutrient content than their chemical equivalents, and the contents may vary depending on the weather and conditions where the fertilizers were produced. So you may not be exactly sure how much to put on your garden.

Chemical fertilizers

Chemical fertilizers are synthetically manufactured. They include elements such as sodium nitrate, potassium chloride, and superphosphate. Chemical fertilizers come in liquid, granular, powder, or pellet form. You can fertilize when you water with a watering can, using a liquid fertilizer. Or you can sprinkle some granular fertilizer around each plant.

Chemical fertilizers are widely available, less expensive than organic fertilizers, quick acting, and easy to use, but I believe that the disadvantages of using chemical fertilizers far outweigh the advantages. Here's why:

Chemical fertilizers add no organic matter to your soil and contribute nothing to improving soil structure. In fact, some research suggests that chemical fertilizers actually harm the microorganisms in the soil, making the soil less able to support long-term plant growth.

Chemical fertilizers are concentrated and fast acting, but they have no long-term benefits for your soil. It's like taking a vitamin for your health versus eating a good meal.

Manufacturing chemical fertilizers requires large amounts of energy, usually supplied by nonrenewable resources. This massive use of energy increases pollution, global warming, and our carbon footprint. Even though some commercial organic fertilizers, such as rock phosphate and green sand, also are manufactured and require energy inputs, home gardeners can instead choose to use locally made compost and manures to get the nutrients they need for their gardens.

Side-dressing

Depending on the crops you grow and the type of soil you have, you may need to add repeat doses of fertilizer throughout the growing season — a practice called side-dressing. For example, because sandy soils don't hold nutrients well, giving plants small, regular fertilizer applications ensures a steady supply of nutrients.

In the following sections, I describe specific fertilizers and methods that are best for side-dressing and explain how frequently you should side-dress your veggies. For information on fertilizing vegetables growing in containers, see Chapter 18.

Fertilizers and techniques that work well for side-dressing

Granular organic fertilizers, such as 5-5-5, are a good choice for side-dressing most root and fruiting crops. Use 1 to 2 tablespoons per plant, or 1 to 2 pounds for every 25 feet in a row.

Depending on plant spacing, side-dress either in a narrow furrow down a row or around each individual plant (refer to Figure 15-6). In either case, spread granular fertilizer (which is easier to use than liquid fertilizer) at least 6 to 8 inches away from plant stems. Rake the fertilizer into the soil and then water.

For leafy green crops, fish emulsion is a quick-acting, highly soluble organic source of nitrogen that gives your greens a boost, especially if they're turning a pale green color. You can add micronutrients to this fertilizer by mixing it with seaweed. Add this liquid fertilizer to your watering can following the directions on the label. As you water, pour this solution around the bases of the plants and on the leaves.

Knowing when to side-dress

Too much fertilizer can be more harmful than too little. Excess fertilizer accumulates in the soil in the form of salts and damages plant roots. So be sure that growing conditions enable plants to use the fertilizer that you apply. For example, don't add fertilizer during a dry spell if you can't irrigate your garden, because without adequate soil moisture, roots can't take up nutrients. And if cool weather causes your plants to grow slowly and need less fertilizer, go easy on the fertilizer until the temperature warms up or you'll be wasting it.

The kind of plants that you grow makes a difference in how often you side-dress. Plants that take a long time to mature (such as tomatoes and eggplants) and heavy feeders (like corn) generally benefit more from side-dressing than quick-maturing crops that fix their own nitrogen — such as lettuce, or legumes like peas and beans. See Table 15-2 for some general side-dressing guidelines.

Give 'Em Something to Lean On: Supporting Your Vegetables

Some vegetables, like peas and beans, have climbing habits that require some type of support to grow on. Other vegetables — including tomatoes, cucumbers, and even melons — have sprawling habits that benefit from some type of staking or support. Staking plants, tying them to a trellis, or growing them inside wire cylinders reduces disease problems because it allows for better air circulation and keeps the fruits off the ground where they may be attacked by bugs or become sunburned. (Fruit skins get sunburned due to sudden exposure to strong sun and eventually rot.) Supported plants also are easier to harvest and require less space to grow (they go up instead of out).

Figure 15-7 shows some techniques for supporting vegetables, but you can find more in Chapter 16. In the following sections, I provide some suggestions for supporting different types of vegetables.

Beans and peas

Twining or clinging plants like beans and peas grow best when they're supported by some type of string trellis. I like to use an A-frame string trellis, which enables me to grow plants on both sides, but single poles are fine, too. Making an A-frame string trellis is easy; just follow these steps:

1. Using at least six 2-by-2-inch redwood or cedar stakes, build two 6-by-6-foot squares.

Redwood and cedar stakes are naturally rot resistant and good choices.

2. Secure the corners of the squares with metal corner braces and connect the two squares on one side with sturdy hinges.

The hinges enable you to easily move or store the trellis.

3. Hammer small nails at 2- to 4-inch intervals along the top and bottom of the trellis.

Don't pound the nails in all the way; leave about 1 inch sticking out.

4. Weave some sturdy twine or string up and down the trellis, between the nails.

Bingo; you have an A-frame string trellis.

Handmade wooden teepees are a great way to support your beans, and kids love them because they're great places to hide. Here's how to construct your own teepee:

1. Using four to six 2-by-2-inch redwood or cedar stakes that are 6 to 8 feet long, form a conelike teepee.

2. Tie the stakes together with twine at the top of the teepee.

3. Run some string or twine around the bottom of the teepee, securing the string or twine at each stake with a small nail.

4. Run more string back and forth around the stakes, from the top of the teepee to the bottom, leaving several inches between each run.

Leave one side of the teepee open so your kids can get inside, and then plant beans around the base of the teepee. In time, the beans will cover the trellis, creating a great fort for your kids.

Melons and cucumbers

You can plant bush varieties of melons and cucumbers inside small (2- to 3-foot-high) wire cylinders similar to those used for tomatoes (see the next section). But for more vigorous varieties, I like to use a sturdier version of the A-frame trellis that's used for beans and peas (see the previous section). Instead of using string, I cut 6-foot-by-6-foot pieces of hog fencing (it has 6-inch squares) and nail them to each side of the trellis. The wire provides better support for heavy fruit (like melons) than string does, and the wide-open fencing doesn't constrict the growth of the fruit (so you get straighter cucumbers). You can purchase hog fencing at agricultural stores.

You also can grow melons on a trellis. Choose small-fruited varieties of watermelon or any variety of cantaloupe, and plant your seeds at the base of the trellis. Tie the vines to the trellis as they grow. After a fruit forms, slip the leg of an old nylon stocking over the fruit, tying the bottom of the stocking in a knot. Then tie the other end of the stocking to the wire trellis so that the fruit is supported. As the melon grows, the stocking expands and supports the fruit, which may break off otherwise. Flip to Chapter 8 to see how this support system looks.

Tomatoes

You can support tomato plants several different ways:

Tie them to stakes, which you pound in the ground next to the plants.

Grow them inside wire cages, which you can buy at nurseries or easily build yourself out of hog fencing.

If you're growing indeterminate varieties, which keep growing and producing fruit all season, choose or build cages large enough to support the huge plants that will grow. Also be sure to secure them to the ground well so they don't blow over during a summer thunderstorm. (You can read more on indeterminate tomatoes in Chapter 4.)

Construct string or wire trellises, like you do for beans and peas.

Fighting Weed Wars

A weed is any plant that's growing where you don't want it to. Some weeds are worse than others, but in general, you don't want any weeds in your vegetable garden because they compete with vegetables for light, water, and nutrients. If you have a lot of weeds, you'll have weaker plants and a less substantial harvest. Besides, weeds look terrible.

The key to battling weeds is to get to them early before they're firmly established. When they're young, weeds are easier to pull, easier to till under, and less likely to produce seeds that cause problems down the road. In the following sections, I show you how to fight weeds before and after you plant your veggies.

Making a preemptive strike on weeds

You can reduce weeds in your vegetable beds many different ways. Here are some things that you can do before planting your garden:

Presprout weed seeds. Presprouting — forcing weed seeds to germinate before you plant so you can kill them early — really cuts down on the number of weeds in your beds. Follow these steps:

1. Prepare your planting bed several weeks before you're ready to plant.

Refer to Chapter 3 for details on planning and preparing your beds for planting.

2. Water the soil well and wait a few days.

Presto, young weeds begin popping up.

3. Kill the weeds.

You can choose to kill the weeds one of two ways: pull them out by hand, or rake the bed lightly to uproot the seedlings and then let them dry out to die.

However you get rid of the young weeds, disturb the soil as little as possible when you do it; otherwise, you'll bring more seeds to the surface.

Plan for easy weeding. Leave enough room between rows so you can weed the soil easily.

Solarize the soil. When you solarize the soil, you use the power of the sun to kill weeds. This technique works best in the middle of summer in hot climates like Arizona and Florida. The only downside to solarizing is that it takes a while. Follow these steps to solarize your soil:

1. Prepare your bed for planting and water it well.

2. Dig a 6-to-12-inch-deep trench around the perimeter of the bed.

3. Cover the entire bed with thick clear plastic (4 millimeters) and place the edges of the plastic in the trenches and fill the trenches with soil. Then wait.

The temperature gets so hot underneath the plastic that it kills insects, disease organisms, and weeds. It usually takes a few months of solarizing to get a beneficial effect.

Plant your vegetables at the proper time of year. That way they get off to a fast start, and weeds have a harder time catching up with them. See Chapter 3 for details.

Battling weeds after planting

If you come across weeds after you plant your crops, you have several choices for eliminating them:

Mulch your beds. Applying a layer of thick organic mulch is one of the best ways to battle weeds. Even if mulch doesn't smother the weeds and their seeds, the weeds that do come up are easy to pull. Planting through plastic is also an effective way to keep weeds from becoming a problem. See the earlier section "Keeping Your Plants Cozy and Weed Free with Mulch" for more information.

Pull the weeds by hand. While they're young, weeds come out of the ground easily. Get 'em roots and all, whenever you see them. If you can't pull out the roots by hand, use a trowel.

Cultivate the soil. Simply hoeing or lightly turning the soil between vegetables exposes the weeds' roots and kills many of them. Cultivating is most effective when it's done often (a few times a week in the first month or so of gardening) and early when the weeds are small. Some cultivating tools are designed especially for this purpose; see Chapter 20 for details.

Keep garden paths clean. Try to keep your garden paths as weed free as possible; otherwise, weeds will creep into your planting beds. Try covering the paths with a thick mulch to keep weeds from becoming established.

Make sure the areas around the garden are weed free. If you're growing vegetables near a field or weedy woodland edge, try to mow a wide strip between your garden and the field so the weed seeds can't blow in as easily. It won't stop all of them, but every little bit helps.