Chapter 4: Tomatoes: The King of Veggies

In This Chapter

Choosing the right variety for your garden

Growing your tomatoes to perfection

As I mention in Chapter 2, tomatoes are hands down the most popular vegetable grown in the garden. After you've picked and tasted a juicy, vine-ripened fresh tomato, you'll understand why. You can't compare the bland supermarket tennis balls that most people make do with to the taste and texture explosion of the homegrown tomato. The best news is that tomatoes are even easy to grow! Just give them a good start and a little attention during the growing season, and you'll be rewarded with more delicious ripe fruits than you can eat.

Tomatoes are no longer limited to the round red fruits we're accustomed to seeing. Through breeding and the rediscovery of heirloom varieties, tomatoes now come in almost every color of the rainbow, from black to white, and in a variety of sizes, from as tiny as a blueberry to as large as a grapefruit. Modern breeding practices have created tomato varieties that are well adapted to heat, cold, and even containers. Great taste, disease resistance, and ease of growing make tomatoes the most rewarding to grow of all the vegetables.

Even though we all call the tomato a vegetable, botanically it's considered a fruit. Any edible plant part that develops from the ovary of the plant (found behind the flower) after fertilization is considered a fruit, so tomatoes, cucumbers, squash, peppers, and eggplant are considered fruits; lettuce, carrots, onions, and spinach are technically considered vegetables. Of course, this discussion is a moot point, because most folks categorize fruits and vegetables by their uses, not by their botany. (Case in point: A Supreme Court ruling in 1893 declared the tomato a vegetable.) So be it.

Checking Out Tomato Varieties

Before deciding which tomato variety to grow, you first need to consider the growth habits of the different plants. Plants can grow into huge monsters or tiny pot plants. So first decide how much room you have to plant tomatoes, and then decide on the right variety for that space. Whether a cherry tomato, paste tomato, or red slicing variety, tomatoes all fall into one of these categories:

Indeterminate: Indeterminate tomato plants keep growing and growing and growing. The side branches and shoots continue to grow even after fruit is set (in other words, after the flower has been pollinated and the young tomato fruits begin to grow), and they can be stopped only by frost, insects, disease, or an ax. Most main crop tomatoes are of this type.

These tomato varieties do produce a ton of fruit, but the tomatoes tend to mature later in the season than those born by the shorter plant varieties. Varieties such as ‘Better Boy' and ‘Brandywine' are good examples of indeterminate tomato types.

Determinate: Unlike indeterminate varieties, determinate varieties tend to stop growing once the shoots set fruit. Varieties vary in the degree that they're determinate, but these plants generally tend to be shorter and produce less fruit. However, they do mature fruit earlier than indeterminates. Varieties such as ‘Solar Fire' and ‘Oregon Spring' are good examples of determinate types.

Dwarf: These stronger determinate plants tend to reach only a few feet tall, produce all of their fruit at once, and then stop producing for the season. These plants are excellent as patio or container plants, producing cherry tomato-sized fruits. The ‘Patio' and ‘Tiny Tim' varieties are examples of dwarf tomatoes.

Dwarf-indeterminate: The best of both worlds, these plants stay dwarf, only reaching about 3 to 4 feet tall, but continue to produce full-sized tomatoes all season long. They grow well when planted in containers or in the garden. Some dwarf-indeterminate varieties include ‘Bush Big Boy' and ‘Husky Gold'.

In Figure 4-1, you can see the differences between determinate, indeterminate, and dwarf plants.

When in doubt about a variety's quality, look for the All-America Selections (AAS) winner label in the variety's description. This group evaluates new varieties yearly by conducting trials all across the country for outstanding growth and flavor. A variety with this label will likely perform well in your garden.

Tomato varieties also can be classified as hybrids or open-pollinated plants (see Chapter 3 for more information):

Open-pollinated refers to varieties that have the ability to cross-pollinate among themselves naturally and produce plants that resemble the parents. All heirlooms are open-pollinated and are generally considered varieties that were grown prior to the 1940s.

Hybrid varieties are the products of crosses between two varieties that wouldn't necessarily naturally cross. Hybrids are an invention of post-World War II plant breeders to make varieties more productive, uniform, and disease resistant.

One more way to classify tomatoes is by their color, shape, and use:

Color: What was once exclusively a red fruit now comes in orange, yellow, green, black (really dark brown), white, and striped colors. The only color not represented is blue; however, give breeders a little time, and it may show up someday!

Shape: Tomatoes have been traditionally available as a round fruit, but new shapes pop up all the time. Some shapes that are available today include oblong, egg, cherry, grape, pear, and flattened.

Use: While I mostly like to eat tomatoes fresh off the vine, some varieties are better suited to sauces, canning, and drying. (Check out the later section "Studying some saucy tomatoes" for more on varieties that are great for processing.)

With so many distinctions, how do you decide which varieties to plant? In this section, I help you decide by listing some of my favorites.

Enjoying classic red, round tomatoes

When you say the word "tomato," most people think of red, round tomatoes. They're the classic, bright red, juicy, meaty tomatoes that we all want to grow. You have hundreds of varieties to choose from, so deciding can be difficult. But, don't worry! The following list includes some of my favorites that you may want to try:

‘Better Boy': This hybrid indeterminate produces smooth 8- to 12-ounce fruits 72 days after transplanting that are great for slicing. This variety has good disease resistance.

‘Big Beef': This All-America-Selections-winning, indeterminate hybrid is loaded with disease resistance, producing blemish-free 8- to 10-ounce fruits. This variety matures 70 days from transplant.

‘Bush Big Boy': This hybrid dwarf-indeterminate variety produces 10-ounce fruits on a 4-foot-tall plant 71 days after transplanting.

‘Cold Set': If you're trying to grow tomatoes in a cold climate, try this open-pollinated variety. The 4- to 6-ounce fruits set 65 days after transplanting on determinate plants that can tolerate a light frost.

‘Costoluto Genovese': This Italian indeterminate heirloom is close to my heart and taste buds. The 8-ounce fruits are deeply ribbed, juicy, and have a strong tomato flavor. The plants love the heat and produce fruits 80 days after transplanting.

‘Delicious': If you want to grow "the big one," this indeterminate heirloom is for you. The plant produces fruit 77 days after transplanting, and those fruits often weigh more than 2 pounds each. This variety holds the world record for the largest tomato: 7 pounds, 12 ounces.

‘Early Girl': Despite being an indeterminate hybrid (which generally matures later in the season), this plant produces 4- to 6-ounce fruits only 52 days after transplanting. You can experiment with the ‘Bush Early Girl' version as well, which has the same characteristics except that it only grows 2 feet tall.

‘Oregon Spring': This determinate, open-pollinated variety is bred for cold tolerance and relatively few seeds in each fruit. The 7- to 8-ounce fruits are produced only 58 days after transplanting.

‘Solar Fire': This determinate hybrid was bred at the University of Florida, so it's heat tolerant. The large, 7- to 10-ounce round fruits are disease resistant and mature 72 days after transplanting.

‘Stupice': This Czechoslovakian indeterminate heirloom is an early and cold-tolerant variety that bears 1- to 2-ounce fruits 52 days after transplanting.

‘Super Bush': This determinate, 3- to 4-foot tall hybrid plant is great in containers. Unlike many other container-adapted varieties, the ‘Super Bush' variety produces large, 8- to 10-ounce fruits on disease-resistant plants. Fruits are produced 85 days after transplanting.

When in doubt about choosing a variety to grow in your garden, ask your local garden center, farmer's market, or neighbor who's growing tomatoes for suggestions about what grows best in your region.

Surveying all the other colors of tomatoes

Tomatoes of a different color (other than red that is) are very popular. The flavor of many of these varieties is comparable to the red varieties, but the colors can be outstanding in salads and casseroles, or just by themselves. Here are some beautifully colored varieties you might try:

‘Black Krim': This indeterminate Russian heirloom has unique, 12-ounce, dark reddish-brown fruit. Both the skins and the flesh are colored this way, and the fruit color darkens in hot weather. Fruits are produced 80 days after transplanting. This tomato is something really different!

‘Brandywine': This Amish indeterminate heirloom has unique potato-leaf foliage and produces 1- to 2-pound pink fruits with red flesh — reportedly the most flavorful of all varieties — 80 days after transplanting. You also can buy a similar ‘Yellow Brandywine' and ‘Red Brandywine' if you'd like all the colors of ‘Brandywine' tomatoes in your garden.

‘Cherokee Purple': This heirloom indeterminate bears 10-ounce dusky rose- or purple-colored fruits with thin skins about 80 days after transplanting.

‘Great White': This indeterminate heirloom plant produces 10- to 12-ounce white-colored fruits 85 days after transplanting. The meaty fruits, whose skins and flesh are white, have a mild flavor, few seeds, and a creamy texture. When combined with ‘Black Krim' it makes an interesting black-and-white tomato salad.

‘Green Zebra': These 3-ounce fruits are produced 75 days after transplanting. The skin and flesh are green even when ripe. The flavor of this indeterminate heirloom is tangy and sweet and makes a mean fried green tomato dish.

‘Husky Gold': This AAS-winning dwarf-indeterminate hybrid plant only reaches 4 feet tall, but it produces deep golden-colored, 8-ounce fruits 70 days after transplanting.

‘Lemon Boy': The first lemon-yellow-colored tomato, this hybrid indeterminate produces 7-ounce fruits with lots of disease resistance 72 days after transplanting.

‘Long Keeper': These determinate, open-pollinated plants produce 6- to 7-ounce orange-red fruits 78 days after transplanting. When unblemished fruits are gathered before the first frost, they can last in winter storage for up to 3 months. (Flip to Chapter 19 for more on storing fruits and vegetables during the winter months.)

‘Striped German': This German heirloom indeterminate variety produces 16- to 32-ounce fruits with beautiful yellow-orange skin and red marbled flesh 78 days after transplanting.

Sweetening the pot with cherry, grape, and pear tomatoes

Cherry, grape, and pear tomatoes sound like fruits, and they may as well be for their sweet, melt-in-your-mouth flavor. Nothing is more satisfying to me than going into the garden and munching on handfuls of cherry tomatoes. Rarely do these babies even make it to the kitchen.

The latest newcomer on the small tomato scene is the grape tomato. Originally from Thailand, these tomatoes have a grape shape and are smaller than most cherry tomatoes. However, grape tomatoes have a thicker skin and are less juicy, which means they squirt less when you munch down on them. Because they're easier to eat, they're often found in place of cherry tomatoes in salad bars and restaurants.

Pear tomato varieties have been around for years. These red- or yellow-colored fruits look like small pears and are flavorful, but they generally aren't as sweet as cherry tomatoes.

Cherry, grape, and pear tomatoes can be very productive, so often, only one or two plants are enough to keep your family happy all season. If you're growing dwarf, patio-type tomatoes, they do best in containers. (See Chapter 18 for more on growing vegetables in containers.) Cherry, grape, and pear tomato fruits do tend to crack more easily than larger-sized tomatoes, so make sure that they have plenty of water and mulch (see Chapter 15 for watering and mulching tips).

Here are some of my favorite small tomato varieties:

‘Black Cherry': These 2- to 3-ounce black-red skinned and fleshed fruits have a complex flavor. The heirloom indeterminate plants produce cherry-shaped fruits 65 days after transplanting.

‘Golden Sweet': This indeterminate hybrid grape tomato features 1-ounce golden yellow fruits with a mild, sweet flavor and no cracking. Fruits mature 60 days after transplanting.

‘Juliet': This 1-ounce red, indeterminate hybrid, AAS-winning grape tomato is crack and disease resistant. It matures 60 days after transplanting.

‘Patio': This hybrid, dwarf plant produces grape-sized red fruits all at once about 70 days after transplanting.

‘Sun Gold': This hybrid indeterminate plant produces fruity tasting 1- to 2-inch-diameter orange-colored cherry tomato fruits 57 days after transplanting.

‘Sweet Million': This prolific hybrid indeterminate, 1- to 2-inch-diameter, red-fruited cherry tomato variety has good disease and crack resistance and matures early at 60 days after transplanting.

‘Tiny Tim': These open-pollinated, dwarf, 18-inch-tall plants are great for containers. They produce 1-inch-diameter red cherry tomato fruits 60 days after transplanting.

‘Window Box Roma': This hybrid determinate plant produces 2-ounce, roma-type, cylindrical-shaped fruits 70 days after transplanting on 18-inch-tall plants. This variety is perfect for producing a container of sauce-making tomatoes.

‘Yellow Pear': This is an heirloom indeterminate that produces yellow, 2-inch-diameter pear-shaped fruits on huge plants about 78 days after transplanting. Kids love the shape of these tomatoes.

Studying some saucy tomatoes

Eating tomatoes fresh from the garden is pure joy. However, you may want to preserve some of that fresh taste for cooking in the off-season like my mama used to do. If making tomato sauce, paste, salsa, and juice is for you, the following paste tomato varieties are bred to order. Even though any tomato variety can be processed, these pear- or plum-shaped types are meatier and thicker-walled and usually have less juice, so they're perfect for cooking. Many of these varieties are now bred to be good for fresh eating in salads and on sandwiches as well:

‘Amish Paste': These large, teardrop shaped red fruits are produced on indeterminate heirloom plants 85 days after transplanting. The fruits are meaty and flavorful, so they're super for making pastes.

‘Golden Mama': This 4- to 5-ounce, golden-yellow sauce tomato is produced 68 days after transplanting. These productive plants are indeterminate hybrids. The yellow sauce you can make from this beauty is appealing to the eye and has a sweet flavor.

‘Roma': This is one of the most popular processing tomatoes around. This open-pollinated determinate produces 3-ounce, plum-shaped fruits on compact vines 78 days after transplanting.

‘Super Marzano': A hybrid version of another popular paste tomato, this hybrid indeterminate has 4- to 5-ounce pear-shaped fruits that are more disease resistant and productive than their heirloom cousins. The fruits mature 70 days after transplanting.

‘Viva Italia': This sauce tomato is as good fresh as it is processed. It's a determinate hybrid that produces pear-shaped, 3- to 4-ounce fruits with great disease resistance 80 days after transplanting.

Elongated plum- or pear-shaped tomatoes tend to be more susceptible to blossom-end rot (see "Weather-related problems," later in this chapter, for more on this condition). To prevent blossom-end rot, keep the plants well watered, and mulch with a 4- to 6-inch-deep layer of hay or straw to keep the moisture levels constant. Pick off and throw away any affected fruits, and the new ones that develop should be fine.

Introducing the tomato's relatives

Just like in any family, tomatoes have some odd relatives. Following are descriptions of three of the most commonly known tomato relatives. They're all grown similar to tomatoes, but the flavors are much different. Try one of these varieties:

‘Husk Cherry' (Physalis peruviana; also known as ‘Strawberry Tomato' or ‘Cape Gooseberry'): These sprawling plants produce tons of small, papery husks similar to Chinese lanterns. Inside each husk is a cherry tomato-sized fruit that matures to yellow or gold. The flavor is like a sweet wild berry. Kids love these fruits. And because they self-sow readily, once you plant them in the garden, you'll have them forever. They mature 75 days after transplant.

‘Tomatillo' (Physalis ixocarpa): The standard ingredient in salsa, these tomato relatives produce papery husks like the ‘Husk Cherry,' but the fruits inside are ping-pong-ball size and tart rather than sweet. Varieties come in yellow and purple fruit colors. Fruits mature 65 days after transplant.

‘Tree Tomato' (Cyphomandra betacea-amarillo): Although technically in the tomato family, this tropical plant is as unfamiliar as the uncle you rarely see. It's a small perennial tree native to the Peruvian Andes that produces tons of hen's-egg-sized fruits that range from yellow to red when mature. The flavor isn't like a tomato but more like a tropical fruit.

‘Tree Tomato' plants need 18 months of warm weather to mature a crop, so unless you have a greenhouse, growing this variety is limited to gardeners who live in zone 10 areas. (Flip to the appendix to find out more about zones.)

Growing Tomatoes with Ease

After you decide on and purchase your tomato varieties, it's time to get them growing. In this section, I explain how to start your tomato plants; plant, fertilize, and maintain them; handle insects, diseases, and weather-related issues; and harvest them for your enjoyment.

Jump-starting tomatoes

Tomatoes require such a long season to mature that they're best bought as transplants through the mail or from local garden centers. You also can start them from seed indoors 4 to 6 weeks before your last frost date (I cover starting seeds indoors in Chapter 13; see the appendix for average frost dates in your area). Either way, you simply want to have a stocky, 6- to 10-inch tall, dark-green-leafed, flowerless transplant ready to go into the garden after all danger of frost has passed.

For gardeners in subtropical areas, such as southern Florida, you can plant two crops of tomatoes: one in the spring and another in the fall. Start seedlings indoors in January and February for planting outside in March and harvesting in May and June. For a fall harvest, start your seeds in July, or buy transplants for a late August or September planting. By late fall or winter, you'll be enjoying ripe tomato fruits while colder areas are eating snow.

Tomatoes love to be patted. If you're starting your tomatoes from seed at home, keep the plants short and stocky by brushing your hands over the tops of the seedlings ten strokes daily starting when they're 2 ½ inches tall. Research has shown that this brushing strengthens the stem and causes the seedling to stay short and squat, suffering less transplant shock when planted in your garden.

Tomatoes (and their roots in particular) love heat. To give tomatoes a jump-start, preheat the garden soil by covering it with dark plastic mulch. Lay the plastic sheet over the garden bed, pull it tight, cover the edges with soil, and let the plastic heat the soil for 2 weeks before transplanting. While you're waiting for the soil to heat up, harden off your transplants (in other words, gradually make them accustomed to the outdoor growing environment) with the guidelines in Chapter 13.

Planting, trellising, and pruning

Tomatoes are one of the most forgiving vegetables to grow. But to get the best crop, you need to plant properly, keep the fruits off the ground by trellising, and even prune the most vigorous bushes to keep them inbounds. I discuss some simple guidelines in the following sections.

Planting

Here are the basic steps for planting tomato plants:

1. Dig a hole twice the diameter and depth of the tomato root ball.

2. Place a small handful of all-purpose organic fertilizer or compost into the hole.

3. Plant the tomato transplant up to its first set of leaves.

Tomatoes have a unique ability to form roots all along their stems. So even if you have a tall, leggy, lanky seedling, just bury the stem either vertically or horizontally in the ground, leaving at least two sets of leaves poking out (see Figure 4-2).

If you're using plastic mulch, cut (or burn with a propane torch) a 6-inch- diameter hole in the plastic, and plant your tomato transplant directly through the plastic mulch using the same technique that I walk you through earlier.

Research has shown that red plastic mulch increases tomato yields by 20 percent. How? The red mulch reflects specific light wavelengths back into the tomato plant stimulating it to produce more fruit.

Trellising

As the weather warms, tomatoes grow quickly. So soon after you transplant, you have to decide which trellising method you'll use to keep your tomatoes off the ground. All but the dwarf and dwarf-indeterminate varieties need to be staked, caged, wired, or generally held off the ground to minimize the amount of rot and pest damage that the plants suffer. Figure 4-3 shows two basic trellising methods, which work well with tomatoes (see Chapter 15 for details):

Staking: To stake your tomato plant, you simply drive a wooden or metal stake into the ground right next to the tomato transplant when you first plant it. Fasten the main trunk of the tomato to the stake with flexible rubber or plastic ties, and then continue adding ties as the plant grows. Staking is often combined with pruning to produce fewer, but larger fruits.

Caging: To cage your tomato plant, buy a large, three-ringed metal cage and insert it into the soil around your tomato transplant when you plant. Keep any errant branches inside the cage by gently reorienting them. This method requires less work than staking, and unless pruned, caged plants produce more but smaller fruits.

Pruning

In addition to staking, another way to keep vigorous plants (especially indeterminates, which continue to grow all season) in bounds is to prune them. Removing extra side branches called suckers (see Figure 4-4) helps direct more energy to fruit production and less to leaf and stem production. When the suckers are 3 to 4 inches long, remove them from the plant by pinching them back to the main stem with your fingers or a pair of scissors.

Pruning suckers reduces the overall yield of your tomato plant, but the fruits you do get will be larger and will ripen slightly earlier than if you didn't prune them.

Fertilizing and maintaining your plants

Tomatoes are generally heavy-feeding plants. They like a soil rich in organic matter and compost, but they also respond well to side-dressing with fertilizers during the growing season. Maintaining proper moisture and mulching also are crucial for producing the best tomatoes possible. I explain everything you need to know in the following sections.

Side-dressing

Side-dressing is adding a small amount of fertilizer around or "on the side" of plants after they're growing. Side-dress with a complete organic fertilizer, such as 5-5-5, by sprinkling a small handful of the fertilizer around each plant. Apply the first side-dressing when the tomatoes are golf-ball sized, and then apply another side-dressing every 3 weeks after that. Scratch the granular fertilizer into the top few inches of soil. (Refer to Chapter 15 for more on fertilizers.)

Use fertilizers with lower rates of nitrogen; higher rates cause tomato plants to sport lots of dark green leaves and produce few tomatoes. Also, try not to get any fertilizer on the foliage; it can burn the leaves.

If you prefer to spray your plants, treat your tomatoes to a foliar feeding by mixing the fertilizer with water and then spraying it on the plant foliage; this is a quick way to get nutrients to your tomato plants. Using fish emulsion or seaweed mix, dissolve the fertilizers according to the recommendations on the bottle and spray the plants every 3 weeks. Plants can take up nutrients faster through their leaves than through their roots, but the effects don't last as long. Some research suggests that spraying plants with a seaweed mixture can also help reduce leaf diseases.

Tomatoes also like Epsom salts. Research has shown that 1 tablespoon of Epsom salts dissolved in 1 gallon of water and sprayed on the transplants after planting and a month later makes for greener and more productive tomatoes.

Watering and mulching

Watering is critical if you want your tomatoes to produce the best quality fruits. In general, tomatoes need 1 inch of water a week, but they may need more in areas with hot, dry, windy summers. Chapter 15 discusses watering strategies in detail.

One of the best things you can do to conserve moisture is to mulch around your tomato plants. Plastic mulch conserves some moisture but is best used in conjunction with soaker hoses or the ditch watering method (see Chapter 15 for details). The best water-conservation mulch is a 4- to 6-inch layer of hay or straw. The mulch is thick enough to prevent weeds from germinating and stop soils from drying out.

Hay and straw mulches keep soil cool, but tomatoes love heat. So, if you're in an area that has cool summers, wait until the soil has warmed and the plants are thriving before mulching with these materials.

Mulching and watering evenly also prevents many fruit problems, such as blossom-end rot and fruit cracking. See the section "Weather-related problems," later in this chapter, for details on these conditions.

Eliminating pests and other problems

Tomatoes grow so vigorously that they often outgrow any problems and still give you a harvest. But to get the most out of your plants, look out for the troubles in the following sections, which are caused by insects, diseases, or weather. (For a general description of and a plan of action against common insects and diseases, see Chapter 17.)

Spray with pesticides only as a last resort; many plants can withstand a small infestation of bugs or a few diseased leaves.

Insects to watch for

Here are a few insects that are a particular problem with tomatoes:

Tomato hornworm: These huge, green caterpillars, which sometimes grow to 4 inches long, look like the monster that ate Tokyo (see Figure 4-5). They eat leaves and fruits of tomatoes, and I swear that if you're quiet enough, you can hear them chewing. A few hungry hornworms can devastate a tomato plant quickly.

The simplest control is to handpick the caterpillars off the plants and wrestle them into a can of soapy water to drown. Early morning is the best time to remove these pests from plants — like many people, they're still sluggish at this time of day.

Tomato fruitworm: This green, 1-inch-long caterpillar with white or yellow stripes feeds on foliage and fruits. They can be handpicked from plants as with the hornworm; however, for a severe infestation, you also can spray plants with Bt.

Stink bug: A problem mostly in warmer areas, these 1/2-inch-long gray or green shield-shaped insects primarily feed on fruits, causing hard, white or yellow spots on the tomato skin. To control stink bugs, keep your garden weed-free — the pests hide in weeds around the garden — and spray plants with pyrethrin.

Chapter 17 discusses pests and ways to rid your garden of them, such as using Bt and pyrethrin, in more detail. Flip there to read more.

Got a disease?

Leaf diseases, such as the ones in the following list, can devastate tomatoes:

Blights and leaf spots: The devastation starts with the lower leaves getting brown spots, turning yellow, and eventually dying. The symptoms of leaf spot look similar to the symptoms of late and early blight. The disease slowly spreads up the plant, eventually defoliating the whole plant. These fungal diseases are particularly active during warm, wet weather. To control blight and leaf spots:

• Clean up and destroy all diseased foliage in the fall.

• Rotate crops, as described in Chapter 16.

• Mulch the plants with plastic, hay, or straw after planting to prevent water from splashing the spores from the ground onto the leaves.

• Before the condition gets severe, spray with an organic fungicide, such as copper or Bacillus subtilis.

Verticillium and fusarium wilt: These soil-borne fungal diseases cause yellowing, wilting, and early death of tomato plants. Once infected, the plants will likely die and should be removed. The best prevention is to rotate your plantings and plant wilt-resistant plants (indicated by the letters V and F after the variety name).

Luckily, many varieties of tomatoes now are resistant to some of these diseases. Use the guidelines in Chapter 17 to reduce the amount of disease in your garden.

Weather-related problems

Not all problems with tomatoes are related to insects or diseases. Too much or too little water, too much fertilizer, cold temperatures, and varietal differences can all contribute to deformed fruits. Here are a few of the more common problems and some solutions:

Blossom drop: Your tomatoes are flowering beautifully, but the blossoms all seem to drop without forming any fruit. This condition, called blossom drop, is caused by air temperatures above 90 degrees Fahrenheit or below 55 degrees Fahrenheit. At these temperatures, most tomato flowers will not set fruits. The solution is to grow varieties adapted to the heat (such as ‘Solar Fire') or cold (such as ‘Cold Set'). Or you can protect the plants during flowering with floating row covers.

Blossom-end rot: With this condition, the bottom, or blossom end, of tomatoes turns brown and rots. Blossom-end rot is caused by fluctuating moisture conditions in the soil, so the best cure is to mulch the plants well, plant them in well-drained soil, and keep them evenly watered.

Fruit cracking: Many types of fruit cracking affect tomatoes, but all involve fluctuating moisture conditions and exposure to cold temperatures early in the season. To avoid this problem, plant varieties that are less likely to crack (such as ‘Big Beef'), reduce nitrogen fertilization, mulch the plants to keep the soil moisture even, and protect flowering plants from cold nights with row covers (see Chapter 21).

Sunscald: You'll know that your tomatoes have sunscald if the top surfaces of the fruit skins have lightly colored patches. These patches, which are caused by direct exposure to the sun, eventually rot. To avoid sunscald, grow indeterminate varieties that have lots of foliage to shade the fruits (such as ‘Better Boy'), avoid pruning the leaves, and provide afternoon shade with shade cloths. Or you can grow the plants in cages instead of staking them.

Harvesting tomatoes

Harvest tomatoes when they're fully colored and still firm to the touch. Tomatoes don't need direct sun to ripen, just warm temperatures. Tomatoes will continue to ripen indoors if they're picked too early, so it's better to err on the early side when harvesting. As long as they show some color when picked, they'll ripen indoors with that vine-ripened flavor.

If you want to push the harvest along, you can prune off some new branches and tiny fruits to redirect the plant's energy to the larger, maturing fruits. You also can root-prune the plant, cutting 6 inches into the soil in a circle one foot away from the stem of the plant. Root-pruning severs some of the roots, shocking the plant and forcing it to ripen its fruits faster. It will, however, stop the production of new fruits, so this technique is best used at the end of the season.

If you live in an area with bright sunshine, don't prune off tomato foliage. Removing too much foliage results in sunscald, a condition in which the tomato skin literally gets sunburned. Sunscald itself doesn't ruin the tomato crop, but it opens the door for other rot organisms to attack the fruit. (See the previous section for more details.)