Gardening Basics: Tomatoes

Choosing Tomato Varieties
By: National Gardening editors
So many tomatoes, so little space!
Healthy, vigorous tomato vines can produce a lot of fruit. If you're new to gardening, try growing just a few tomato plants at first — perhaps two or three plants of two to three different varieties. But of the thousands available, from cherished heirloom types to the hottest new hybrids, how do you narrow your choices?

Criteria for Choosing Varieties

When do fruit ripen? Since varieties mature at different times, you can stretch your harvest over many weeks. If you're buying seeds to start your own plants, read catalog descriptions carefully to discover "days to maturity." This indicates approximately how soon you can expect ripe fruit once you've transplanting seedlings to the garden. Plants sold at garden centers are often labeled "early," "midseason," or "late" to indicate when the variety should start ripening.

Determinate vs. Indeterminate. Another consideration in choosing tomato varieties is whether the vines are determinate or indeterminate. Determinate plants stop growing once the flower buds emerge. Because of their more restrained size, many determinate varieties need no staking or caging, but providing support can improve the quality of the fruit. All the fruit ripens within a relatively short period of time - usually about a week to 10 days. This can be a boon if you're canning, but for the gardener who prefers to have a fewer number of tomatoes over a longer period of time, indeterminate varieties are better. The vines continue to grow and set fruit throughout the season, and won't quit until the weather turns too hot or too cold to sustain fruiting and growth, or kills plants outright.

For gardeners with little space to spare, or only a deck or balcony to grow on, patio and bush varieties are a good option. They're more compact than determinates, yet produce fruit throughout the season like indeterminate types. They are bred to succeed in small spaces.

What to do with the fruit? When selecting a tomato variety, keep in mind what you plan to do with the fruits. There are varieties suited for just about every purpose — eating fresh, making tomato paste, canning, drying — even for cultivating into a county fair prizewinner.

Seeds or Transplants. The easiest way to get your tomato patch started is to purchase young plants, also called transplants or starts. You can pick up plants at garden centers or order them through catalogs or the Internet. For years, gardeners who bought plants had a very narrow field of variety choices, but thanks to an expanding mailorder trade, the options are greater than ever.

That said, starting your own seed gives you an almost endless list of varieties to choose from, allowing you to get just the type that will suit your growing conditions and tastes. Starting seeds gives you a chance to start "gardening" earlier in the season, and nurturing plants from seed to harvest is a great experience. Plant seeds six to eight weeks before the last frost date for your region, and place them under flourescent light. (For seedstarting details go to Starting Tomatoes from Seed. Call cooperative extension Master Gardeners or your local weather service to find out your last spring frost date.

Disease resistance. By planting tomato varieties with built-in resistance to diseases, you can have a bit more control over your garden's success.

For instance, many tomato varieties are resistant to soil-borne diseases such as verticillium and fusarium wilts and nematodes. Most seed catalogs indicate resistance to these diseases by putting F (fusarium), V (verticillium), N (nematodes) after the variety name. You'll also see varieties with resistance to viruses such as tomato mosaic virus (T), and to alternaria (A), the fungus that causes early blight.

Talk to the Master Gardeners office or to neighboring home gardeners. They can tell you if certain tomato diseases are common in your area.

Experiment! If you're not counting on your garden as your only food source, you can certainly afford to risk planting the varieties that appeal to you — perhaps an heirloom that, though not resistant to disease, is reportedly produces the most delicious tomatoes in the world. Experimentation is part of the joy of gardening, and part of your harvest is what you learn along the way.


Photo by Suzanne DeJohn/National Gardening Association
Transplanting Tomatoes
By: National Gardening editors
Transplanting is a major step. If you do it carefully, you can look forward to a crop that will be healthy and prolific. Rushing your plants into the ground before they're properly hardened off, or roughing up the tomatoes' roots when you're handling them can set the crop back. Read Hardening Off Transplants for more information on acclimating your seedlings to the great outdoors.

If you talk to other gardeners, you'll quickly get the notion there are as many methods, tips and tricks to the art of transplanting as there are ways of baking a cake. Read more about the relative benefits of trench and vertical planting before deciding which is right for you. Below are the basics upon which variations are based.

*Plant your tomato patch on a sunny site. These heat-loving vines need at least 6 hours of direct sun to produce a crop, and the cooler and shorter your growing season, the more sun they'll need.

*It's ideal to transplant on a cloudy, calm day to reduce stress from sun and wind, but if your plants have been exposed to these conditions during hardening off they should suffer little or no setback. Planting in late afternoon or evening allows plants all night to settle in before a full day of bright sun.

*An hour before transplanting, soak roots with fish emulsion or seaweed fertilizer diluted as per label directions. Moist rootballs are easier to slip out of pots, and the fertilizer provides nutrients to support plant health during the transition.

*Before taking plants from their pots, prepare the soil, add compost or fertilizer to trenches or planting holes, a full watering can or hose, and material for cutworm collars (see below) at the ready.

Note: If you're using a water soluble commercial fertilizer, cover it with an inch or two of soil before setting the plants in place. If the fertilizer, which is made of soluble salts, comes in contact with roots, it can dehydrate and damage them. Read the fertlizer label carefully and use it only as directed - more is not better!

*Protect against cutworms. These ground-level pests can chew completely through thin tomato stems. Wrap a newspaper or paperboard collar around the "trunk" of each plant so that they span from an inch or two above the soil surface to an inch or two below. These biodegradable barriers last long enough for the stems to grow to the point where they can resist hungry cutworm.

*Working quickly, cup the roots in one hand as you remove the transplant from its container, and tuck it into its home in the garden. A smooth and speedy transition from pot to soil means less shock to the plant.

*Water well to settle soil around the roots, and don't let the soil dry out during this crucial transition time. A layer of mulch - straw, grass clippings, compost, and the like - helps prevent moisture from evaporating from the soil.
Pruning Tomatoes
By: National Gardening editors
Pruning means pinching off the shoots or "suckers" that sprout from the stem in the crotch right above a leaf branch. If you let a sucker grow, it simply becomes another big stem with its own blossoms, fruits and suckers! With staked or trellised tomatoes, pinch off the suckers and just keep the energy of the plant directed at one (sometimes two to three) main stems.

If you want additional stems to develop besides the main stem, allow the suckers closest to the bottom of the plant to grow. These will have more flower blossoms and are easier to train to the outside of the plant than suckers that sprout higher up.

Tomato plants really grow fast when the weather warms up, and new suckers form all the time, so you should go on "sucker patrol" at least twice a week during the heavy growing season.

If you live in a very hot, sunny area, you can let some of the suckers put out a couple of leaves and then pinch out the tips to stop their growth. The sucker provides a little more foliage to help the plant manufacture food and also to help shade tomatoes from the sun.

Pruning Unstaked Plants

Unstaked plants can also be pruned, although it's not as necessary as it is for staked or trellised plants. Pruning improves ventilation, which can help to prevent disease problems. Pruning branches late in the season opens the plant up to more sunlight. Then on cooler days the plants are a little warmer, which is good for ripening tomatoes.

If you're growing determinate varieties of tomatoes, go easy on any pruning. Because these plants are smaller and don't continue to set new fruits throughout the season, heavy pruning may reduce your yield drastically. Also, be careful not to overprune in hot parts of the country. Tomato fruits need protection from the bright sun or they may develop sunscald. Tomatoes ripen better if they're shaded some by foliage.

Pruning Tops of Plants

You can pinch off the tip of the main stem above the top blossom of indeterminate tomato varieties to keep a flourishing plant from getting any higher. This type of pruning can be helpful when a plant is outgrowing its support, or toward the end of the growing season when a taller plant won't help much in terms of increased production. At that point, you'd prefer to see the plant put its energy into ripening the tomatoes already on the vine.

Pruning Roots

Root pruning is a special trick you can use to speed up the ripening of early tomatoes. It simply involves cutting some of the roots of a plant when it has three or four clusters of tomatoes on it. By cutting the roots, you put quite a bit of stress on the plant, which causes it to mature more quickly. It's as if the plant were worried that it might not have time to complete its life cycle, so it rushes to mature some fruit and seed. The plant won't die if you root-prune it correctly; the growth process is simply interrupted. But after a little rest, the plant is ready to start producing again.

To root-prune trench-planted tomatoes, take a long kitchen knife and make a cut down along just one side of the buried main stem, 1 to 2 inches away from it, going down 8 to 10 inches. If the tomatoes are planted vertically, cut halfway around the plant, 1 or 2 inches from the stem and 8 to 10 inches deep. If a knife doesn't work well for you, try a spade or a shovel.
Ripening and Harvesting Tomatoes
By: National Gardening editors
One of the great joys of gardening is reaching for the first red-ripe tomato on the vine and biting into it. There's a flavor, juiciness and pleasure you'll never find in a supermarket tomato. Because tomatoes ripen from the inside out, when the outer skin is firm and red, you know you've got a beautiful ripe one.

Getting Them to Turn Red

The red color of tomatoes won't form when temperatures are above 86oF. So, if you live where the summers get quite hot, leaving tomatoes on the vine may give them a yellowish orange look. It's probably better to pick them in the pink stage and let them ripen indoors in cooler temperatures.

Tomatoes need warmth, not light, to ripen, so there's no need to put them on a sunny windowsill. Place them out of direct sunlight - even in a dark cupboard - where the temperature is 65 to 70oF.

Frost-Time Harvest

Tomatoes succumb to frost, but don't panic when the weatherman predicts the first one and your tomato vines are still loaded with green fruit. If it's going to be a light frost, you can protect the plants overnight by covering them with old sheets, plastic, burlap bags or big boxes. It's usually worth the effort because the second frost is often two or three weeks after the first one.

If a heavy freeze is on its way, go out and pick all the tomatoes. Green tomatoes that have reached about 3/4 of their full size and show some color will eventually ripen, and smaller, immature green ones can be pickled or cooked green.

Some people like to pull up the whole tomato plant and hang it upside down in a dark basement room and let the tomatoes ripen gradually. If you try this system, check them regularly to prevent very ripe fruits from falling onto the floor - splaat!

The Shelf Method

Another method is to put unripe tomatoes on a shelf and cover them with sheets of newspaper. Every few days check under the newspaper and remove ripe fruits or any that have begun to rot. The newspaper covering helps trap a natural ethylene gas that tomatoes give off, which hastens ripening. Some people wrap each tomato individually, but this causes a lot of work when you want to check for ripe tomatoes: You have to open each one! You can also place tomatoes in a paper bag with an apple or banana. The fruits give off ethylene gas, which helps to speed the tomatoes' ripening process.

Fall Tomatoes

In parts of the southern and southwestern states you can grow an abundant crop of fall tomatoes. However, finding young tomato plants to buy in the middle of summer may be hard.

An easy way to solve this problem is to cut small suckers from spring-planted tomatoes and let them grow to full-sized plants. Instead of pinching out most of the suckers on your tomato plants, allow some to grow four or five inches. Then in mid- or late summer, cut the suckers from the plant, remove the lowest set of leaves and place the suckers in a jar of water or moistened sand or vermiculite. This will start the rooting process. Once roots begin to form, plant them in pots or directly in the garden. Firm the soil around the suckers and water them heavily for two or three days.

These plants will do just as well as any you could raise from seed or buy at a garden store. Just be sure they don't have any insect or disease problems or you'll be fighting them all fall. The plants will give you a nice fall crop of tomatoes, too.