Tips for Great Tomatoes

Start with dark green, stout transplants equally high and wide, preferably about 4 inches in each direction.

Plan to grow a mix of heirlooms and hybrids for a little insurance: Heirlooms are beautiful, delicious and a critical part of our genetic heritage, but sometimes they lack the disease-resistance (often labeled VFN) of hybrids. I like to mix it up.
Remember that even with hybrids rated as having VFN resistance, the word "resistance" is the operative phrase. It means less-susceptible, not immune. There is no substitute for good cultural practices, whatever variety you begin with.

Identify a full-sun spot outdoors where your tomatoes will grow. Now pick another such spot, and preferably a third. You will need more than one area for tomatoes, since crop rotation is one of the key lines of defense against tomato various diseases that can overwinter in the soil. No potatoes, eggplants, peppers or tomatillos, can go there in the off years, either.)

While your transplants shape up, prepare the soil: Start with a soil test, or at least a simple pH test. Tomatoes like a pH of about 6.5 (6.0-6.5 or so is fine). In acidic soils like mine, the addition of lime is recommended, at the rate of 5-10 pounds per 100 square feet worked into the top 6 or so inches.

High-quality finished compost is the best amendment you can add to support great tomatoes. Work in a 2-to-3-inch layer each year.An all-natural organic fertilizer that's balanced or has a slightly higher middle number (not one high in Nitrogen) can also be incorporated according to package directions.

Decide how you will support the plants, to keep them up off the ground, for best health.Staked plants will ripen faster crops of generally larger fruit. Stakes must be at least 1 inch thick and 6 feet high, inserted a foot into the ground. Remember: Staked plants require a commitment to ongoing pruning, keeping the plant to one or two main stems of vine-like, not bush, habit. All small suckers that develop in the crotches between the leaves and the main stem must be removed. I do not have the energy for this, so I cage my plants.

Caged plants are easier to care for, and in the longterm may produce heavier yields (because they have more branches and stems). Another advantage of cages: You can use them as mini-greenhouses should late or early frosts come, by having clamps and reusable pieces of clear, heavy plastic cut to wrap each cage. Some expert growers always put the plastic on in the first weeks to reduce negative effects of wind on young plants.

After all danger of frost is past, it's planting time. Hurrying doesn't help, and it can hurt.Plant deep, at least to the level of the original seed leaves, or even to the topmost couple of pairs of leaves. Water in well, applying first of two doses of liquid feed; see below under "Douse each plant's root zone," for details.
Space plants at least 2 feet apart in each direction; 3 or more would be much better, as air circulation is another disease-preventive tactic. Caged plants need wider spacing than staked, and indeterminate varieties more than some determinate; plan accordingly.

A layer of clean straw or some other organic mulch will further reduce splashing of spores and other woes up from the soil onto the plants. Snip off any flowerbuds that set until the plant is settled in and growing strong, after it reaches perhaps a foot tall or so.

Tomatoes will rely on you to team up with the heavens and provide consistent moisture, consistent being key here. Ideal is the equivalent of an inch of water throughout the entire growing area; half again as much in the heat of summer. Remember: an inch of rain (which is what you are simulating) is a lot of rain, and takes a long time to apply. Use soaker hoses or a drip system, not the end of a hose. If you must use a sprinkler, use it in the morning, so that foliage can dry by day, and don't work in the garden while the foliage is damp.

Douse each plant's root zone with a liquid feed twice during the growing season. Some growers swear by doing this at transplant time and again when the first flowers appear; others say transplant and first fruit. Just remember to do it while they are in their run-up to adulthood and you will be fine. Powdered seaweed fertilizer or fish emulsion diluted in water according to label directions are two non-chemical possibilities.
Be vigilant about watching for tomato hornworms and their telltale droppings or first signs of their chewing damage. The droppings are easier to see than the green caterpillars, who normally start their eating at the tops of plants. Pick them off and destroy them.

Sometimes, despite all this love, tomatoes fail to set fruit. Assuming you did not give the plant too much Nitrogen, it may be weather-related: Nighttime temperatures that remain above 70 or temperatures below 50ish interfere with pollination. Fruit set can also be hampered by over-feeding with Nitrogen or by irregular watering.

And one more thing: Please, don't grow your tomatoes upside-down, as is the fashion started by at least one recent gimmick product. Yes, they'll grow if you follow the instructions, but why would you bother, why spend the money? The tomato experts at Rutgers agree with me on this one, by the way. I think there's enough upside-down in the world without us adding to the dizzying picture, no?
Growing tomatoes has its challenges.

We gardeners can provide the basics of fertile soil, full sun, mulch, staking or caging, and also try to offset the heavens to create an even supply of soil moisture. We can also grow resistant varieties, and plant them really deep for maximum rooting.
But what's perhaps the most valuable tactic against tomato troubles—rotating your crop on a three-year cycle—isn't so easy if you don't have three big-enough full-sun spots to alternate among. And rotation means no potatoes, no peppers.

Below is the barest minimum of explanation to why some tomato problems occur, followed by some links I've collected to expert diagnostic sites that may help you get even more specific if the individual links within the sections don't help.

ROT ON THE BOTTOM: The bottom of a tomato fruit is the blossom end, where the blossom used to be before the fruit expanded. Blossom-end rot can appear as leathery and sunken, or be watery-looking; the end is discolored, and dark. The cause: not enough calcium, caused by water stress. Some gardeners work lime or calcium into the beds as a preventive measure.

GREEN ON THE TOP: On the top or stem end, problems such as "greenback" can occur when areas around the stem remain hard and green, unripened. Too much sunshine can sometimes be the culprit there.

SEEING SPOTS? Various fungal diseases, cankers, viruses and bacterial conditions can show up as spots on tomato skin, whether red or green. If your tomatoes get anthracnose (sunken round spots that then go dark in the middle, sort of a bull's-eye effect), alternaria canker (also known as blight, with numerous sunken gray-brown marks on fruit, both green and red, and lesions on plants, too), or black mold and ghost spot (watery spots with dark centers), crop rotation might have helped prevent it, and is a must next year.

As mentioned, a three-year cycle is ideal; two is good; skipping a year helps with some conditions and not others, but is better then no rotation.
A barrier of clean mulch applied at planting time can reduce some spores that splash up from the soil onto plants. Heirloom tomato expert Amy Goldman is using a new (reusable) material, ground cloth, the stuff of greenhouse floors and nursery pathways, and I have to say it's looking pretty attractive to me.

TOMATO FOLIAGE: can also experience all manner of spotting, and many such afflictions are symptoms of the same cankers, blights, fungi and viruses above. Sometimes leaves start to fall off after yellowing, moving up the plant, other times it's top-down. Bacterial wilt is a top-down deal; fusarium and verticillium begin at the bottom of the plant.

WHEN NO FRUIT SETS:Sometimes tomatoes fail to set fruit, or set it and then drop it when it's barely the size of a small bead. Hot, dry conditions at blossom time prevents proper pollination and causes buds or tiny fruit to drop. If it's early enough, hopefully a next round of flowers appears during more favorable weather. I know some gardeners who hose down their plants if the weather is inhospitable, hoping to encourage fruit set.

CRACKS: often develop when soil moisture is uneven, and lots of moisture becomes available suddenly after not enough. Fruit swells faster than the skin can expand. Too much Nitrogen can bring on cracking, as can some fungal diseases and even merely plant genetics (large-fruited beefsteak types are said to be more susceptible).

FAVORITE DIAGNOSTIC SITES: The University of Maryland, as well as Texas A&M and also Cornell University, each has a great, photo-driven diagnostic tool that you will want to bookmark. And Maryland's chart of the disease resistance of various tomatoes was one of the most extensive I could find. Resistant or not, though, each of us has our own special favorites.