The month of May is the transitional period between cool-weather plants and warm-weather types for Howard County gardeners. Our average, last frost date comes mid-May.

In the vegetable garden, efforts turn from broccoli and lettuce, already well on their way, to warmth lovers like tomatoes, peppers and squash.

Flower-wise, the pansies and calendulas will slowly give way to petunias and marigolds. Our mid-Atlantic position can, in a good year,give us the best of both seasons.

To many area gardeners, warm-weather gardening means only one vegetable -- tomatoes.

Tomatoes areby far the most popular item in home gardens with more than 93 percent of us, according to the National Gardening Association, raising them.

The promise of having fresh, vine-ripened summer tomatoes is the hook that pulls many of us into gardening in the first place.

Columbian Herbert Simmons comes close to mastering all four seasons, as far as vegetable gardening goes.

Tomatoes are just one of his fortes. Twenty years ago, a whim led him to give gardening a try, he says. He started reading Cooperative Extension Service publications -- a source he highly recommends -- and dug in.

He has been gardeningever since, enjoying it more every year, especially now that he is retired.

His meticulously kept garden, more than 2,000 square feet of it, is located at a community garden site.

The layout is complemented by sturdy fences, trellises and a raised, boxed bed especiallyprepared for root crops. It draws novices, as well as experienced gardeners, like a magnet. They seek him out for advice on everything from squash borers to tomato cages.

He modestly shares what he knows. His claim that he "plays it by ear" when it comes to garden problems may seem casual. But underneath lies a wealth of careful observations and a scientific approach.

Whether you grow an assortment of summer vegetables, or just tomatoes, the time to plan for a good tomatocrop is right now.

But don't feel it necessary to get out and plant right away. It seems as if garden centers and nurseries push for earlier sales of everything, including tomatoes, each year.

Plants purchased too early waste away on the window sill, awaiting suitable weather for planting outdoors.

Although Simmons gets an early start on gardening each spring-- the overwintered spinach and scallions and the thriving peas, broccoli and cabbage are proof of that -- he holds off planting any tomatoes until after May 5.

And then, much depends on the weather. Some gardeners swear it is a waste of time to put them in much before June 1.

Tomatoes need warm air and warm soil to grow; in some cases, cool weather may damage them, creating low fruit production even when warmer conditions arrive.

On the other hand, to say that tomatoes are heat-lovers is a bit misleading. Theirpreferred environment is 70- to 75-degree days and 60- to 65-degree nights. Days above 90 degrees with warm nights are detrimental to theplants, causing blossoms to drop and new fruit production to cease.

Besides proper timing, success with tomatoes rests on many factors, notes Simmons. Something as simple as plant selection can make a world of difference.

Although he has "fooled around" with many varieties, he now sticks with disease-resistant types. Choose only those varieties with VF after the names, he says. This means that they are resistant to verticillium and fusarium wilt, two of the most common diseases.

His favorites are "Better Boy" and "Supersonic."

"Better Boy" is labeled as an indeterminate variety -- that is, with care, it will keep producing fruit, growing up and out, until killed by frost.

Determinate varieties are smaller and produce fruit for a shorter period. "Supersonic" is a semideterminate type whose growth habitfalls somewhere in between.

Carefully prepared, well-drained soilthat has a high organic content is an invaluable asset, too.

Simmons prepares each planting hole with additions of peat, compost and composted horse manure. This not only provides nutrients, but good drainage and loose soil that makes weed-pulling easy.

The manure, he finds, works just as well, if not better, than chemical fertilizer, on tomatoes. He gives a second dose, in the form of a manure-and-watermix known as manure tea, to the plants as they start to bloom.

Applications of too much nitrogen -- the first number on the fertilizerbag -- he discovered, results in lots of leaves and few fruits.

He also adds plenty of ground limestone, not only at planting time, but throughout the growing season.

He works it into the soil around the plants, and even sprinkles it directly on the foliage. He creditsthe liming, along with regular watering, with saving his crop from blossom-end rot last summer.

While many gardeners around him lost most of their first tomatoes to the disease, Simmons saw none of it. Bugs don't like the lime either, he observed.

Another important ingredient to Simmons' success with tomatoes, especially indeterminate types, is the use of cages -- not the puny cone-shaped variety sold atgarden centers, but huge, cylinders of concrete-reinforcing wire.

He puts them in place at planting time to avoid any later disturbance to the plant's roots or stems.

Each cage is made from a 5-foot-wide roll of reinforcing fence. A 7 1/2-foot length is curled to create an almost 2 1/2-foot diameter cylinder, wired shut and stripped of the bottom rung so that the resulting wire stakes can protrude into the ground. He further anchors the cages with stakes.

Come September, he says, winds can topple the plant-filled cages that are not secure. This says something about how large his tomato plants get.

Many of us crave the taste of that first ripe tomato and will do our best to hurry the harvest.

The prestige of producing the first home-grown tomato in the neighborhood was more pronounced in the days when almost every yard sported a vegetable patch. But the tradition carries on in spite of our increasingly urbanized environment.

Garden centers are well aware of this preoccupation with early tomatoes.

There is a good market for the large potted tomato plants, already flowering and/or with small green fruit. They sell well, even at outrageous prices.

If you purchase one of these, make sure that the plant is not pot-bound, is a healthy green and has been properly hardened off.