What you need to know about tomatoes

Several have sheepishly asked what the terms "determinate" or "indeterminate" mean and why are they on the plant label. The answer is they describe the fruiting and growing habits of the particular plant. It turns out these are really important terms to know when growing a tomato, so the answer is worth repeating.

The determinate tomato plant grows sort of like a tree. It gets to a height, fruits, and that is it for a while. Usually about six weeks, when it might flower again. The indeterminate tomatoes grow more like vines, the growing tip or tips keep getting farther and farther away from the soil. They also tend to fruit as they grow instead of all at once, more of a continuous affair (perfect for the wandering greenhouse worker in need of a tomato fix).

Next, some wanted to know about their plants' first flowers. Should they pick the first batch off to increase fruit? Ah, good questions because of the misconceptions out there.

First of all, let me repeat what many find out too late: For most tomato varieties, you need night temperatures above 55 degrees in order for the flowers to "set" and then develop into fruit. This means a greenhouse is necessary in almost all instances here in Southcentral. It also means closing up the greenhouse in the early evening in order to conserve heat. Adding water barrels to hold heat and release it during the cooler evenings is a great idea. A heater may even be necessary, depending on the condition and location of your greenhouse.

Anyhow, once you get those flowers, should you pick them off? Why on Earth would you want to do that? If the plant needs to abort some flowers, which many do when they first appear, it will happen naturally. Picking off flowers means those you get won't turn into fruit for you. Don't do it.

It is not necessary to cover plants at night to get them to flower or fruit. The natural shift in daylight will take care of any need in the photoperiod department. What is necessary is for you to ensure the flowers you do get are pollinated -- and here is where many gardeners make a big mistake. They become so concerned about heat retention in order to get flowers to set that they don't open the greenhouse doors and allow insects to pollinate the flowers.

At a minimum, shake plants with flowers to get that pollen flying about. Better would be to go from flower to flower and back again with a small, artist paint brush and let your inner bee out. It doesn't take long, and it causes you to really look at your plants. Personally, I like the insects doing their thing, so the door gets propped open.

Someone wanted to know if she had to stake up tomato plants. In almost every instance, the answer is "yes." The exception is hanging plants -- that includes those "upside" contraption plants. And the appearance of flowers means it is time to stake or string up plants. Those fruits will weigh heavy on their stems and eventually the stalks and branches will suffer the weight as well.

There are lots of systems and lots of gadgets to help support your plants, from simple stakes and twists to special wire cages or string systems with plant clamps. Whatever you chose must fit your greenhouse and your plants' needs, but do support your plants, and do it now.

Next, white flies, the pest that, for many who buy tomatoes, won't go away. What do I recommend? Well, the good news is they really don't harm the plant. They are a horrible nuisance, however. One product that has worked for me is AzaMax, a neem oil product that I think is the line of first defense as it is safe and appears to be effective. Read the label for more information and directions for use.

Finally, I am getting questions about small, pale plants, very spindly, with a purplish tint to some of the leaves. All were nursery purchased. To me these are signs the plants are probably nitrogen deficient. During the first part of life, tomatoes need plenty of nitrogen to grow and flower. They get fed at the nursery and, unless they are organically grown, need help from you when they come home. If yours are showing these signs, chances are you didn't get them enough nitrogen. You still may be able to rescue them with some compost tea, alfalfa meal, blood meal, fish meal (local is best), soybean meal or organic tomato food, but do keep it organic. And it might be a good idea to rush to the nursery and see if they have a few better-sized plants left.

Once tomatoes do flower, incidentally, they don't need as much nitrogen as they do phosphorus, represented by the middle number on the label. Make it organic, of course.

Hear Jeff Lowenfel's "Garden Party" from 10 a.m. to noon on Saturday mornings on KBYR radio, AM 700. Call in with questions, 274-5297 or 1-866-610-5297.