Northwest Missouri Horticulture: Home Garden Tomatoes

In almost every survey, tomatoes always come out on top as the favorite vegetable of home gardeners. And why not? They’re easy to grow and even a single plant will produce lots of vine-ripe fruit that can’t be equaled.

The first factor to consider is what variety to grow. If you don’t start your plants from seeds, you will be limited to the varieties of plants that you can buy in local stores. Starting tomatoes from seed is easy, but they need to be started very early if you are going to have fruit before midsummer. For earlier fruit, buy good quality plants.

The choice of variety is somewhat subjective. Everyone has their favorites. I usually suggest that you try out different varieties, since you may find a new one that you really like. Grow your favorites, but try out a new variety or two each year as well. Also, some varieties are better adapted to an area than others, so by trying out different varieties, you will find out what does best for you.

Varieties will differ, however, in their ability to withstand diseases. This is especially true if you have soil-borne problems such as verticillium wilt, fusarium wilt, or nematodes. Look for a V, F, or N (or combination of those letters) next to the variety name. This indicates that the tomato variety is resistant to verticillium wilt, fusarium wilt, or nematodes. You may also see other letters, like T (tobacco mosaic virus resistance), A (alternaria stem canker resistance), or S (grey leaf spot resistance).

Another consideration in choosing a tomato variety is fruit set in hot weather. When the temperature climbs close to 100 degrees, tomatoes do not set fruit well. Some varieties have been bred for hot climates, and will set fruit better under high temperatures.

You can also choose between determinate and indeterminate varieties. Determinate varieties have more compact vines, usually between three and five feet in height. Indeterminate tomatoes are more "viney," and some vines may reach lengths of eight feet or more. These plants will obviously need some kind of support system, such as staking. There are also semi-determinate varieties, which have growth habits in between the determinate and indeterminate types.

You can also choose between color, size, and type. Tomato varieties have been developed for all kinds of traits and purposes: low-acid, processing, cherry types, sweeter types, hot weather, earliness, disease resistance, etc. There’s no perfect variety. Just choose what’s best suited to your purpose, needs and preference.

If you would like to grow tomatoes, but don’t have a garden spot, tomatoes can be grown in containers. I’ve seen them grown in five gallon buckets, for example. Container-grown tomatoes will have to be monitored more closely for water needs, and perhaps a little extra fertilizer. You can also move them around, if needed. If you choose to grow your tomatoes in containers, I would suggest a determinate variety. Also, be sure to use a potting soil, not garden soil, when using containers.

Tomatoes may be planted any time after the danger of frost is passed. But keep in mind that they are warm-weather plants, and don’t like the cold. They may need covering if cold temperatures are forecasted. Just remember to take the cover off after it warms up, so that they don’t cook.

In my next column, I’ll cover fertilizing tomatoes and special needs that tomatoes have. In later columns, I will discuss problems with fruit set, insects, diseases, and physiological problems. In the meantime, if you would like more information, please give us a call and ask for Guide sheet G6461, "Growing Home Garden Tomatoes."

Part 2: Fertilizing Tomatoes

Once you have selected a tomato variety for your home garden, you next need to select a site where they will thrive.

As with most garden plants, tomatoes do best on a well-drained soil. This not only keeps the soil from becoming waterlogged, but it allows good aeration in the root zone. Heavy soils which do not drain well should be avoided, because this can lead to root diseases and other problems.

Tomatoes prefer full sunlight. Having said that, if your yard does not have a spot that receives full sunlight all day long, just pick the sunniest spot you can find. A little shade won’t hurt, but the more sunlight, the better.

Some plants may cause toxic reactions to tomatoes. The classic bad mix is black walnuts and tomatoes. The roots of black walnuts produce a compound called juglone, which is toxic to many kinds of plants, including tomatoes. So it’s best to keep your tomatoes at least 50 feet away from the drip line of the tree.

You may want to improve the soil in your garden site by adding leaf mold, well-composted manure, or similar organic amendments. However, some caution is in order. I have seen situations where people have added a lot of manure, thinking it would grow big tomatoes. Well, it did grow big tomato plants, but few tomato fruits. The reason was that it was actually adding too much of a good thing. Under very high fertility, tomatoes produce a lot of vegetation, but do not set fruit well. So take it easy on those organic amendments.

You may need to add lime, but then again, you may not. This is where a soil test is really a good idea. It will tell you the nutrient status of your garden site, as well as the soil pH. If your pH is already high enough, adding lime is not a good idea, and may make the situation worse. A soil test is something that I always recommend. Tomatoes need a pH of 6.5 to 7.0. Ideally, lime should be added well before you plant, so it has time to affect the soil pH.

Your soil test will also give you an idea of how much nitrogen, phosphorus, and potassium should be used. It’s best not to randomly add fertilizer. I have seen soil tests come back to my office with P and K off the charts. That’s not a good situation, and if you add more P or K, you’re not helping yourself.

One other nutrient that a soil test will report on is calcium. Tomatoes are subject to a physiological condition called blossom end rot. This is caused by a calcium deficiency in the fruit. This may or may not be due to a low calcium level in the soil, and again, this is where the information provided by the soil test really helps. If you need to add lime, you will get some calcium there, but if the pH is already too high, you will need to add gypsum instead. The soil test will tell you which one and how much. You also may have plenty of calcium. In this case, there are other causes leading to blossom end rot. I’ll cover those in a future article.