April 11, 2020
When it comes to selecting tomato plants for your summer garden, the choices can be overwhelming. Should you go with hybrid or heirloom, determinate or indeterminate, cherry or standard size? What about early or long season? Then there are those confusing disease resistance codes. The number of options to consider can make your head spin!
While some tomato choices such as taste, color, and size are a matter of personal preference, other selection criteria should be determined by growing conditions. Most important among these is the microclimate in your garden. Tomatoes like it warm and sunny with a bare minimum of 6 hours of sun per day and a soil temperature above 55 degrees. “Days to Maturity” on the plant label, is an estimation of the number of warm and sunny days from planting to first fruit. This timing is climate dependent and cool days and nights will slow the growth of the plants and increase the time to maturity. In cooler areas of Marin, a tomato variety labeled as 75 “Days to Maturity” may actually require many more calendar days to achieve the required number of warm and sunny days. This means that, in some foggy or windy Marin gardens, the tomato varieties with the greatest number of “Days to Maturity” (80 or more days), will not have time to produce ripe fruit before the onset of fall weather. You can avoid this disappointment by selecting tomato varieties recommended for your garden’s microclimate.
Although tomato plants are available in local nurseries as early as March, there is little benefit to outside garden planting earlier than late April. The plants are not likely to show much growth until those warm and sunny days begin. You might be able to provide some protection with plastic mulch and floating row covers, but that “Days to Maturity” requirement still applies no matter when the plants go in the ground.
Once you have narrowed down the best tomato varieties for your garden’s microclimate, you can consider some of the other information on the plant labels. Most popular tomatoes for home gardens are indeterminate varieties that produce vines that will grow and set fruit continuously until they are killed by frost or disease. However the determinate varieties, which have a shorter fruiting season, are more compact and can work better in containers. The hybrid versus heirloom question is largely a matter of preference. The exceptional flavors, beautiful colors, and unique shapes of the heirlooms are hard to resist, but they tend to be more prone to disease and the yields can be less than the hybrids. Hybrids, on the other hand, have been developed for greater predictability in taste, size, yield, and disease resistance. If diseases have been a problem in your garden, you will want to make resistance a priority in your plant choice and look for the letters on the label following the tomato cultivar name to indicate the diseases for which resistance has been determined.
Finally, you want to start with the healthiest plants. Most of us choose to buy young plants rather than start our own from seeds. The best tomato plants for transplanting are compact seedlings with sturdy stems and four to six leaves. Avoid plants already bearing blossoms or fruit because they will grow less vigorously after transplant since they have already begun to divert energy into flowering. Although the annual Tomato Market had to be canceled this year, much more information about selecting and growing tomatoes is available on the Marin Master Gardeners’ public website at marinmg.ucanr.edu.
If you look forward to savoring juicy, ripe, homegrown tomatoes this summer, then plan now to start with the right plants. Don’t be taken in by descriptions of large, flavorful varieties that won’t stand a chance in your Marin garden. Instead, pick the healthiest young plants you can find among the types already shown to do well in our cooler temperatures and shorter growing seasons and enjoy the tasty rewards of your efforts.