As a home gardener I look forward every year to the end-of-summer crop of tomatoes.
Last summer, though, my plants were spindly and unhealthy, and hit hard by blight. The crop was paltry. I wondered what I should do differently this year to help my tomato plants thrive.
Since many home gardeners are now putting tomato plants in the ground or into pots, I called some of the most experienced farmers in the Upper Valley, all of whom grow scores of varieties of tomatoes, to ask for their best advice on how to get the most out of your tomato plants.
Turns out I should be sued for criminal tomato negligence. While I didn’t kill my tomato plants outright, I didn’t nurture them either.
There are easy, common-sense tips on how to improve your tomato crop, from selecting the variety of tomato to improving the soil, to giving them adequate room to grow. This isn’t an exhaustive list of recommendations, but it’s a start for those of us who want to grow happier plants and more flavorful tomatoes.
You need to start with whether your tomatoes are determinate or indeterminate, which will dictate how you care for them.
Determinate tomatoes are compact, bush-type plants that grow up to 4 feet. They are self-contained enough to need only caging, not staking or trellising, and they grow well within pots or containers.
Determinate varieties “put a bunch of growth on and go through the reproductive cycle all at once,” said Pooh Sprague of Edgewater Farms in Plainfield.
In other words, you’ll get a slew of tomatoes all at once, usually within a two-week period, which makes them ideal for commercial growers and canners, as well as home canners, Sprague said. After the frenzy of fruiting and ripening, the plant begins to die back. Examples of determinate tomato varieties include the popular Rutgers, the paste tomato Roma and Bush Early Girl, which is a relative of the prolific Early Girl.
Indeterminate tomatoes grow more like vines than bushes, Sprague said. They keep growing throughout the season, and will produce fruit until frost. Some hybrids, like the commonly found Jet Star, are indeterminate. All heirloom varieties, such as Brandywine, Prudens Purple and Cherokee Purple, are indeterminate and tend to produce less fruit than determinate varieties.
“They became heirlooms for a reason,” said Dave Chapman of Long Wind Farm in East Thetford. “They tend not to have greater disease resistance and have a shorter life.”
But many heirloom varieties also have the depth of flavor that some modern varieties lack, which is why gardeners seek them out.
Still, Sprague said, “there’s also something to be said for spreading your risk.”
Although many gardeners have turned back to heirloom varieties, be aware that they do not always produce as consistently as newer hybrid varieties. So plant both determinate and indeterminate varieties for a good mix, and think about planting slicing, cherry, paste and good-eating tomatoes.
Regardless of whether you are buying determinate or indeterminate plants, said Carol Stedman of Clay Hill Corners Farm in Hartland, look for a plant with a healthy root system that isn’t root-bound in its container.
If you see flowers or early fruit on a plant you’re buying, remove them because you want the plant to produce more fruit later on, rather than expending its energy on these fruit that appear early.
For Suzanne Long of the organic Luna Bleu Farm in South Royalton, soil health is key to tomato health. “You want to start out with a good organic soil,” Long said.
Sprague is often asked by gardeners what they should add to soil to make it a better environment for growing vegetables. His answer is: “You really need to take a soil sample. Soil is a combination of biology and chemicals. You’ve got to know what you’re playing with: it’s a chemistry set.”
An agricultural county extension agent can analyze a soil sample for you and suggest what, if any, amendments are needed to create the kind of soil that tomatoes like, Sprague said.
Too much nitrogen in the soil will produce a leafy plant but not as many fruit, and it’s the fruit that you want, said Long.
Don’t use raw manure or compost on your garden plot: composted manure or aged compost are ideal. You can also fold in granular organic fertilizer found at a garden center to ensure a slow release of nutrients through the season.
For home gardeners with limited space, rotating tomatoes from spot to spot may prove challenging. But planting tomatoes in the same spot year after year is a problem, Sprague said. It can lead to build-up of disease and early blight.
If you can rotate your tomato plants you reduce the likelihood of disease and the incidence of the tomato hornworm, which can decimate a plant in a matter of days.
Also, Sprague said, plants extract nutrients from the soil and if you grow them in the same area year after year without also fertilizing you’re depleting the soil of all the nutrients that helps tomatoes grow.
The first rule is: allow your tomato plants plenty of room.
At Luna Bleu, the gardeners plant tomatoes 18 inches to 2 feet apart, with nothing in between, with the possible exception of basil, Long said. The more that air circulates, and the more light a plant gets, the higher the chances of getting a good, healthy crop.
“If you crowd the plants, the fruits get smaller,” Chapman said.
Plant tomato seedlings deep in the ground to encourage good root growth. If a tomato plant is too leggy, you can plant it even deeper or lay the root ball and stem on its side so that it grows up with more support.
Indeterminate tomatoes, in particular, really need a “lot of space,” Chapman said.
As they grow they need to be staked so they don’t flop onto the ground, where they are more susceptible to diseases in the soil. Staking them also protects them from splash-up from rain and watering, which also contribute to spreading disease.
Another rule of thumb, said Stedman, is to select a stem that looks like a clear leader, or two stems that look like leaders, and then remove the “suckers.”
A sucker is a shoot that emerges from the joint where a branch on a plant meets the main stem. Suckers grow into weaker stems, add too much foliage, produce inferior fruit and take energy, light and air away from the plant’s main objective: to grow large, healthy tomatoes.
To keep down weeds, reduce disease, and retain moisture in the soil, Long recommends mulching with straw around the base of the plants, or putting down plastic. You can also use a floating row cover, available from most garden centers or catalogues, which admits water, air and light, but keeps out insects.
Pruning your plants throughout the season is a critical part of promoting good growth. Keep removing suckers as they appear. It’s also useful, Long said, to remove the leaves closest to the ground because they are not doing much photosynthesizing. Doing so increases the air flow.
Prune the tomato hornworm, too. This beast of an insect will chomp rapidly through a plant. It leaves behind tell-tale droppings that alert you to its presence, if you haven’t seen it on the plant. If you have chickens, they will happily eat all the hornworms you can catch.
Once the tomatoes bear fruit, you don’t want to overwater them, because it affects their flavor. “If you hold back the water, the fruit gets smaller but better tasting,” Chapman said. Once the tomatoes actually begin changing color, you can stop watering altogether because dryer plants concentrate flavor, Long said.
With indeterminate varieties Sprague harvests ripe fruit from the bottom up. That’s not necessary with determinate varieties, which ripen in a short period of time.
Nicola Smith can be reached at nsmith@vnews.com.