Setting Your Tomatoes Up for Success

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With our last fronts (hopefully!) behind us, it’s finally time to begin planting warm-season fruits and vegetables. Among summer garden crops, tomatoes are some of the absolute most popular, but also the most prone to any number of problems.

hand picking tomato. Image Credit: Laurel Babcock

Image Credit: Laurel Babcock

This doesn’t mean you can’t have your very own bumper crop of delicious, home-grown tomatoes. Cultivating a healthy tomato crop begins with following best planting practices for the Piedmont. Keep the following tips in mind as you plant this spring to maximize your chance of having more tomatoes than you know what to do with.

Plant in The Right Place

Like most vegetables, tomatoes grow best with eight hours or more of direct sunlight each day and when they are planted in soils with good drainage or in raised beds. Prepare your soil before planting by spreading two to four inches of compost, aged manure, ground pine bark, or leaf mold over the surface and tilling it into the top six to eight inches. Remember, organic matter is eaten by the microbes in our soil very quickly – plan on adding organic matter every year for your soil’s health.

For our mostly acidic soils, mixing lime in when you till will improve tomato growth and help prevent blossom end rot. The best way to find out if your soil needs lime and other nutrients is to submit a sample for testing to the N.C. Department of Agriculture and Consumer Services. Soil sample supplies are available at the N.C. Cooperative Extension, Durham County Center and samples can be returned there for delivery to the NCDA&CS Agronomic Lab. Even in the absence of lime, adding organic matter will help improve soil structure and create a better growing environment for your tomatoes.

**note: The N.C. Department of Agriculture and Consumer Services Agronomic Lab is not currently accepting routine soil samples, but keep soil testing in mind for the future.

Plant Early

Tomatoes grow and produce best when daytime temperatures range from 70 to 80 degrees, and night temperatures fall between 60 and 70 degrees. Most of our summer days exceed these spring like temperatures, which causes tomato plants to shed their blossoms without setting fruit. Fruits that do ripen when daytime temperatures reach into the mid-90s have less flavor, ripen unevenly, and may develop hard white areas inside the flesh. Planting tomatoes as early as possible will give plants more time to grow and produce under ideal temperatures before the hottest part of summer. In addition, tomato plants struggle even more with diseases during our hot, humid summer. Early planting allows you to ensure some fruit set before high temperatures or disease get the best of your plants.

Plant Deep

Tomatoes are one of the few vegetables that have the ability to produce roots along their stem. Setting the root ball two or three inches deeper than soil level at planting time will result in plants with larger, more extensive root systems. Be sure to remove any leaves that would fall below the soil line, and even ones that easily touch the soil. If you have plants with long leggy stems do not bury the root ball several inches deep. Instead, dig a shallow trench and plant them lying sideways, so the leggy part of the stem is planted horizontally two to three inches below soil level.

Space tomato plants at least three feet apart and plan for a way to physically support plants as they grow (e.g. cages, trellising, etc.). Mulching the soil underneath and around tomatoes will help keep soil moisture even, soil temperatures cool, and prevent soil (and soil-borne diseases!) from splashing onto lower leaves.

Help Prevent Soil-Borne Diseases

Many of the fungal and bacterial diseases that plague tomatoes start in the soil and are splashed onto leaves by water droplets, either from rain or watering. When planting tomatoes, be sure to remove all lower leaves that easily touch or even rest on the soil. As the plants grow up, continue to remove lower leaves, keeping a healthy buffer between the top of the soil and the lowest leaves. Plants can also be mulched with untreated grass clippings or other organic matter to help prevent soil from splashing onto lower leaves. When watering, water near the soil level to prevent getting leaves wet (creating a perfect environment for diseases) and splashing soil onto lower leaves.

At the time of planting and until plants are well-established with a good buffer between the lower leaves and soil level, consider regularly applying a copper fungicide. Copper is an organic option for control of many fungal and bacterial diseases, and is readily available online, at garden centers, and at big box stores. Be sure to always read and follow the label, and to reapply following rain. Properly applied, copper can be one of the single best ways to prevent early leaf-based diseases on tomatoes.

Plant Several Varieties

There are hundreds of tomatoes varieties available, with dozens of new varieties introduced each year. Give yourself the best chances of success by planting several different tomato varieties. Two major things to consider are whether to choose heirloom or hybrid varieties, and whether you prefer determinate or indeterminate plants. Also bear in mind that for many tomato varieties, the larger the fruit the more finicky they are to produce.

Heirloom varieties have been in cultivation for generations, with seeds saved and passed on from one year to the next. Many heirlooms are regionally adapted and not all produce well in the south. Some heirlooms adapted to southern heat and humidity include ‘German Johnson’, ‘Marglobe’, ‘Cherokee Purple’ and ‘Homestead.’

Hybrid varieties offer the benefit of increased disease resistance. ‘Celebrity’, ‘Early Girl’ and ‘Better Boy’ are reliable hybrid tomatoes for the south. All three produce medium to large size fruits and are resistant to fusarium, one of the common soil-dwelling diseases that causes tomato plants to wilt. ‘Celebrity’ and ‘Better Boy’ are also resistant to root knot nematodes. Planting disease-resistant hybrid varieties will increase your chance of success, but keep in mind no one tomato variety is resistant to all, or even most, of the diseases that commonly plague this popular crop. Newer disease-resistant hybrids developed by NC State for North Carolina conditions include ‘Mountain Pride’, ‘Mountain Fresh’, ‘Fletcher’ and ‘Mountain Magic’.

Determinate varieties stop growing once they reach full size, which is usually three to four feet tall. These plants set all their fruit at once and typically bear tomatoes over a four to five-week period and then are done. Due to their smaller size, determinate varieties work well in containers and are also favored for canning since they bear a heavy crop that ripens in a short period. Many modern hybrids and bush varieties are determinate. For especially small spaces like patio containers, consider dwarf varieties.

Indeterminate varieties continue to grow all season, setting successive crops of fruit all summer and into the fall, if you can keep pests away. Because they keep growing, indeterminate varieties get large, often six feet or more, and need sturdy support systems. They often easily outgrow many commercially-available tomato cages. Indeterminate varieties are popular among home gardeners because they bear over a long season.

three plates full of tomatoes of various sizes and types

The wonderful windfall of a good tomato year. Image Credit: Sue Kadwell

Many heirloom tomatoes are indeterminate, as are most cherry tomatoes. Cherry tomatoes are some of the easiest to grow and every garden should include at least a few of these highly productive plants that yield dozens of small fruits on long trusses. Gardener’s favorites include ‘Sungold,’ ‘Super Sweet 100,’ and ‘Juliet’, though to be honest I have never seen a cherry tomato that did not thrive.

Practice Crop Rotation

If you have room, plant tomatoes in several different spots around your yard, rather than all together in one bed. This will lessen the chance a pest or disease will attack your entire crop. Another practice that helps minimize pest pressure is crop rotation. To practice crop rotation, avoid planting tomatoes in the same location year after year. In addition, do not plant tomatoes in the same location where peppers or eggplant grew the previous year. These crops are in the same family as tomatoes and host the same pests and diseases.

If you have had problems with tomato wilt diseases in the past, consider planting in large containers filled with potting soil. Whether you plant in containers or garden beds, apply a slow-release fertilizer according to the label when you plant. Slow-release fertilizers include organic fertilizers such as Plant-tone as well as time-release products such as Osmocote. Supplementing plants with liquid fertilizers such as compost tea for the first few weeks after planting will help them establish quickly, but there is no need to liquid feed plants all season. In fact, over fertilizing with nitrogen reduces fruit set and encourages blossom end rot.

Want to learn even more about setting your tomatoes up for success?

Check out these excellent resources:

North Carolina Extension Gardener Handbook – This excellent publication from NC State University was written specifically for North Carolina, and has chapters on almost every topic a gardener could want. Learn more about Vegetables GardeningOrganic Gardening, and Pest Management.

Growing Home Garden Tomatoes  – All you could want to know about growing tomatoes in the home garden from NC State Extension.

Central North Carolina Plant Calendar for Annual Vegetables, Fruits, and Herbs – A comprehensive calendar of when to plant warm and cool season fruits and veggies, tailored to our region.

Adapted from Tomato Planting Tips, by Charlotte Glen, State Coordinator, NC Extension Master Gardener Program