By Steve Reiners, Professor and Chair, Horticulture Section, Cornell University, Cornell AgriTech. This is part of a series of columns that he wrote about vegetable gardening during the pandemic that ran Spring-Summer 2020. Read more articles from 2020 | Read later articles in this series.
June 12, 2020
There are two ways to grow tomatoes, upright with support or sprawled on the ground. For gardens, I always recommend growing them upright. It saves space, reduces disease, and gives you more useable fruit with less rot. Growing them upright allows you to prune the plants and keep their size manageable.
Pruning is the selective removal of the “suckers.” These are the side shoots that grow from the crotch above where leaves are attached to the stem. By removing suckers, you remove some of the potential fruit, but you keep the plants more manageable. Instead of 30 fruit from a plant you may get 25, but the fruit will be slightly larger by an ounce or two.
Determinate or indeterminate?
Tomatoes have two types of growth habit, determinate and indeterminate. Knowing which type you have is important.
Determinate varieties are relatively small, bushy and compact. Each branch ends in a flower cluster and fruit tend to ripen over a 3- to 4-week period.
Contrast this growth habit with indeterminate varieties, the large plants in most home gardens. These produce plants as large as you allow them to grow. They have many widely spaced branches and numerous suckers and produce fruit all season long.
To prune or not to prune?
Determinate types can be pruned lightly. Any pruning removes a finite number of blossoms and fruit. If you prune all the suckers on a determinate type, you will have a short plant with few fruit. Indeterminates will produce suckers all season long, so these can be pruned heavily.
What’s a gardener to do? You can grow great tomatoes without pruning, but if you want to prune, here are a few guidelines.
For determinate types, don’t bother pruning. It will only reduce your harvest.
For indeterminate types, allow one, two, or three suckers to grow from the base of the plant. Clip or snap off the rest. It’s helpful to find the first flower cluster on the plant. It will be small but obvious. Always leave the first sucker below the flowers. Then it’s up to you whether you want to leave one or two more suckers below the first. Each of these will become main stems with lots of fruit
Remove suckers below these and any above the flower cluster. The best time to remove the suckers is when they are 2 to 3 inches long. If larger, you can sometimes damage the main stem.
Your carefully suckered plants will need support, and there are many ways to hold them upright. Some gardeners use a single stake at each plant and tie the plant with twine to the stake as it grows, about every 8 to 12 to inches.
Tomato cages -- large sturdy cylinders made of wire mesh -- are another popular method to support plants. Just make sure you buy the sturdiest cage you can. The method I prefer is one many commercial growers use called the Florida Weave. With this method, you place a stake between every other plant and at each end of the row, instead of at each plant. Use a 4- to 6-foot stake driven into the ground at least 8 to 12 inches deep. When the plants are about 10 inches tall, they need to be “strung” for the first time. For string, use lightweight, thin plastic string, which works better than jute or cotton.
To start, tie one end of the string to the first stake in the row, about 9 to 10 inches above the ground. Pass the string along the left side of the first tomato plant and the right side of the second. As you get to the second stake, wrap the string around it and continue down the row in the same fashion. When you reach the last stake in the row, wrap the string around it and work your way back, weaving in the opposite direction.
Between each stake, the twine should be in the shape of a figure eight as you look down from the top. This holds each plant in place. Repeat the process in a couple of weeks as the plants grow, with the strings spaced every 10 to 12 inches apart. For the rest of the stringings, there is no need to make the figure eight. Just run the string up one side and down the other. It’s very simple.
You can set up the Florida Weave right now and then just train the plants between the strings as they grow. That way the trellis is ready to go, and you avoid the hassle of trying to wrap string around plants that have grown too big.
This week in the garden
- Keep weeds under control. Now’s a good time to apply mulch.
- Onions that are flowering should be pulled out. These won’t produce a bulb and will only take up space.
- Last chance to plant tomatoes, peppers and eggplant. Later plantings won’t mature before the first frost.
Rains continue to be hit or miss. Keep your garden well-watered. We need about one inch of water per week, either from rain or irrigation. That translates to about 6 gallons for every 10 square feet. It’s a good idea to keep an inexpensive rain gauge in the garden to track rainfall. You can also use buckets or cans to collect the water. Then use a ruler to measure the amount.