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Tomato plants are incredibly easy to propagate from cuttings. By simply pruning healthy suckers from the plant and transplanting them in soil, you can double or even quadruple the amount of plants – and tomatoes. Photo courtesy of Joe Urbach

Growth in Gardening: Pruning Tomato Plants

Sunday, July 15, 2018

Ahh, July, we complain about the heat, lack of rain and humidity, but the most amazing complaint I here now is, “My tomato plants are too big!” Yep, some gardeners are complaining that their garden tomatoes are too successful. While this may sound a bit crazy, I do understand. Sometimes our tomato plants get so large and unwieldy that we can’t help but wonder, “Should I prune my tomato plants?” This question is rapidly followed by, “How do I prune tomatoes?” Let’s look at these two questions and then a way to put those pruned bits to good use.

“Should I cut-back my tomato plants?” The answer to this question is a personal one. Some people avow resolutely that pruning tomato suckers improves the production and health of a plant. Others claim that pruning tomato suckers damages the plant needlessly and even opens the plant up to disease while it does nothing to help the plant. Scientifically speaking, who is right? A study at Iowa State University in 2010 showed that pruning suckers sometimes, but not always, made a difference in fruit size and disease. The study did not find pruning tomato suckers ever helped with the yield of the plant.

So much for science. On an anecdotal level, I know many Texas Master Gardeners recommend pruning tomato plants. But, on a personal level I can tell you that I am one Texas Master Gardener that will only prune my tomatoes back to keep the walkways in my garden clear. So, what it boils down to is this, the decision to prune or not to prune is one that you will have to make for yourself. It is not likely to either help or hinder your tomatoes. If you want a tidy garden that is just “perfect,” then go ahead and prune. On the other hand, if you don’t mind a garden that has a more natural and slightly “wild” look to it, don’t cut anything back. Or even cut back some and while allowing others to “go nuts,” like I do.

If you do decided to prune, you need to make sure that you do it the correct way to help reduce the chances of disease.

  1. Do not start pruning tomato plants until they get at least 1 – 2 feet tall. Any smaller than this, and the plant may not recover from the shock of being pruned.
  2. At this size, the plant will have branches coming off the main stem that you decide must to go. Where these branches meet, you will see and additional branch growing. This is called a tomato sucker.
  3. Using a sharp, clean pair of pruning shears, snip these small sucker branches off.
  4. The best time to prune tomato plants is in the early morning on a dry day. This will allow for the wounds from the pruning to heal cleanly and will reduce the chances of the plant being infected by disease.
  5. If you choose to prune tomato plants, make sure that you use watering methods that water the tomato plants at the soil level (like soaker hoses) rather than from above (like sprinklers). This will prevent the splashing of soil up onto the tomato plant and the tomato plants wounds.

Your answer to the question of, “Should I prune my tomato plants?” is your own, but now, at least you have some additional information on why and how to prune tomato plants.

But if you do prune your tomatoes what should you do with the bits you cut off? One answer is to cut them into small bits and add them to your compost pile, but you could root them. Many of us have started new houseplants from cuttings but did you know that many vegetables can be started in this manner too? Tomato propagation by cuttings is a perfect example and very easy to do, cuttings can be rooted in water or directly in the soil.

Why would you want to root cuttings of tomato plants you are cutting back? Well, first off you may want to give some away as gifts or you may trade some of your cuttings with another gardener for new varieties that they have that you want to try growing. Heck, if you admire a neighbor’s lush tomato plant, starting tomato plants from cuttings is an excellent way to clone their plant and, hopefully, get the same vigorous result in your garden; just be polite and ask first before you snip from their prized plant.

Rooting tomato cuttings is cost saving as well. You can purchase a couple of plants and then root additional ones from the cuttings. Just for fun last year I purchased a pack of seeds for a dollar, they were labeled simply as “Roma” tomatoes. The pack contained 16 seeds, I planted them and 14 sprouted. As they grew I took cuttings and rooted the cuttings over and over again. Eventually I had 126 four-inch pots growing those “Roma” tomato plants that all came from cuttings. I also had the original 14 plants that had grown from seed. So, that one dollar I spent on a seed packet produced 140 tomato plants in all – I could have gotten even more too but my wife (correctly) pointed out that my tomato project was getting out of hand.

Tomato cuttings are amazingly fast and easy root growers. To begin, look for some of the sucker shoots on the chosen tomato plant that don’t have buds on them. With sharp pruners, cut about 6-8 inches of the sucker or new growth at the tip of the branch. Then, you can simply immerse the tomato cutting in water or plant it directly into some soil medium. In water, the cutting should root within about a week and will be ready to transplant.

Roots will be stronger, however, if the cuttings are allowed to root in soil, so that is the route I take. It’s easy, take your 6- to 8-inch cutting and clip off any flowers or buds and snip off the bottom leaves, leaving only two leaves on tip of the cutting. Put the cutting in water while you prepare the soil. You can root in peat pots, 4-inch containers filled with damp potting soil or even directly into the garden. Make a hole with a pencil for the cutting to slip easily into and bury it up to where you cut off the lower leaves.

Put the cuttings in a warm, but shaded area, being sure to protect them from the scorching heat and direct sun. Keep them moist for a week to acclimate them and then gradually expose them to stronger light until they are finally in the sun for most of the day. At this point, you can transplant them into their permanent location.

Tomatoes are perennials and can live for years in warm climates. However, they do not fruit in their successive years nearly as well as in the first year. This is where overwintering tomato cuttings for spring clones comes into play. Just follow the above instructions up to transplanting the cuttings into a larger pot and keep in a warm, sunny room to overwinter until the spring.

Voila, tomato propagation couldn’t be easier. Just remember to take cuttings from plants that have the best yields and tastiest fruit, as the cuttings will be a virtual clone of the parent and, thus, retain all its characteristics. Propagating tomatoes is a great family activity so get the kids involved. They’ll have fun and might just develop a life-long love of gardening too.

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Joe Urbach is the publisher of GardeningAustin.com and the Phytonutrient Blog. He has lived in the Central Texas area for over 30 years. Urbach is a certified Texas Master Gardener from Hays County and is currently serving as the director of training. For more information on the Master Gardener program contact the Hays County AgiLife Extension Service at 512-393-2120.

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