Plant Tomatoes in Trenches for Better Results

Ensure healthy, successful tomato plants in your vegetable garden by planting half or more under the soil in a trench. Learn how and why.

Everyone plants tomatoes. Well, everyone who vegetable gardens, that is, or at least that’s how it seems. Tomatoes are the gateway drug to edible gardening. Once you’ve had one season of healthy plants with an abundant harvest of luscious tomatoes, you’re totally hooked. But what if you don’t? What if your tomato plants are limpy and wimpy and succumb to the diseases or pests that plants are so susceptible to in the heat of summer? Then you may give up altogether and go back to buying all your tomatoes in the grocery, and I just can’t have that!

So, I’ll tell you a little secret, one that stingy gardeners keep to themselves. Listen up: It’s all in the roots. This is true for most plants in your garden, but for tomatoes it’s especially true. Tomatoes need a good base to grow up tall and strong and to support all the weight of that yummy fruit. Indeterminate types that keep on growing until frost need this strong base even more. One way to ensure healthy roots is to focus on your soil first—after all, that’s where the all-important roots take up all those nutrients to feed the plant.

Another trick seems totally counter-intuitive, but it works. When planting tomatoes, bury half the plant or more. Yep, it’s true. While for most plants, you can use the container you’re transplanting from as a guide for how deep to plant, for tomatoes, you should bury at least half the stem. If you want, you can trim off the existing leaves and branches along the bottom half of the stem, but I usually just bury the plant stems and leaves and all. Under the ground, those stems will magically become additional roots that will support your plant, both physically and nutritionally.

One way to plant tomatoes deeply is to dig a deep hole and drop the plant in with only the top half or third above ground, then cover the lower stem up. I learned this method while working for Bonnie Plants, where our motto was “Plant tomatoes deep.” Another method is called trenching tomatoes. This involves digging a long trench, again with the top third above ground but with the rest of the plant laying sideways. While there’s very little debate about whether tomato plants should be sunk half or more underground, I’ve heard seasoned gardeners debate, in the field even, about whether the best practice is to plant in a deep hole or to using the trenching method. I’d say that either way, you’re in for a better harvest.

Okay, so now you know the secret. Ready to plant? Here’s a little tutorial on planting tomatoes in trenches, from my garden this week.

Step 1. I started with a large, healthy plant. This tomato plant is Lizzano, a cherry tomato variety that is an All-America Selections winner. Lizzano doesn’t get very tall and is great for small gardens and containers. While a friend grew this from seed for me, you can find Lizzano and its cousin, Terenzo, in many seed catalogs and as transplants in your local garden center. 

Step 2. My plant was already about 14 inches tall, so I needed to dig a long trench. If you start with a smaller plant, you’ll dig a smaller trench. I dug down about 4 inches and about 12 inches across to accommodate about half the plant and its current root structure.

Step 3. Here, you can see the tomato plant laying in the trench, with the roots at the end of the trench and part of the green plant laying sideways. All of that sideways plant was soon covered with soil. The buried branches and leaves will become roots under the soil. You can trim off the stems that will be buried if you want, but I don’t. Cuts along the stem create plant wounds that can invite diseases and pests to enter the plant, so why bother and take the risk? 

Step 4. After the tomato is covered, you can see about half the plant stem now above ground. Because you plant part of the tomato sideways, you must help bend the stem (very carefully!) to come up vertically above ground. You can see here that the stem is coming out of the soil at a slight angle. This is another reason some gardeners swear by trenching tomatoes—forcing the plant to work at an angle gives it strength. It’s kind of the gardening version of the old “strength through adversity” or “that which doesn’t kill us makes us stronger” cliché. 

Step 5. Now that your plant is tending sideways, it’s extra important to provide support. Because Lizzano is a shorter plant, I felt comfortable using a standard 30-ish-inch tomato cage. For taller tomatoes, I use something much more hefty. 

Bonus: This isn’t part of the tutorial at all, but I threw it in here anyway. I love seeing beneficial insects like ladybugs on my plants. Ladybugs will help you take care of the aphids, if you’re unlucky enough to have an aphid invasion. Ladybugs are on your side. So, with the strong root system plus beneficial insects, I have a feeling this tomato plant is gonna be a great garden success!

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