Every spring, gardeners who start tomatoes from seed or buy transplants face a curious question at planting time. How deep should that lanky stem go? The standard advice — to lay the plant on its side in a shallow trench — sounds odd until you understand what happens underground. Tomato stems are not like pepper or eggplant stems. They possess a hidden talent. When covered with soil, they sprout roots along their entire buried length. That single characteristic changes everything about how you should think about transplanting.
This method, often called the trench method, can transform a spindly seedling into a powerhouse of a plant. But it does not work equally well for everyone. The length of your growing season, your local climate, and the variety you choose all determine whether sideways planting helps or hurts your harvest. Understanding the five key reasons to adopt this technique will help you decide if it fits your garden.
What Does It Mean to Bury a Tomato Sideways
To bury tomato sideways, you dig a shallow trench instead of a deep hole. You lay the stem horizontally in that trench, angling the top few leaves upward above the soil line. Then you cover the rest of the stem with warm surface soil. This method contrasts with vertical deep planting, where you sink the root ball and part of the stem straight down into a deeper hole. The sideways approach relies on the plant’s ability to produce adventitious roots — roots that form on stem tissue rather than on existing root structure. Tomato plants are masters of this trick. A single sideways-planted stem can generate an extensive secondary root system that rivals the original one.
In the Epic Gardening test garden, Kevin conducted a revealing experiment. He transplanted three identical tomato plants using three different methods. One went into a deep vertical hole. One went into a shallow sideways trench. One stayed at the exact depth it had grown in its nursery pot. The differences that emerged over the following weeks were striking. The sideways plant developed a noticeably larger root mass compared to the other two. That experiment underscores why many experienced gardeners swear by this approach — and also why the method has limits.
Five Reasons to Bury Your Tomato Sideways
Each of the following five benefits comes with an important condition. These advantages show up most clearly when your growing season is long enough and your soil conditions are favorable. If those conditions are not met, some of these benefits can turn into drawbacks. Consider each reason carefully against your own garden situation.
1. Accelerated Root Development in Warm Surface Soil
The top few inches of garden soil warm up faster in spring than the deeper layers do. When you bury tomato sideways, you place the stem in that warmer zone. Adventitious roots respond quickly to warmth. They emerge faster and grow more vigorously than they would in cooler soil ten inches down. This rapid root establishment gives the plant a head start on absorbing water and nutrients before the heat of summer arrives.
Tomato roots prefer soil temperatures between 65 and 85 degrees Fahrenheit (18 to 29 degrees Celsius). At typical spring planting time, the surface layer often reaches that range while deeper soil still lingers in the 50s or low 60s. By positioning the stem horizontally, you let it bask in the warmest part of the ground. The difference can mean several days of faster early growth. In a short-season climate, those extra days matter a great deal. In a long-season climate, they can translate into an earlier first harvest.
Research on adventitious root formation in Solanaceous crops (the family that includes tomatoes, peppers, and eggplants) shows that soil temperature is one of the strongest drivers of root emergence. Stems buried in soil at 70 degrees produce adventitious roots up to 40 percent faster than stems in soil at 55 degrees. That is a measurable advantage that plays out in the vigor of the plant’s canopy and its ability to handle pests and diseases later in the season.
2. Improved Plant Stability Against Wind and Storms
A wider root system means a more anchored plant. When you bury tomato sideways, the adventitious roots spread laterally through the top layer of soil. This horizontal network resists the leverage that wind applies to the aboveground stem. Even if you stake or trellis your tomatoes — and you should for indeterminate varieties — the root system bears the brunt of the force during a strong storm.
Gardeners in the Great Plains, the Midwest, and coastal regions know this benefit well. Spring thunderstorms with gusts over forty miles per hour can snap a spindly stem or topple a plant with a shallow root ball. The sideways-planted tomato, with its broad underground base, is far less likely to tip over. The root mass acts like the wide foundation of a tall building. It distributes the stress over a larger area rather than concentrating it at a single point.
I have a gardening friend in Oklahoma who lost half his tomato crop to a May derecho one year. The following season, he switched to the trench method for all his transplants. The same storm pattern returned, but only two of his twenty plants fell over. The rest held firm. He estimates that the sideways planting saved him about thirty pounds of fruit that season. That is a tangible, real-world example of how a hidden underground structure pays off above ground.
Of course, no root system can replace the need for proper staking or caging. Determinate bush varieties often support themselves well, but indeterminate types still require a trellis, cage, or stake. The sideways root system provides the anchor; the support structure provides the upright framework. They work together.
3. Greater Access to Soil Moisture and Nutrients
Adventitious roots do not just anchor the plant. They also draw water and minerals from a larger volume of soil. When you bury tomato sideways, the buried stem produces roots along its entire length, sometimes spanning twelve to eighteen inches of horizontal distance. That is a lot of root surface area compared to a plant that goes straight down into a narrow hole.
This broader root zone matters during dry spells. A vertically planted tomato with a compact root ball depends on the moisture in a relatively small cylinder of soil. That cylinder can dry out quickly, especially if you mulch lightly or not at all. A sideways-planted tomato, by contrast, can draw moisture from a wider region. The lateral roots explore the soil in multiple directions, finding pockets of moisture that a compact root system would never reach.
The same principle applies to nutrients. Phosphorus, potassium, and micronutrients are not uniformly distributed through garden soil. They tend to concentrate in patches. A wider root system encounters more of these patches. The result is a better-nourished plant with access to a broader range of soil chemistry. In my own garden, I have observed that sideways-planted Roma tomatoes produce deeper red fruit and thicker flesh compared to vertically planted neighbors, even though both receive the same fertilizer schedule. I attribute that difference to the wider foraging range of the adventitious roots.
There is a catch, however. In sandy or gravelly soils that drain very quickly, the wider root zone does not necessarily translate into better water access, because the entire profile dries out fast. In such soils, a deep vertical planting that reaches moister subsoil may actually perform better. You need to know your soil type before deciding.
4. Higher Yields in Long Growing Seasons
Stronger roots and better nutrient access set the stage for more flowers and more fruit. In a growing season that extends well beyond the variety’s days to maturity, the trench method can significantly boost your harvest. The plant uses the extra root mass to support heavier fruit load and longer production periods.
Most tomatoes reach harvestability about sixty days after transplanting. In temperate regions with warm summers, achieving that sixty-day window is straightforward. You transplant in mid-May, and by mid-July you have ripe fruit. But the season does not end there. It continues through August and into September. That extra time allows the sideways-planted tomato to fully exploit its larger root system. The plant can continue flowering and setting fruit long after a vertically planted tomato has exhausted its nutrient reserves.
Commercial growers in California’s Central Valley have used variations of this method for decades. They know that the extra root mass translates directly into more pounds of fruit per plant. One study conducted at the University of California, Davis, found that tomato plants with extensive adventitious root systems produced an average of 18 percent more marketable fruit than plants with minimal adventitious roots, all other factors being equal. That is a substantial gain for a simple change in planting technique.
You may also enjoy reading: 7 Tips to Get Biggest Sweet Potato Crop.
The key variable is season length. If your growing season gives you at least two to three weeks beyond the variety’s days to maturity, the trench method likely pays off. If your season is tight — if you live in a short-summer region like the northern Rockies or high-altitude areas — the same strategy may backfire, as I discuss below.
5. Better Utilization of Warm Surface Soil for Early Growth
This fifth reason ties together all the others. The warm surface layer of soil is a limited resource. It disappears quickly as you dig deeper. When you bury tomato sideways, you maximize the amount of stem that contacts this warm, biologically active zone. The result is faster root emergence, faster nutrient cycling by soil microbes, and faster early growth that shortens the time to first flower.
The top six inches of soil contain the majority of organic matter and microbial life in most garden soils. Earthworms, beneficial bacteria, and mycorrhizal fungi all thrive in this layer. By laying the stem horizontally, you place it directly in this rich environment. The adventitious roots that emerge there can immediately form symbiotic relationships with mycorrhizae, which help the plant access phosphorus and other immobile nutrients. A deep vertical planting misses this opportunity because the lower stem is surrounded by less biologically active subsoil.
I recall a reader from Vermont who tried the trench method for the first time last year. She had always planted her tomatoes deep and straight. The season there is short — about ninety frost-free days. She was skeptical that sideways planting would work. But she tried it with half her seedlings and kept the other half vertical. The sideways plants flowered nine days earlier on average. That allowed her to harvest a full two weeks earlier, which in a short season is the difference between a good crop and a great one. She is now a convert.
This benefit is especially valuable for gardeners who grow heirloom varieties with longer maturity times. An heirloom like Brandywine can take eighty-five to ninety days from transplant to harvest. If you bury tomato sideways and gain even a few days of earlier growth, you increase the odds of getting ripe fruit before the first fall frost.
How to Properly Bury a Tomato Sideways
The technique is simple, but a few details make the difference between success and disappointment. Start by digging a shallow trench about four to six inches deep and as long as the stem you plan to bury. Remove all the leaves from the lower portion of the stem, leaving only the top cluster of leaves exposed. Lay the leafless stem horizontally in the trench, and gently bend the top of the plant upward so the leaves are above the soil line. Cover the stem with loose soil, firm it gently, and water it in well.
Choose a day when the soil is moist but not waterlogged. Avoid planting into cold, wet soil, because the stem may rot before roots can form. Wait until the soil temperature at four inches deep reaches at least 60 degrees Fahrenheit (15 degrees Celsius). You can check this with a simple soil thermometer. Planting into cold soil eliminates many of the advantages of the trench method.
Staking or caging should happen at planting time, not later. If you wait until the plant is established, you risk damaging the new adventitious roots. Drive your stake or place your cage before you cover the stem. That way the root system can develop undisturbed.
When to Choose a Different Method
The trench method is not universally superior. In short-season climates where the growing season barely reaches sixty days, the energy the plant invests in building adventitious roots can delay flowering and fruiting. You may end up with fewer tomatoes, not more. The plant puts energy into root growth at the expense of fruit production. If your season is tight, a deep vertical planting that disturbs the root ball less may give you faster top growth and earlier harvests.
Similarly, if you garden in heavy clay soil that drains slowly, the sideways trench can become a waterlogged channel that encourages stem rot. In such soils, mounding the soil up around the base of a vertically planted stem — a technique called hilling — may work better than laying the stem horizontally. Hilling still triggers adventitious root formation but keeps the stem above the wettest zone.
For gardeners in regions with very hot summers where surface soil temperatures exceed 90 degrees Fahrenheit (32 degrees Celsius), the warm-soil advantage of sideways planting disappears. In those conditions, deep vertical planting places the roots in cooler subsoil, which can actually improve growth during the hottest months. Know your climate and adjust accordingly.
A Final Word on the Trench Method
Deciding whether to bury tomato sideways comes down to one question: how long is your growing season? If you have at least sixty-five to seventy warm days after transplanting, the benefits typically outweigh the risks. If your season is shorter, consider deep vertical planting instead. The experiment in the Epic Gardening test garden showed that each method has its place. The key is matching the method to your conditions, not following a single rule for every garden. With the right choice, you give your tomato plants the best possible start and set yourself up for a season of abundant harvests.
