How Deep To Plant Tomato Transplants | Bury the Stem Deep

A common mistake with tomato transplants is treating them like any other vegetable seedling. Most garden plants need the crown to sit at soil level, but tomatoes flip that rule. Burying the stem isn’t an accident — it’s the main trick to strong plants.

Gardeners consistently recommend planting two-thirds to three-quarters of the stem underground, using either a deep hole or a shallow trench. This article walks through both methods so you can pick the approach that fits your garden and your transplants.

The Standard Deep Planting Recommendation

When you move a tomato transplant from its nursery pot to the garden, you are not limited to the depth of the root ball. The stem itself can produce roots if it stays in contact with moist soil. That is the core reason for planting deep.

Most gardening sources advise burying the root ball plus several sets of lower leaves. The remaining top few inches of stem and leaves should stick out above the ground. This method works for in-ground beds, raised beds, and large containers.

The buried stem develops adventitious roots — roots that form along the stem rather than from the original root ball. A larger root system means better water and nutrient uptake, which supports stronger growth and heavier fruiting.

Why Gardeners Often Plant Too Shallow

Many gardeners follow the same planting depth for every seedling: just deep enough to cover the root ball. That instinct comes from standard transplanting rules for peppers, lettuce, or cucumbers. Tomatoes break that pattern completely.

If you plant a tomato at the same depth it grew in the cell pack, you leave a long, bare stem above ground. That stem could be producing roots instead. Shallow planting also makes the plant top-heavy, increasing the chance of lodging — falling over under the weight of fruit or wind.

• Familiarity with other vegetables: Most garden guides say plant at the same depth as the pot, so tomatoes feel like an exception.
• Fear of rotting the stem: Some worry that burying the stem will cause rot, though healthy tomato stems root readily in moist soil.
• Not knowing leggy plants can be saved: Long, spindly seedlings are actually easier to plant deep using the trench method.
• Underestimating root potential: The stem can grow an entirely new root system, not just a few extra hairs.

Once you understand that tomatoes root along the stem, shallow planting stops making sense. The stem wants to be underground.

Two Proven Methods: Deep Hole vs Trench

Two main techniques get the job done: the deep-hole method and the trench method. Both bury the stem, but they work best in different situations. The common recommendation from gardening sources, such as Bonnieplants’ guide to bury two-thirds to three-quarters of the stem, is a reliable starting point.

The deep-hole method requires digging a hole deep enough to sink the root ball and most of the stem, leaving only a few inches of leaves above ground. You can mix a small amount of balanced fertilizer, like 5-10-5, into the bottom of the hole before planting. This method works well in loose, well-amended soil.

The trench method is better for compact soil or for leggy transplants. Instead of a deep hole, dig a trench about 5 or 6 inches deep. Lay the plant on its side, gently curving the top upward so the leaves stick out. The stem naturally turns toward the sun while roots develop along the buried portion.

Whichever method you choose, the buried stem will produce roots. The key is to ensure the soil stays consistently moist for the first two weeks after planting while those roots form.

Step-by-Step Guide to Deep Planting

Follow these steps to give your tomato transplants the best start. The process takes about the same time as shallow planting, but the payoff comes later in the season.

1. Pinch off the lower leaves. Remove the leaves that will be underground. Leave the top cluster of leaves intact. Snip with scissors or pinch with your nails — either way works.
2. Dig the hole or trench. For the deep-hole method, dig a hole 6 to 10 inches deep. For the trench method, dig a trench 5 to 6 inches deep and long enough to accommodate the stem horizontally.
3. Place the transplant. Lower the root ball into the hole or lay the plant sideways in the trench. Gently curve the stem so the top leaves face upward. Do not bend sharply.
4. Backfill and water. Fill in with soil, pressing lightly around the stem to remove air pockets. Water thoroughly with a gentle stream to settle the soil around the buried stem.

Water deeply every few days for the first two weeks if there is no rain. Once the new roots establish, the plant becomes more drought-tolerant, but consistent watering early on is critical.

What Happens Below the Soil?

Within days of planting, small bumps appear along the buried stem. These are root primordia — the start of adventitious roots. They grow quickly in warm, moist soil. The deep-hole method, explained in detail by gardening expert Margaret Roach in her deep-hole method bury stem technique, ensures the buried stem produces a full second root system.

That larger root mass anchors the plant and forages for water and nutrients more effectively. Some gardeners note that deep planting can put roots in slightly cooler soil, which may slow early growth in northern climates, but the trade-off is a much sturdier plant overall.

The buried leaves decompose underground, adding organic matter that supports the developing roots. This process is natural and does not cause disease if the leaves pinched off are healthy. Avoid burying leaves with spots or mildew.

The Bottom Line

Tomatoes are unique among common garden vegetables because their stems can grow roots. Planting two-thirds to three-quarters of the stem underground, either with a deep hole or a shallow trench, gives the plant a much larger root system. This reduces the chance of lodging and supports stronger growth and better fruit production.

If your transplants are leggy, use the trench method. If your soil is loose, dig a deep hole. Either way, the stem will root, and your plants will likely outperform those planted at standard depth. For specific advice on soil temperature or variety considerations, your local extension service or an experienced gardening neighbor can offer guidance tailored to your climate.