How Deep to Plant Tomato Seedlings?

As a gardener remember this, a lush top can be achieved only with good root system down there.

A healthy plant includes stronger root system and attractive green foliage. Same goes with tomato plants.

Most gardening gurus recommend planting tomatoes in deep soil and this tip will benefit you with quality yield.

Why? What’s the science behind this?

Roots can be formed all along the buried portion of tomato plant stem. This is called as adventitious roots, in simple words – plants like tomatoes can form roots on upper part of the plant including stem when you bury them in soil.

Apart from firmness, more roots increase nutrients uptake from soil, resulting in healthier plant with bountiful of yield.

So, how deep to plant or replant tomato seedlings for better harvest?

To make most of adventitious roots of tomatoes, you must plant 2/3rd (two-thirds) size of your tomato plant. This includes main root ball and stem.

Depth of the plant hole can be determined based on the height of the tomato seedling.

If you’re very much interested in root system of tomatoes, read below lines. Else, you can jump to the core topic.

Understanding Tomato Plant Roots

Plant gets its nutrients from soil through roots. They are warehouses of plants and actively work to anchor, absorb minerals and water, and store food reserves.

Amateur gardeners often worry about healthy foliage and stem, but fail to check stronger root system. As mentioned earlier, green foliage with fruits can be achieved only with excellent root system.

Depending on how you started growing the tomato plant, they can develop taproot or fibrous root system. Plants grown from seed will have taproot system and when you grow tomatoes from cuttings then fibrous root system can be exhibited. (Source)

Tomatoes with taproot system will need deep well-drained soil. In case, if you’re planning to replant tomatoes that are grown from seeds, then you must consider taller container.

Taproot system has one long root that penetrates deeper into the soil to uptake needed nutrients and water.

How deep do tomato plant roots grow?

In extreme cases, taproot can go up-to 3 feet. This happens when soil is loose but has low nutrients and less water.

In common conditions, a healthy tomato plant root will extend to 2 feet. However, the main root system can be found in first 12 inches.

You can see small roots coming out of the long taproot.

To encourage the growth of root system, gardeners are recommended to transplant tomato plant into several small containers before shifting it to garden.

Check this out: Tomato Branches Curling Down

Why to plant tomato seedlings deeply?

Every time you transplant a plant, it is recommended to repot in a slightly larger container.

In tomatoes case, you must dig deeper hole to bury some parts of the stem.

As mentioned above, tomatoes have interesting roots that can be grown on stems when they are buried in soil.

This will increase lateral roots. While the long taproot gets nutrients & water from depth, lateral roots also benefit the plant to absorb fertilizers and moisture from surface of the soil.

Planting tomatoes deeply will result in strong roots that help to withstand strong winds.

This is what Lucy Heyming (certified gardening master in Riverside) tells, dig and then dig some more when it comes to tomatoes.

How Deep to Plant Tomato Seedlings?

Measure the plant size.

Dig a hole that is 2/3rd deep of your tomato seedling height.

Choose the seedling that is healthy and strong enough to survive the transplant shock.

When should I repot tomato seedlings?

It’s best to repot when the seedling is at-least 3-4 inches tall with true leaves. You might heard people saying to repot only when the seedlings are 6 to 10 inches. Yes, this is true.

These 10 inches tall tomato seedlings will be healthy enough to survive the change in temperature, water and soil.

There are cases where you get leggy tomato seedlings. Later in this article, I’ll give you a small tip on how deep to replant leggy seedlings.

Also Read: When Is It Too Late to Plant Tomatoes?

Step: 1 Prepare the soil

Make it easy for the roots to easily penetrate into deep soil.

Compacted soil won’t allow new plant roots to penetrate.

Loose soil does the work.

Add compost, perlite and garden soil that drain the water well.

Conduct soil pH test, tomatoes prefer 6 – 6.8 (Source)

If you’re growing in container, then choose bigger container so that the seedling can be planted in depth.

Even in raised beds you must ensure the height of the raised bed must be more than height to your tomato seedlings, because after loose soil the root system can’t penetrate into the hard soil under raised beds.

Step: 2 Dig a hole

How deep?

For normal deep hole method of planting, the depth should be 2-3rd of the tomato seedling height. You should also include stem and root ball.

You can remove lower leaves of the plant, but make sure not to snap stem.

Be gentle while repotting the plant.

Loosen the roots and place the seedling into the hole. Some experts recommend adding dry banana peel or Epsom salt to boost plant growth. Fill it with loose soil covering most parts of the stem.

Second method of planting is for leggy tomato seedlings

Trench method comes as a saver for leggy tomato seedlings.

Prepare your raised bed with loose soil mixed with compost and required nutritional elements.

  • Dig 6 inches deep and 2/3rd wide of the tomato seedling.
  • Put the seedling sideways horizontally.
  • Cover with soil including the lower leaves of the tomato seedling.
  • Slightly make the top part facing upwards by supporting the seedling with small stone or soil.
  • With good sun exposure the plant grow vertically.

Check out this video on how to plant leggy seedling in raised bed.

Step: 3 Transplant tomato seedling

After digging hole of about 2/3rd of seedling, you can drop dry banana peels, Epsom salt or powered eggshells to the planting hole.

These ingredients will slowly release the nutrients to soil and ensure the plant gets required minerals as it grows.

Fill the hole with loose soil till the lower leaves of tomato seedling.

This will eventually help the stem to pop-out new roots to uptake water and nutrients.

Step: 4 Trellis support

To save your tomato plant from wind, it’s recommended to give support of a wooden stick or cage.

Though seedling doesn’t need support for now, when the plant grows up-to certain height trellis or wooden stick will help them to stay strong.

Else, the plant bends due to heavy fruits resulting in end rot.

Also Read: What is Best Mulch for Tomatoes in Containers?

Step: 5 Watering

The way you water will impact the growth.

Slow and generous watering will allow the root system to develop. This is when you will get benefit by deep planting.

Instead of watering on leaves, use hose to water at the base of the plant.

Watering frequency and the quality of water will help to boost the plant growth.

Also Read: Should I Cut Off Yellow Leaves on Tomato Plants?

Step: 6 Sunlight

Tomato plant need 6-8 hours of direct sunlight.

Water and sunlight are essential for photosynthesis process.

Place the plant pot or arrange the raised bed where the seedling can get ample amount of sunlight.

In harsh summer, you can use shade cloth to save the plant leaves from getting sunburned.

Check this out: How Long Can a Tomato Plant Go Without Water?

Step: 7 Fertilizing

Tomatoes are heavy feeders.

This is why they are planted deep, so that it gets all the required nutrients beneath the soil.

As you already added compost while planting the seedling, wait for few weeks so that plant starts growing new leaves.

Fertilize your tomato plant as it starts growing flowers.

Adding natural fertilizers like bone meal, wood ash and banana peels will help the plant to thrive.

Important tips to grow tomato seedlings

Overwatering is common problem faced by new gardeners. This will result in root rot and the leaves of the tomato plant turns yellow.

If not rescued, the plant will eventually die.

Water the tomato seedling twice if you’re living in tropical or sub tropical regions.

According to the climate, regulate the watering frequency.

Underwatering will not allow roots to go deep and the plant will not benefit by deep planting.

Not getting enough sunlight will negatively impact the plant growth and yield.

Soil is very crucial for growing seedling, it must be well-drained, included natural fertilizers and slightly acidic.

Choosing wrong growing medium will result in overwatering or stunted plant growth.


How deep you plant the tomato seedling will impact the yield.

When 2/3rd part of the plant is under the soil, it develops more roots around the stem.

More roots means more nutrient and water uptake.

As the plant gets abundant amount of food in form of water, sunlight and minerals, the plant produces more blossoms and result in quality juicy fruit.

Plant seedling in a deep hole that is 2/3rd height of the plant, also cover the base of plant with potting soil.

Did you ever plant tomato seedling sideways? Share your experience in comments.

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