So, How Deep to Plant Tomatoes?

Every gardener knows, or soon learns, that the makings of a great harvest are quite literally sown all the way back at the beginning of the season with planting.

tomato plant in cage
tomato plant inside a DIY tomato cage made from wood branches

Planting may never be handled haphazardly if you want your plans to grow quickly, grow big and thrive. Every plant has its own requirements, and learning what they are is essential.

To help in that regard will be looking at tomatoes today. So, how deep should you plant tomatoes?

Tomato seeds should be planted about a quarter of an inch deep, however, tomato seedlings do benefit from being planted deeper with more of the stem underground, potentially 6 inches deep or more.

Growing tomatoes is fascinating especially when it comes to planting depth. The seeds will struggle to germinate and develop if they are planted too deep, but you want to plant the seedlings deeper if you can.

If more of the stem is beneath the surface of the soil, it will actually develop a larger and stronger root system to support the rest of the plant and the fruit!

Interesting stuff, and if you want a bumper crop you might want to replant your seedlings deeper when the time comes. There’s lots more to learn, let’s get to it…

How Deep Should You Plant Tomatoes in Pots?

If you are potting tomatoes, you will want to follow the advice above to the letter: a quarter-inch for seeds and up to 6 inches for seedlings, maybe more if they are a big variety.

As always, when choosing a pot that is going to be a permanent home for your tomatoes you must ensure it is wide enough, deep enough, and can afford enough support (stakes, trellis) for the developing plant.

They will get top-heavy, so try to pick a pot that will prevent toppling or root binding. 10×12 inches is a good standard for medium-sized varieties.

How Deep Should You Plant Tomatoes in Other Containers?

Whatever other containers you are using, the rules still apply. A quarter of an inch for seeds and up to 6 inches deep or more for seedlings.

How Deep Should You Plant Tomatoes in a Grow Bag?

Tomatoes can do alright in a grow bag, but support might quickly become an issue. Whatever your reasons for using a grow bag, necessity or preference, stick with a quarter of an inch deep for the seeds and up to six inches for the seedlings, same as always.

How Deep Should You Plant Tomatoes in a Raised Bed?

Tomatoes can do wonderfully in a raised bed, though this can make them a bit more vulnerable to wind and also to late afternoon sun by increasing their overall height.

Even so, you know the rule by now: a quarter of an inch for seeds and up to 6 inches or more for seedlings.

Also, do keep in mind that if you are planting them in a raised bed that you should leave a gap between the surface of the soil in the bed, and the rim of the bed itself.

This is to prevent soil from washing away when watering, and also to give yourself some room to cover the surface with mulch or other coverings.

That can help to shelter your seeds and also retain moisture, a benefit to your young and mature plants alike.

Why Do You Plant Tomato Seedlings Deeper than Seeds?

There is a great reason why you should plant your seedlings and young plants deeper than the root ball might suggest.

This is because tomato plants will actually grow more roots along any part of the stem that is surrounded by soil. You can see where this is going!

By planting the seedlings deeper than “needed” you will basically supercharge their root systems, which will in turn make them more robust and able to produce a much larger harvest.

A tomato plant with an extensive root system will always be healthier and happier than one with a scrawny root ball.

Aside from better fruit, your plants will better withstand stress, diseases and pests, too. It is a can’t-lose proposition.

Deeper planting of developed plants is always recommended if you want the best results, but there is a trick to it.

You must carefully snip or pinch off any leaves along the stem that would be underground, and do it all without unduly injuring the young plant or its delicate roots. This takes a steady hand and practice, but it is so worth it.

What Happens if You Plant Tomatoes Too Deeply?

Seeds that are planted too deeply will fail to germinate or, if they do, develop more slowly, most times. If tomato seedlings are planted too deeply, they may rot or develop other fungal diseases, especially if leaves are left underground.

It’s essential to ensure that the seedlings are planted up to their first set of exposed leaves and not deeper to avoid these problems.

What Happens if Tomatoes are Planted Too Shallow?

Just the opposite. Seeds will fail to germinate, perish from exposure or be picked off by birds or other animals. Seedlings might struggle to stabilize, but they can be okay if a little shallow.

Are there Any Guidelines for Planting Depth in Different Soils?

Not really, but if your soil composition is sub-optimal, hedge your bets on seedlings, and don’t plant them quite as deep as you might otherwise to ensure maximum growth.

How Deep Should You Plant Transplanted Tomatoes?

Transplanted tomato plants should be planted deeply as with seedlings above. 6 inches or more for true seedlings, or about as deep as the root ball is wide for larger plants.

Keep in mind that larger plants will be significantly riskier to transplant compared to small ones.

No plant likes having its roots disturbed, and while tomatoes are somewhat more tolerant, you should think twice before you commit on larger, mature tomato plants.

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