Beginner Guide: How Deep Should You Plant Seeds?
Planting seeds sounds simple, but one small detail makes a huge difference in whether your seeds sprout or fail: depth. Many beginners either plant seeds too deep, where they can’t reach the surface, or too shallow, where they dry out or get dislodged.
Here’s the clear, easy-to-follow rule for seed depth and how to get strong germination every time.
The simple depth rule for beginners
Seed depth is based on seed size.
Here’s the universal guideline:
Plant seeds at a depth equal to 2–3 times their diameter.
That means:
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Small herb seeds like basil or oregano: surface-sow or barely cover
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Medium seeds like tomatoes: about 1/8 to 1/4 inch deep
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Large seeds like cucumbers, beans, or peas: 1 to 1.5 inches deep
Planting deeper than that can reduce germination or cause weak seedlings.
Why seed depth matters
1. Too deep = seed can’t reach the surface
Seeds use stored energy to push upward. If planted too deep, they run out of energy and die underground.
2. Too shallow = seed dries out or is exposed
This is especially true indoors, where air is dry and containers are small.
3. Wrong depth = delayed or uneven germination
You might think your seeds are bad when the real issue is depth.
Getting this right is one of the fastest ways to improve seed-starting success.
Examples: common garden seeds
Basil, oregano, and other tiny herbs
Plant: Surface or a dusting of soil
Why: Light helps these seeds germinate
Tomatoes and peppers
Plant: 1/8 to 1/4 inch deep
Why: They need coverage but still close to light and warmth
Cucumbers, beans, peas, squash
Plant: 1 to 1.5 inches deep
Why: Larger seeds contain more energy and can push through more soil
How to measure depth without guessing
A simple trick:
Use the side of a pencil or your fingertip.
Or, if you use seed sticks like Push N’Grow, the depth measurement is already set for you — no measuring needed.
(When Blog #6 is live, we’ll link to How Push N’Grow Ensures Correct Seed Depth.)
Why some seeds prefer light
A few seeds should not be buried at all:
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Basil
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Oregano
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Lettuce
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Some flowers
These seeds need light to trigger germination, so burying them harms their chances.
When seeds still don’t sprout, depth may not be the only issue
Sometimes the problem isn’t depth but:
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low temperature
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dry soil
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old seeds
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compacted soil mix
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poor light
(This is where you’ll later link to Why Seeds Don’t Sprout — another blog in the series.)
Seed depth is simple once you understand it
Beginners often worry too much about exact measurements. But once you learn the basic depth rule and understand why depth matters, planting becomes far more predictable.
When in doubt:
Shallow is safer than deep.
And if you use depth-guided tools like Push N’Grow Seed Sticks, the guesswork is removed entirely.