Which way up do I plant a germinated seed?

Q: Which way up do I plant a germinated seed?

Plant a germinated cannabis seed taproot (radicle) pointing down, 0.5–1.5 cm (¼–½ in) deep, in moist, light mix. Move it once the taproot is about 0.5–2 cm long, before it gets long and brittle. If you get it wrong, don't dig it up: the root turns down by itself. Handling and breaking the taproot does more harm than planting it sideways.

Short answer

Plant a germinated cannabis seed taproot down, 0.5–1.5 cm (¼–½ in) deep, ideally when the taproot is 0.5–2 cm long. If it went in sideways or upside down, leave it: the root turns down on its own. Grower practice.

Why

The taproot (radicle) responds to gravity and grows down; the shoot grows up. A seed set the wrong way spends a little energy turning round, then carries on.

The real risk is handling. A long taproot is brittle and easily snapped when lifted from a towel, which is why lab protocols germinate seeds in a tube and transfer them early ^[1].

Depth matters more than orientation. Too deep and the seedling spends its reserves climbing; too shallow and it dries out or emerges with the shell stuck on.

Warmth gets it up fast. Keep the medium around 22–27 °C (72–81 °F); hemp germination slows sharply in the cold ^[2].

The numbers

Item	Target
Orientation	Taproot down; sideways is fine
Planting depth	0.5–1.5 cm (¼–½ in)
Taproot length at planting	0.5–2 cm (¼–¾ in)
Medium temperature	22–27 °C (72–81 °F)
Time to surface	Usually 1–3 days after planting

What to do

Pre-moisten a light seedling mix or plug so it holds together but doesn't drip.
Make a hole 0.5–1.5 cm deep with a pencil.
Lift the seed by the shell, not the root, with clean tweezers.
Drop it in taproot down, cover loosely, firm very lightly.
Keep it warm and just moist; don't flood it ^[3].

Common mistakes

Digging the seed up to check on it.
Leaving the taproot in the towel until it is 5 cm long.
Planting 3 cm deep "to be safe".
Watering a fresh plant so hard the seed washes out.

Full article: Germination methods compared
What if the seed shell is stuck? · Why won't my seeds germinate?
Terms: taproot · radicle

Follow-up questions

What if I planted my seed upside down?

Leave it. A cannabis seed planted upside down or sideways usually corrects itself, because the taproot grows downward with gravity and the shoot grows up. It may surface a day or so later and with a slight bend in the stem. Digging it up to turn it risks snapping the fragile taproot, which does far more damage than the wrong orientation.

How long should the taproot be before planting?

Plant a cannabis seed from a paper towel once the taproot is about 0.5–2 cm (¼–¾ in) long. Shorter is fine; longer taproots are brittle, may grow root hairs into the towel and break when you lift them. If one has grown long, lay it in a pre-made hole with the root pointing down and cover it gently rather than forcing it straight.

Should the seed be covered completely?

Yes. Cover a germinated cannabis seed completely with 0.5–1.5 cm (¼–½ in) of light, moist mix, and firm it very lightly. A seed left on the surface can dry out, and a shallow seed often comes up with its shell still stuck on the leaves. Planting much deeper than about 1.5 cm wastes the seed's reserves on a long climb to the light.

Sources

Sorokin A, Yadav NS, Gaudet D, Kovalchuk I, 2021. Development and standardization of rapid and efficient seed germination protocol for Cannabis sativa. Bio-protocol 11(1): e3875. doi.org/10.21769/BioProtoc.3875

Geneve RL, et al., 2022. Temperature limits for seed germination in industrial hemp (Cannabis sativa L.). Crops 2(4):415–427. doi.org/10.3390/crops2040029

University of Minnesota Extension. How to prevent seedling damping off. extension.umn.edu/solve-problem/how-prevent-seedling-damping