How to tell when marijuana seeds are ready to harvest

Why seed maturity matters

Cannabis seeds that are harvested too early often result in:

Low germination rates
Weak or deformed seedlings
Unstable genetics
Wasted time and effort

By waiting until seeds are fully mature before harvesting, you ensure your next generation of plants starts off with strength and consistency.

How are marijuana seeds produced?

To harvest seeds, you must first intentionally pollinate a female plant with male pollen:

A male plant produces pollen sacs.
A female plant produces pistils and flowers.
When pollinated, the female’s calyxes (bud sites) begin producing seeds instead of resinous flowers.

Seeds typically develop inside the buds over the next 4 to 6 weeks following pollination.

Tip: Isolate pollinated females from other flowering plants to avoid accidental pollination of your main crop.

How long does it take for marijuana seeds to mature?

After pollination, cannabis seeds need at least 4 weeks to develop, with full maturity typically occurring at 6 weeks.

Time After Pollination
Seed Stage
Week 1–2 – Pollen fertilises calyx
Week 3–4 – Embryo formation begins
Week 5–6+ – Seed coat hardens, full maturity develops

How to tell when marijuana seeds are ready to harvest

1. Visual signs of maturity

Fully mature marijuana seeds show distinct physical traits:

Trait – Description
Colour – Dark brown, grey, or black with tiger stripes
Size – Slightly larger and rounder than immature seeds
Texture – Hard outer shell, smooth to the touch
Sheen – Slightly glossy surface (vs dull in young seeds)
Pattern – Visible mottling or marbling

Immature seeds:

Pale green, tan, or white
Soft shells
Easily crushed
No patterns or striping

2. Seeds easily separate from calyx

When mature, the seeds loosen naturally from the calyx. Gently pinch the bud—if the seeds fall out or pop out with minimal pressure, they’re likely ready.

If you have to force the seed out, it may not be mature yet.

3. Drying fan leaves and calyx browning

On the seeded branches:

Sugar leaves turn yellow and dry out
Calyxes turn brown or amber and shrink slightly
Pistils recede or fall off

These signs indicate the plant is finishing its seed cycle and is ready for harvest.

4. Germination test (optional)

If unsure, take one or two seeds and perform a quick germination test using the paper towel method. If they sprout within 48 to 72 hours, your seeds are mature.

How to harvest marijuana seeds

Once seeds are mature:

Cut down the seeded branches
Hang or lay them out to dry in a dark, well-ventilated space (16–21°C, 50–60% humidity)
Dry for 7 to 10 days, until stems snap and buds are brittle
Gently break apart the buds by hand to release the seeds
Use a tray and screen to separate seeds from plant matter

Tip: Use gloves—mature seeds are sharp and resinous buds can be sticky.

How to dry and cure cannabis seeds

Why dry seeds?

Freshly harvested seeds contain moisture that can lead to:

Mould
Spoilage
Failed germination during storage

Drying method

Spread seeds in a single layer on parchment or cardboard
Store in a dark, dry room (16–21°C)
Allow to air dry for 5 to 7 more days
Shake seeds gently—if they sound hard and rattle, they’re dry

How to store marijuana seeds for future grows

Best practices

Use airtight containers (glass jars or seed tubes)
Add a silica packet to control moisture
Label with strain, harvest date, and generation
Store in a dark, cool place (fridge or drawer)

Avoid

Heat
Light
Humidity
Frequent temperature changes

Properly stored seeds can remain viable for three to five+ years.

What to do with immature seeds

Sometimes, a few underdeveloped seeds may appear during harvest.

You can:

Test a small batch with a germination trial
Allow to cure longer and retry
Compost or discard them if they're clearly pale, soft, or cracked

Don’t store or plant seeds that crush easily or appear green or white. They’re unlikely to sprout and may carry weak genetics.

Can you harvest seeds and buds at the same time?

Yes—but only if you’re growing for seed production, not resin quality.

Pollinated plants focus energy on seed formation, not trichome development. As a result:

THC levels are lower
Bud density decreases
Overall flower quality is reduced

That’s why seed production and flower production are separate goals. Professional breeders often dedicate specific plants solely for seed harvesting while preserving other females for bud production.

Tips for successful cannabis seed production

Use healthy parent plants from proven genetics like Mavericks Genetics
Grow in controlled environments to avoid accidental pollination
Keep detailed notes: strain, generation (F1, F2, etc.), traits, and parent line
Label and date all harvested seeds
Allow 6 to 8 full weeks from pollination to harvest
Use feminised pollen if you want all-female offspring

Common mistakes when harvesting marijuana seeds

Mistake – What happens – How to avoid
Harvesting too early – Soft, immature seeds that won’t germinate – Wait until seeds darken and loosen
Not drying seeds before storing – Mould or rot during storage – Always air-dry seeds for 5 to 7 days
Storing seeds in light or heat – Germination rates drop quickly – Use dark, cool storage
Not isolating pollinated plants – Entire grow becomes seeded – Use separate grow space or tent

Final thoughts: Timing is everything when harvesting marijuana seeds

Knowing when your marijuana seeds are ready to harvest is all about observing the visual cues, timing the pollination cycle, and handling the seeds with care. Mature seeds are darker, harder, and separate easily from the plant. Rushing the process can leave you with weak or unusable genetics.

Whether you're a hobby breeder or preserving elite lines from Mavericks Genetics, harvesting at the right time ensures your seeds will germinate strong and grow with full potential.

Looking to breed your own cannabis?

Get started with premium, feminised marijuana seeds from Mavericks Genetics. Our genetics are stable, high-yielding, and perfect for both flower and seed production.