You break a bud apart over the grinder and something hard rolls out onto the table, about the size of a peppercorn, brown with darker stripes running along it like a tiny tiger. Anyone who bought cannabis in the 1970s knew that shape well. The compressed bricks that came up from Mexico were full of them, and a smoker spent the first ten minutes of any evening picking seeds out with the edge of a record sleeve. Then growers in Northern California worked out how to keep the female plants away from pollen entirely, and the word for the result was Spanish: sinsemilla, without seed. Nearly every jar of good flower sold today is sinsemilla, whether or not anyone says so.

So a seed in a modern jar is news.

The pages that rank for this question are mostly written for growers. They explain pollination, describe hermaphrodite plants and the stresses that cause them, warn that seeds cost potency, and finish with a checklist for keeping the next crop clean. All of that is accurate, and we cover the parts a buyer needs. What none of them do is treat the seed as evidence. A seed has a size and a color, and it sits somewhere particular in the bud. Taken together those say roughly when the plant was pollinated, which says a fair amount about how the farm runs. That is where this page spends its time.

How a seed gets into a bud

Cannabis plants are usually either male or female. The buds we smoke are clusters of unfertilized female flowers, each one a small leafy pod (a calyx, or bract) with a pair of sticky hairs reaching out to catch pollen that, in a well-run garden, never arrives. The plant keeps reaching. It keeps making resin. Sinsemilla growing amounts to keeping the females waiting all season.

When pollen does land, the calyx it reached stops waiting and starts building a seed. The plant redirects some of its effort into that seed, and a heavily pollinated plant can end up with buds that are more seed than flower.

Pollen either comes from outside or the plant makes its own. From outside, it is usually a male that slipped through and opened, which on a small outdoor farm can happen to careful people, or pollen blown in on the wind, which travels a long way on a dry afternoon, so a farm with a hemp field upwind has a problem it did nothing to cause. The other case is stranger. Under stress, or because its genetics lean that way, a female can grow male flowers in among her buds. Growers call the plant a hermaphrodite, or hermie. The pale little pollen sacs that appear directly in the bud late in flowering are known as bananas, or nanners, because that is what they look like up close.

Indoors, the classic trigger is light. A plant in flower expects long nights of perfect darkness, and a leaking door seal or a timer that fails for an evening can be enough to make a sensitive plant start hedging its bets.

Reading the seed

The grow guides skip this part. A seed takes several weeks to mature after pollination, so its condition when you find it records how long it had.

A large, hard seed with a dark, striped shell had most of the flowering season to develop. Pollen reached that plant early, which usually means a male in the field or a neighbor’s pollen drifting in during the first weeks of bloom. These seeds tend to sit deep in the bud, sometimes several to a cola.

A small, pale, soft seed, cream or light green and easily crushed between two fingernails, came late. This is the hermie signature. The plant was a few weeks from harvest when it began making its own pollen, and the seeds never finished. You will find these scattered near the surface of the buds, one here and two there, and they are easy to miss until they crackle.

Then count. One mature seed in an eighth of sun-grown flower says a single stray grain of pollen found one bud, and that is weather. Pale seeds in bud after bud from the same jar say the plant was making pollen of its own, which is a fault in the genetics or the room.

What seeds cost the flower

Seeds carry very little of what you are paying for. The cannabinoids and aromatics live in the resin glands on the outside of the flower (our page on cannabis trichomes explains how fragile they are), and a calyx busy swelling around a seed puts less into making them. Early and heavy pollination shows up as flower that smells quieter than it should and weighs more than it looks, because seeds are dense and they are sold by the gram along with everything else.

The smoke is the other cost. A seed that goes into the grinder ends up as crushed hull and oily kernel in your bowl or paper, and it burns hot and acrid, with a sharp crackle and a smell closer to burnt popcorn than to anything the cultivar intended. Our guide on how to grind cannabis recommends breaking buds by hand first for exactly this reason. Feel each piece as it comes apart and pick out anything hard.

The odd history of feminized seed

Much of the cannabis grown from seed now starts as feminized seed, bred to produce only female plants so a grower never has to hunt for males, and the way breeders make it is by persuading a female plant to grow pollen of her own. The trick is deliberate, controlled hermaphroditism. A breeder who does it well selects for mothers that resist herming under ordinary stress. A breeder who does it carelessly can sell a tendency to herm along with the seed, and the grower finds out weeks into flower. Our guide to cannabis phenotypes covers how keepers are chosen and why so many farms grow from cuttings instead, which sidesteps the question.

On planting the one you found

People do, and sometimes it grows, though a seed from a self-pollinated plant tends to inherit the habit that made it.

Indoor seeds and outdoor seeds

We judge them differently, and we think buyers should too. An outdoor farm, or a greenhouse with its sides open to the valley, is at the mercy of the wind and of whoever is growing hemp three ridges over. Our page on sun-grown cannabis argues that those farms make some of the most interesting flower in California, and an occasional mature seed is part of the price of growing under a real sky. Heritage flower can be seedier still. As our guide to landrace strains describes, traditional farmers saved seed from their best plants every year, so the plants were allowed to meet.

A sealed indoor room has no wind. If a jar of indoor flower is full of pale late seeds, the pollen came from inside the room, and that points at a light leak, or at a plant whose genetics were never steady enough to trust in the first place. We are much less forgiving of that, because a sealed room has no weather to blame.

What to do at the counter

Most shops will not let you open a sealed bag, so the first check usually happens at home. Break two or three buds apart over a white plate before you grind anything. One seed, set it aside and carry on. Several pale seeds across several buds, take the package back with the receipt and say what you found; a good shop wants to hear it, because the same batch is still on their shelf. Our guide on how to read a cannabis COA shows where the batch number lives. Write it down.

Pre-rolls are another matter. Nobody can see a seed inside a cone, and the first sign is a pop and a flare halfway down. One reason, among several, that we buy flower and roll it ourselves.

Our position

A single dark seed in sun-grown flower from a small farm does not bother us, and we would rather have that farm’s flower with the occasional seed than a spotless jar from a room that tastes of nothing. Pale seeds scattered through indoor flower are a different matter. They mean the plant was stressed or badly bred, and the same stress tends to show up elsewhere, in thinner resin and a flatter nose. Sinsemilla was the first real craft standard in American cannabis, decades before anyone wrote the word craft on a label, and our guide on what makes cannabis craft still starts from the same idea: somebody paid attention all season. A seed is where you find out whether they did.

Seeds in Cannabis, Explained