Cannabis Seed Quality: What To Know Before You Grow

Quality seeds are the key to healthy plants and good harvests. While proper feeding/watering and good light quality obviously also affect the health and yield potential of your plants, starting a grow with top-shelf genetics is equally, if not more important. But how exactly do you tell quality cannabis seeds apart from the rest? In this article, we’ll show you exactly how to spot top-quality cannabis seeds, avoid duds, and start your grow off right. 

Appearance And Feel - Checking The Colour, Size, and Shape Of Your Seeds

Unlike other agricultural crops (like vegetables, fruit, or grain), cannabis hasn’t undergone the vigorous breeding techniques that ensure a stable crop. This means that you’ll sometimes sow a pack of seeds technically labeled as the same “strain,” but may end up with very different looking plants. It also means that the individual seeds you buy from a seed bank can vary in appearance.

The fact that cannabis seeds can vary in appearance has led some growers to think that the size, shape, or colour of a seed dictates its quality.

We do not recommend taking the size or shape of a seed into consideration as a sign of its quality. Some strains simply produce smaller seeds than others, and sometimes the same plant can produce seeds of different sizes and shapes. Never discard a seed just because it is smaller or of a different shape than another one.

The colour and feel of a seed, on the other hand, can tell you a little more about its maturity and, potential to germinate or grow into a healthy seedling.

Mature cannabis seeds usually have a hard outer shell that can vary in colour from very dark (or almost black) to very light grey and may have tiger-like stripes. You should be able to firmly press these seeds between your fingers without damaging them.

Immature cannabis seeds, on the other hand, tend to be green and have a soft outer shell that breaks when any kind of pressure is applied to it.

Keep in mind that the simple process of packaging and storing cannabis seeds can also affect their appearance. Abrupt changes in humidity, temperature, or light exposure can make some seeds appear darker or lighter than others, but ultimately have no effect on their quality.

Remember, just like animals and other living things, cannabis seeds are biologically different from one another (even if they are technically the same strain) and therefore will exhibit different physical characteristics. Don’t let these natural differences fool you into thinking that a larger, rounder, and darker seed (for example) is of better quality than a lighter, smaller, and more oval-shaped one.

The appearance of F1 Hybrid Cannabis Seeds

F1 hybrid seeds can exhibit a distinct appearance in comparison to traditional strains. When you receive a packet of F1 hybrid seeds, you may observe sometimes that the seeds may look small, slightly open or cracked. Rest assured, this is entirely normal.

F1 hybrid seeds are produced from two inbred lines that have undergone several generations of self-pollination. Therefore, inbred lines are prone to suffer inbreeding depression, which can lead to reduced seed production and occasional yield of small, open seeds. Nevertheless, when these seeds are germinated, they demonstrate exceptional germination rates and give rise to robust, thriving plants.

Can You Tell The Sex Of Cannabis Seeds From Their Appearance?

We hear this question all the time from clients and beginner growers, and the answer is a resounding no. There is simply no way to tell the sex of a cannabis seed just by looking at it.

A quick web search will bring up all kinds of myths about how to tell female cannabis seeds from males. One of the most popular ones comes from a chart showing 5 different seeds that claims that the female seeds have “a perfectly round volcano-like depression at the bottom (from where the seed was attached to the plant).”

This is absolutely not true. As we explained earlier, cannabis seeds naturally look different, and no single physical trait of a seed can tell you whether that seed contains the genetics for a male or female plant. The only way to tell a female cannabis plant from a male is by looking at its flowers when it begins to sex. Don’t be fooled into throwing out perfectly healthy seeds just because a popular internet chart told you so.

Growing Seeds From A Bag (Bagseed)

Some smokers might be pleased to see some cannabis seeds in their bag, and might think themselves lucky. However, finding seeds in a bag is bad for various reasons. For one, this means the grower has messed up and allowed their female plants to be pollinated by an invading male. When flowers are pollinated, they stop producing THC-containing resin and divert their energy toward producing seeds. Secondly, the seeds will have added to the overall weight of the bag, which means less weed for your buck. Finally, when germinating this seed, there is a chance of it being male due to uncertain pollen origin from either a male plant or a stressed female plant producing pollen. 

With this said, you may get lucky if the strain they were growing really is prime. In this case, it’s worth carrying out the following test to see if it’s worth germinating.

Germinating All Your Seeds Regardless

The one true method to test the genetic potential of a seed is to simply put it in the soil. It won’t take too long to see the results. This option is best for the hobby home grower who has time and space to spare for a risky project. Growers cultivating cannabis for commercial use likely don’t have the excess time to invest.

Source Your Seeds Well

A solid way to obtain great seeds is to find a reputable seed bank. These companies pride themselves of their breeding skills and make sure that their customers receive exactly what has been advertised. They have reputations to cater to, so delivering anything less would only harm their image.

The alternative to this is to risk buying seeds from a hobbyist. This isn’t to say that hobby growers cannot produce fantastic genetics, but if you don’t know them or their skills, there’s no way to know whether your seeds will grow.

Conducting The Float Test

If you are still unsure about the quality of your seeds after analysing their appearance and toughness, it’s time to put your lab coat and goggles on. Well, not quite. This test is extremely easy and only has two possible outcomes. Fill up a drinking glass or glass jar with water (preferably spring or distilled) and place your seeds on the surface.

This simple and cost-effective method is a great way to tell the good genetics from the bad; they will sink or swim, literally. Seeds that remain buoyant on the surface are more than likely of poor quality and are to be discarded. Seeds that sink to the bottom like a botanical cannonball are probably healthy and should be germinated.

However, slight patience is required when conducting the float test, as results are not immediately apparent. You'll have to wait for approximately 1–2 hours before confirming the results. Some good-quality seeds will need adequate time to absorb enough water for them to sink. Use this time to go water the garden and get some much needed pruning done. Upon your return, any seeds that remain on the surface are most likely not viable and won't be worth further time and effort.

It's important to only conduct this test if you are planning to germinate the seeds immediately afterwards. The viable seeds that sunk to the bottom of the glass will have taken in water, crossing the membrane of the seed and signalling that it's time to come to life—activating germination.

Cannabis Seed Quality - The Bottom Line

The quality of your seeds has a direct impact on the quality of your harvest. With that in mind, you should make sure to use the tips above to test the quality of any seeds you buy. All that being said, though, be sure to remember that each cannabis plant is different and, therefore, is going to produce slightly different seeds.