Cannabis Seed Germination — Troubleshooting Guide

Unless you are using cuttings, growing weed starts with germinating your seeds. If your seeds don’t sprout, for whatever reason, your grow will be over before it even has a chance to start. But If you know the reasons behind germination problems, your chances of getting your grow off to a great start will greatly increase!

WHY YOUR CANNABIS SEEDS AREN’T GERMINATING

There are a whole lot of things that can prevent cannabis seeds from germinating. Here are some of the most common reasons why your seeds may not “pop”:

1. BAD SEEDS

Got a bag of “mystery seeds” from your local source or “bargain seeds” from an unknown vendor off the internet? If so, chances are they won’t germinate. Reputable seed banks like Royal Queen Seeds will always test their seeds for quality and germination rate.

To get your grow off to a great start, sourcing quality cannabis seeds is the best thing you can do. Not only will your germination rates be better, but your plants will also grow healthier with better yields at harvest time.

2. IMPROPER STORAGE

Just like food, seeds are living organisms that need to be stored properly, otherwise they'll degrade, die, or won’t germinate. When storing your seeds, keep them away from light, extreme temperatures, and humidity. A dark cupboard with stable temperatures is fine. For long-term storage, place seeds in a sealed container and store them in the fridge.

For more information on storing your cannabis seeds properly, see our blog on How To Preserve Seeds.

3. HANDLING SEEDS WITH BARE HANDS

Handling your cannabis seeds with bare hands can contaminate them with all kinds of nasties like bacteria and fungus. Unfortunately, seeds and seedlings are especially vulnerable to these types of harmful pathogens.

To prevent spoiling your seeds, avoid unnecessary handling. Use clean gloves and some disinfected tweezers or something similar. This will greatly minimise the risk of your seeds being contaminated.

4. SEEDS BURIED TOO SHALLOW OR TOO DEEP

When planting directly into the soil, don’t bury your seeds too deep. If they’re too far down, they won’t have access to enough oxygen, and moisture in the soil can overpower them and cause them to rot.

Likewise, if your seeds are too close to the surface, there is a risk they’ll dry out before sprouting, or the seed will emerge but can’t shed off its cap. The happy medium is to place your seeds about 0.5–1.0cm deep and just lightly cover them with soil.

5. NOT USING NEW OR STERILISED SOIL AND POTS

One of the biggest factors inhibiting seeds from sprouting is fungus. Old, reused soil that isn’t sterilised is likely to contain mould and other harmful organisms like bacteria and insects.

Your seeds may not sprout at all, or they may emerge from the soil but die days later. Seedlings may suddenly bend and turn brown from a disease known as “damping off”. Overwatering, poor drainage, and lack of aeration will also increase the likelihood of this.

Solution: Only plant your seeds in a sterilised (i.e. new) potting mix as this won't contain these harmful organisms. But your substrate isn’t the only thing you need to keep an eye on. You’ll also need to make sure your containers are clean, as these can also carry mould and other harmful pathogens. If you encounter fungus problems when you’re germinating, it is best to get rid of the seed and the contaminated growing medium and start over.

6. TOO MUCH MOISTURE

If your substrate drains poorly, excess water in the soil will prevent your seed from accessing oxygen, and it will encourage fungal growth. You can improve the water drainage of your soil by adding some perlite. Also, always make sure your planting containers have holes in the bottom for water to drain out.

If you’re using a hood to keep moisture in, make sure there are holes in this too. Lift the hood frequently to allow for fresh air exchange. Remove the hood as soon as your seedling has shed its shell.

7. NOT ENOUGH MOISTURE

Keeping the above in mind, seeds do need moisture to germinate. Keep your soil moist but not damp. The best approach is to use a hand sprayer with a fine mist setting. Use a transparent germination hood or cling film to keep the soil from drying out.

8. DROWNING SEEDS

Some growers like to germinate their seeds in a glass of water. While this method technically is viable, there is also a risk that the seeds will drown if allowed to sit for too long. After all, seeds need a good supply of oxygen to grow.

Instead, germinate your seeds directly in soil, or even better, use the Royal Queen Seeds Starter Kit.

9. ALLOWING SEEDS TO GERMINATE FOR TOO LONG

If you allow your seeds to germinate for too long, transplanting them safely will become difficult. The reason for this is that the longer the roots are exposed to air and light, the more likely they are to become damaged. Moreover, the longer the taproot, the higher the risk for accidental damage when transplanting.

Keep an eye on your seeds and transplant when the taproot measures 1–2cm at most.

10. POOR WATER QUALITY

While tap water may be okay for more mature cannabis plants, it can be a problem for seeds and seedlings. Tap water contains chlorine, fluoride, and salts that can be detrimental to healthy growth and may even prevent seeds from sprouting altogether.

Use bottled water for germination. If you need to use tap water, fill a bucket with hot water and let it sit outside for a day. This allows the chlorine to evaporate so the water is safer to use for germinating.

11. TEMPERATURE TOO HIGH

Excessively high temperatures in your germination environment can lead to slow and stunted growth, and it can cause your soil to dry out. The optimal temperature for seed germination is a moderate 20–25°C.

If you’re germinating indoors and temperatures are too high, see whether you can get it cooler with some fans or by opening windows. If that doesn’t work, consider an air conditioner for your grow room to keep temperatures at bay.

12. TEMPERATURE TOO LOW

Likewise, when temperatures are too low, this can introduce a whole host of its own problems, including inhibiting seeds from sprouting. Colder temperatures also increase the risk of other plant diseases. What to do about it? If you want to grow outdoors, don’t set plants outside too early. Instead, germinate indoors and allow your seedlings to grow for a few weeks.

Do your due diligence and verify when local temperatures are high enough to set your plants outside. Usually, waiting a couple weeks for higher spring temperatures is worth it!

13. TOO MUCH LIGHT

Seeds don’t need light to germinate. In fact, too much light can decrease their likelihood of popping. You only need to worry about providing light once your seedlings actually emerge from the soil. But make sure to start with low light intensity before gradually increasing over time.

14. PESTS, BIRDS, INSECTS…

Believe it or not, hemp seeds are a major component of many types of birdseed! That’s right; birds love them just as much as you do. But birds aren’t the only critters that would love nothing more than to chow down on your seeds.

Among other critters, ants are particularly keen on eating the taproots from sprouted seeds. To keep your seeds safe, use bird netting, ant traps, and other preventative measures like neem oil or slug traps. Check on your seeds often so you can spot infestations and act before they become a problem.

15. SOIL TOO FIRM

If your soil is packed too firm, this can prevent your seed from popping. Compact soil deprives seeds of oxygen, and poor drainage will increase the risk of disease and mould. Using your (clean) hands, cover your seeds with just a light layer of soil.

16. SOIL TOO LOOSE

When soil is too loose, too much air surrounds the seed, and thus it can’t absorb moisture properly. After you’ve placed your seeds, lightly pat down the soil with your fingers. When adding perlite to make your soil airier, around 10–20% is plenty.

17. SOIL TOO "HOT"

Soil being “too hot” means it contains too much nutrients. This is especially important for seeds and seedlings, as these don't really need nutrients at all. For that reason, it is best not to feed them during the first few weeks of growth.

Many commercial soils are “too hot” for germination as they contain levels of nutrients better suited for mature cannabis. Use “light” or unfertilised seedling soils when germinating.

18. CROWDED POTS

After germinating your seeds, the roots of your cannabis plants will want ample space to grow, so make sure you’re using adequately sized pots. On the other hand, only grow one seed in each pot so they aren’t competing for available light or nutrients in the soil.

If your space or resources are limited, it’s better to grow fewer plants that can flourish than to grow too many in a crowded area.