Why Didn’t My Hemp Seeds Germinate?

Nothing is more disappointing than racks of newly-seeded trays of hemp seed starts that fail to germinate. Or, do so poorly. Hemp isn’t particularly difficult to germinate, but there are a few basics to keep in mind for good germination rates and healthy young hemp seedlings.

Here at Colorado Breeders Depot, we have a few tips for reliable hemp seed germination:

• Start with good quality seed.
• Use correct sprouting medium.
• Maintain the proper temperature.
• Check your humidity.
• Keep your hemp seeds in the dark.
• Only use pure water.

Start with Good Quality Hemp Seeds

If you start with hemp seeds with low germination rates, it doesn’t matter if you do everything else right; you’ll still only have as good of germination percentage as they are rated for.

The seed you purchase should have been tested that year by a third-party certifying agency for germination rates and the seed breeder should provide that information for every varietal. Ideally, you want germination rates of 90 percent and above. Sometimes seed breeders might sell a batch with a lower germination rate, but that is usually with a discounted rate and the understanding that the grower will have to plant more seed to germinate their planned number of starts.

Seed breeders should have kept their seed in dry, pest and temperature-controlled facilities to remain good viability until planting. Ask about their procedures before you buy from a new hemp breeder! Once you receive your seed remember to keep the seeds in similar conditions until you are ready to plant. Don’t let your seeds get moist or damp before planting.

Use the Proper Seed Starting Medium to Germinate Your Hemp Seeds

Using the proper seed-starting medium is crucial to success when germinating your hemp seeds. Backyard hemp growers just growing out a small percentage of starts may want to germinate their hemp seeds in water or wet paper towels and then pot them up, but larger-scale hemp farmers don’t have the time for that extra step. So, making sure to start with the right seed-starting medium is crucial.

There are many different seed-starting mediums that hemp growers use — Jiffy pellets and rockwool are two examples — but whatever you use, make sure your seed starting medium doesn’t have any nutrients in it. Frequently inexperienced growers think that they should plant their seeds in potting soil formulated with nutrients for good growth. However, those additives are two powerful for the tender young seedling stage.

Make sure the plug size you plant your seeds into isn’t too big. You want your young seedling to be able to quickly grow and fill out it’s root system into the pot so you can plant a firm (but not root-bound) young start when it’s time to plant. Other tips are to water in your seed-starting medium (if possible) BEFORE you plant the seeds and when you plant the seeds, plant them ½ inch deep and firmly tamped down the soil.

Maintain the Proper Temperature for Good Hemp Seed Germination

Some plants germinate better with temperatures that go up and down. Hemp, however, is not one of them!

Assuming you are starting your hemp seeds in a greenhouse, you want to maintain air temperatures of at least 68 degrees and not above 90 degrees. If direct-sown outside (like for a fiber or tri-crop varietal), hemp seeds can germinate in soil temperatures as low as 35 degrees but do best when the soil warms up to 50 degrees. The key is to remember (even in a greenhouse) is that the soil temperature is usually cooler than the air.

Some variability between daytime and nighttime temperatures is okay, but ideally, keep your temperatures as consistent as possible until you have a good stand of young hemp seedlings.

Keep an Eye on Your Humidity Levels

Keeping your humidity levels in the proper range, along with adequate watering, will keep your soil from either drying out or getting too wet and help with good germination.

Improper humidity can lead to all sorts of mold, damping off and disease issues. Humidity is also crucial for young, just germinating seedlings because their root system is not yet established. Proper humidity allows water intake through the plant’s leaves.

A humidity monitoring system is an excellent idea to add to your seed-starting grow room. Keep humidity above 60% and below 80 % (65 to 75% is ideal) and document your humidity every day to catch variables you might not have noticed.

Keep Your Hemp Seeds in the Dark During Germination

Hemp seeds need to be well covered with soil or even kept in a dark room until germination.

Some plants, like lettuce, need light to germinate their seeds. But hemp requires dark. Be careful when you are watering not to blast your seed flats (use gentle misting or bottom watering instead) because that can inadvertently cause your seeds to float up to the top. Also, making sure your seeds are planted deep enough and the soil is firmly tamped down (covered above) keeps the light from the seeds until the seedling has germinated.

Don’t forget though, once your seedlings have germinated (even just a little bit!) to add sufficient light. Otherwise you will quickly have weak and leggy hemp starts.

Only Use Pure Water for Germinating Hemp Seeds

Not watering with pure water is a mistake we see many farmers succumb to when germinating their hemp seeds.

Once your seedlings are well established and definitely after they are planted out, they are not as picky about what’s in the water, but young hemp seeds are very sensitive to water issues. High minerals, too low or too high of a PH, or other unwelcome nutrients in your water can keep your seeds from germinating. We recommend installing a reverse osmosis system to prevent any potential water problems from the get-go in your grow room.

Still Struggling with Germination? Don’t be Shy — Ask for Help!

Sometimes just a simple thing can make all the difference for a successful hemp seed germination.

If you’re still struggling, don’t be shy; give Colorado Breeders Depot. We’d love to help you out.  Hemp seeds have so many benefits, it’s worth doing your due diligence. We also evaluate, consult and advise our hemp growers, from assessing the market potential and risk to teaching you how to grow hemp. Helping our customers have an excellent hemp harvest — starting with the seed they plant — is our goal.