hemp seedlings hardening off
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Planting Hemp

When April arrives in Maine it’s time to start planting the hemp. This allows the plants to mature enough to identify any males before they go in the ground in June. I like to plant in the days approaching the first full moon in April.

Although “feminized” hemp seed is now the norm at most seedbanks–eliminating males whose pollen will fill the female flowers with seeds–I prefer regular seed. Partly because the mother plants aren’t deliberately stressed in the feminization process and partly because it allows me to do some breeding. While some growers like clones for genetic consistency, they won’t root as deeply as a plant from seed will, making them more susceptible to wind damage and drought. Plus seeing the variation in phenotypes grown from seed is interesting.

hemp seedling
This hemp seedling is just one week old and is just starting to spread its first set of real leaves.

April in Maine can mean anything from a blizzard to 70 degree sunshine so the hemp is always planted indoors, moved into cold frames outside in May, then transplanted into the ground once the frost danger has passed (after Memorial Day).

soaking hemp seeds
Soaking the seeds in water for no more than 24 hours just before planting helps improve germination rates.

The day before planting I soak the seeds in water, then plant directly into moist potting soil (an organic seed starter mix is ideal). I like to lightly moisten the medium first, so it’s slightly damp but not sopping wet, then fill small seedling trays and plant the seeds about 1/2″ deep. They need to be kept warm and moist until the seeds germinate, usually 1-6 days.

seedling trays ready for planting seeds
Seeds are planted in lightly dampened organic seedling mix (left hand tray) or potting mix (right hand tray). Use your finger to create a hole about 1/2″ deep.

Once the seedlings emerge from the soil they need lots of light. I use LEDs because they use very little power.

hemp seedlings emerging from soil
After a few days, the seeds germinate and tiny delicate seedlings emerge into the light.
hemp seedling
Within a few days after emerging the seedling will spread out its first set of real leaves.

In 2-3 weeks the seedlings start to outgrow their little trays so they get up-potted to gallon containers filled with a premium organic potting soil (I’ve had great results with Coast of Maine’s Stonington Blend which is made locally and designed specifically for cannabis).

hemp seedling at 4 weeks
After 2 weeks the seedlings are transplanted into 1-gallon pots, then moved outside to coldframes to begin hardening off.

As soon as the seedlings have settled into the bigger pots they get moved outdoors to cold frames with a transparent plexiglass lid that can be closed if it gets too cold, rainy, or windy. Here the seedlings grow accustomed to the intense outdoor sunlight, which is many times brighter than the indoor lights. They grow quickly at this point and by the end of May most of them are showing their sex and the males can be separated from the females. Females will get transplanted into the ground around the first new moon in June, by this time they should have 6 or 7 sets of leaves and be able to withstand the elements.

hemp seedlings in cold frame
These 8-week old seedlings are just about ready to transplant into the ground now that the frost danger has passed.

It’s always remarkable watching a tiny seed the size of a peppercorn transform into a big bushy hemp plant. By the end of August some of them will be over 9 feet tall!

newly transplanted hemp plant
Once the danger of frost has passed, usually by Memorial Day, the young hemp plants are transplanted into the ground. Mulching is key, both in preserving moisture in the ground and encouraging the growth of microorganisms and other soil life that help the plants thrive.

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