Our first year of field trials we planted over 15 acres of seed by hand. Each seed was placed carefully below where our drip tape would drip. After filling the lines with water, they expanded and dripped nowhere near where we had actually planted the seeds. The spring was cool and dry. Virtually none of our seeds germinated and we ended up starting a whole new round of seeds in our greenhouses to fill the field.
Unless soil temperatures reach into the 60s, and moisture levels remain constant, cannabis seeds simply will not germinate. If you have less than ideal amounts of either, rates will be sporadic. We discovered in our direct sow field trials in 2019, the wetter the better, and found higher germination rates in areas where we absolutely saturated the soil. Rates will generally always be lower than those started indoors, but if you have an overhead watering system it is a technique to consider.
Pictured above is a gorgeous row of plants grown at Horn Creek Hemp. Seeds were directly sown into the soil in mid June and the plants grew exceptionally well. In this case the experiment was performed on just one small row, and by highly skilled farmers. The results were encouraging.
This is Paul Murdoch of Horn Creek's take -
"Direct seeding produces much more robust root structure, which leads to stronger growth and greater resistance to pest and disease. No question the plant was a better specimen. I planted that row Sunday, June 16. Our conventional starts were put into seed trays in early May, for planting around June 1. The direct seeded plants surpassed others in September and developed little if any botrytis.
I planted each seed in ¼” hole with compost on top.
Germination rate was not as good as greenhouse – 60% vs 95%+. And as you point out, keeping them wet is a challenge.
Direct to soil also requires more weeding on a micro scale as the seedling gets its start."
While we look forward to learning more tips and techniques for direct seed application, we still suggest farmers continue to start seeds in trays in greenhouses for the fastest and best germination rates. If you've experimented with direct sow field trials, we'd love to hear from you.
To learn how we recommend growers germinate our seeds, please check our resources section.