Raised Beds for Cannabis: Build and Fill Them Right
Raised beds for cannabis lift the root zone above ground level, which improves drainage and keeps soil loose. Kentucky State notes some hemp growers use raised or mounded beds for drainage and aeration, and Oregon State says hemp does not grow well in wet soils. Build on sunny, level ground and test the soil before you fill.
Why Grow Cannabis in Raised Beds?
Oregon State says hemp grows best in loose, deep, well-drained soils and does not grow well in wet soils, which can restrict root and shoot growth (Oregon State EM 9239). Kentucky State notes that some hemp growers use raised or mounded beds to improve drainage and aeration (Kentucky State). Our post on the best soil for growing outdoors covers soil types.
When Do Raised Beds Help Most?
University of Maryland Extension says raised bed soil drains well, reducing the risk of waterlogging and root rot, and is less compacted because no one walks on it (UMD Extension). The trade-off is faster drying, which needs more monitoring and watering in hot weather. Beds help most on heavy or poorly drained ground, so see where to grow outdoors.
Source: University of Maryland Extension (vegetable crops, not a cannabis test).
Recommended raised bed depths for vegetable crops
| Crop group | Depth | Source |
|---|---|---|
| Leafy greens, beans, cucumbers | At least 8 inches on hard surfaces | UMD Extension |
| Peppers, tomatoes, squash | 12 to 24 inches on hard surfaces | UMD Extension |
How Deep Should a Raised Bed Be?
Maryland Extension’s vegetable guidance for beds on hard surfaces is at least 8 inches deep for leafy greens and beans, and 12 to 24 inches for larger crops such as peppers, tomatoes and squash (UMD Extension). These are vegetable figures, not cannabis tests, and Maryland Extension gives no depth for cannabis.
What Should You Fill a Raised Bed With?
Maryland Extension advises sunny, level ground with good drainage, testing soil quality, and adding topsoil, compost and possibly soilless mix as needed (UMD Extension). It suggests organic matter at 25% to 50% by volume for beds with garden soil. Oregon State advises testing soil months before planting (Oregon State EM 9239). Topping beds with mulch is also common.
Once your beds are built, you can pick from our outdoor seeds.
Sources
Some sources below studied hemp or other crops rather than drug-type cannabis, and their findings are reported as results for those crops.
- Oregon State EM 9239: Soil, Seedbed Preparation and Seeding for Hemp
- Kentucky State University: Organic Hemp for Cannabinoid Extraction
- University of Maryland Extension: Growing Vegetables in Raised Beds
Kind Seed Co intends this raised bed guide as general growing information, resting on the sources above.
FAQ
Do raised beds help on clay soil?
Oregon State says clay soils cause problems with excess wetness and tillage, and that hemp does not grow well in wet soils. Maryland Extension notes that raised bed soil drains well and reduces waterlogging and root rot, so beds are one way to lift roots above poorly drained ground.
Do raised beds dry out faster?
Yes. University of Maryland Extension lists faster soil drying as a disadvantage of raised beds, requiring more monitoring and irrigation, especially in hot, dry weather. Beds placed on hard surfaces dry even faster because roots cannot reach water in the soil below. Maryland Extension lists that extra irrigation as a trade-off of raised beds.
Why do hemp growers use mounded beds?
Kentucky State University's organic hemp guide says some growers use raised or mounded beds to enhance drainage and aeration, and that drip irrigation helps water transplants while they establish. Maryland Extension adds that mounded beds without walls skip the cost and work of building an enclosure.
Should you test soil before filling a bed?
Yes. University of Maryland Extension advises assessing soil quality first to decide whether to add topsoil, compost or soilless mix. Oregon State recommends testing soil several months before planting hemp and applying lime and fertilizer as needed, which leaves time for amendments to work before the season.
