Outdoor growing calendar: when to plant, what to watch for, when to harvest

Outdoors, the sun runs the calendar. Dates below are approximate for the northern United States, so check your local frost dates.

Rough timeline (northern hemisphere)

Photoperiod plants flower when nights get long enough, but don’t apply a single dark-hour threshold to every outdoor cultivar. The cited Moher experiment used tissue-cultured pieces of one genotype, not field-grown plants. Night lighting can interfere with photoperiod responses depending on its intensity, timing and duration, so choose a site away from avoidable night lighting.

Caterpillars

Check buds regularly. Corn earworm was identified in a review of hemp pests as having the most potential to ruin buds. Some Bacillus thuringiensis products target caterpillars, but strains and permitted uses differ. Only use one if the exact label and current local regulator allow it for the crop, pest, site and timing. A hemp label isn’t automatically a marijuana authorization. Observe all preharvest restrictions, and don’t improvise sprays on flower.

Rain and mold

Bud rot begins inside dense flowers and is worst when buds stay wet. Choose genetics that finish before your wet season, thin the center of the plant for airflow, and make sure any rain shelter has adequate airflow and safe support. A tightly wrapped cover can trap humidity and make things worse.

Short seasons

If your summer is short, autoflowers or early-finishing photoperiods give the best chance of a clean harvest.

Latitude, cultivar and local frost and rain patterns matter more than a universal calendar. Hardening off means gradually adapting plants to outdoor sun, wind and temperature. Check current home-cultivation, visibility, security and plant-count requirements before planting.