Crop Rotation: Why and How
Crop rotation is the practice of moving plant families between beds on a seasonal or annual cycle. The reasons are practical: disease cycle interruption, soil nutrition management, and pest management.
The core principle: many soil-borne diseases and pests are host-specific. Clubroot (Plasmodiophora brassicae) attacks brassicas exclusively. If brassicas leave the soil for 3-4 years, the resting spore population declines to non-damaging levels. Potato cyst nematodes behave similarly. Rotation starves them.
The nutrition angle: legumes (beans, peas) fix atmospheric nitrogen through root bacteria. Planting leafy vegetables after legumes (nitrogen-demanding crops) lets them use the fixed nitrogen without artificial fertiliser. Heavy feeders (squash, corn) follow; finally root vegetables, which are moderate feeders and break up compacted soil.
GreenPlot's three-year rotation plan: Year 1 — legumes + roots. Year 2 — brassicas + alliums. Year 3 — fruiting vegetables (tomatoes, peppers, cucumbers). Adjust for bed size and local disease pressure. The planner generates a bed-by-bed grid showing this three-year sequence with optional fourth year reset.