Lavender is planted, for example, next to roses to keep aphids away. Nasturtiums on the other hand are planted so that the aphids colonize them and spare the adjacent plants.
Chamomile, lilies, coreopsis, marigolds and coneflower combat nematodes. Scorpionweed (Phacelia), yellow lupine (Lupinus), buckwheat (Fagopyrum), red clover (Trifolium), winter oilseed rape (Brassica napus), sunflower (Helianthus), crimson clover (Trifolium incarnatum) and winter rye (Secale) function as green manure and improve the soil structure.
Chamomile, lilies, coreopsis, marigolds and coneflower combat nematodes. Scorpionweed (Phacelia), yellow lupine (Lupinus), buckwheat (Fagopyrum), red clover (Trifolium), winter oilseed rape (Brassica napus), sunflower (Helianthus), crimson clover (Trifolium incarnatum) and winter rye (Secale) function as green manure and improve the soil structure.