Buckwheat Fagopyrum esculentum. Buckwheat cover crop seeds produce hardy annual, upright plants. It grows so fast it can reach 1m (3′) tall in only three weeks. Then it blooms with white flowers, attracting pollinating insects and beneficial hover flies. This cover crop grows densely enough that it can be used to smother out competing weed species. Within ten days of blooming (or at any time before) it can be cut and tilled under to improve tilth and add organic matter. A succulent, brittle plant that can break down completely into the soil in a matter of days. When breaking ground for a new garden, grow two consecutive crops. Digging them in will provide ample organic matter to stimulate the soil biology. Frost will kill tender annual. 500g covers approximately 74m2 (800 ft?).