A seed hull is the outer shell of a seed, which often detaches during sprouting and must be removed before harvest. In home gardening for sprouts and microgreens, hulls are a practical concern because they affect texture, appearance, and shelf life of the finished product.
Hull behavior varies by seed type. Sunflower seed hulls are large, hard, and conspicuous — they cling to cotyledons and must be removed by hand or by rinsing under running water. Broccoli and radish hulls are smaller and often wash away during the rinse cycle without extra effort. Some seeds, like chia and flax, produce a mucilaginous coating when wet that makes hull separation difficult, which is one reason these seeds are less commonly sprouted.
Leaving hulls in the harvest is not dangerous but degrades quality. Hulls are fibrous and often bitter, and they trap moisture that accelerates spoilage. The standard practice is to remove loose hulls during the final rinse before harvest by floating them off the surface of a bowl of water or by gently agitating the sprouts under running water. For microgreens grown in trays, hulls are less of an issue because the growing medium holds the seed in place and the cotyledons push free of the hull as they expand.