We recommend that if possible, leave the tops for winter mulch. This mulch will catch snow and protect the plants from severe cold, while adding moisture. During the establishment years, fern growth, plant vigor, and health should be optimized with very careful cultural management. A full harvest season may follow the next year, however, if at any time the spear size is reduced to pencil size, the harvest should halt. Asparagus harvest in Kansas normally starts about the middle of April and runs until the first of June.
Spear growth depends on temperature.
Harvest while the tips of the spears are still tight. Spears should be hand harvested when 6-8 inches long. A knife can be used to cut the spears below the soil surface or they may be snapped at the soil surface. Cutting must be done carefully to avoid damaging the developing spears and the crown below the soil surface. The advantage to cutting spears is that if you are going to hold the asparagus for several days, the woody base restricts water loss, preserving the upper spear quality.