Asparagus season starts in January and February in warmer areas and will continue into spring across the country, but a new technique from Taiwan can extend the asparagus-harvesting season wherever you live. Commercial growers in the subtropics developed the mother stalk technique to grow asparagus more efficiently. However, it has broad application to home gardeners in this country, too.
In spring, instead of harvesting all the spears as they emerge from the soil, let the first three large spears per crown grow to ferns. Then begin harvesting the other spears as they emerge. By leaving the first three spears, the crown is being constantly fed by these ferns, so you can harvest asparagus weeks longer than normal -- right into August in zone 6. The early production will be lower than normal, but overall production from spring through summer may be higher because you're spreading out production and harvest time.
If you still want most of your production in spring, you can harvest half of the asparagus bed the normal way -- cutting all large spears for six to eight weeks -- and the other half using the mother stalk technique. The technique works best if you grow vigorous hybrid varieties such as the Jersey series and if you keep the beds well watered. If the diameter of new spears becomes smaller than a pencil width, stop harvesting and let all the ferns develop.