Since asparagus is a perennial plant, you will not be able to start harvesting asparagus until the second year of growth, if you started from crowns. If you started your asparagus bed from seed, it will take three years before your first harvest.
As a perennial, asparagus needs time to grow undisturbed in order to establish itself and build a good strong root system before being harvested. Be patient, once it is well-established it will provide you with spring stalks for a decade or two!
Begin harvesting asparagus in the spring of the second year. Harvest all spears the plant makes for the first 2-3 weeks of the season, when they are 4-7” long. It’s okay this year to make this light harvest of spears, but don’t take too much or the plant will not grow to the size and strength it needs to supply you with good harvests in years to come.
If the spears are left to grow too long they will be woody and tough. By harvesting early when the spears are only 4-7" long, you may also beat the asparagus beetle larva to the harvest.
In the third year, extend the harvesting of all spears produced to 4 or 5 weeks, and from the fourth year on you should be able to take all the spears the plant sends up for the first 6-8 weeks of the season.
With experience, you’ll get to know when it’s time to stop harvesting, because the spears will start becoming thin. Let the plants recover and grow for the rest of the season.
After the asparagus fronds have died down in the fall, cut the dead stalks and remove them, and then rake the surface as clean as you can of all plant debris. Removing the dead fronds will discourage the overwintering of asparagus beetles, which go dormant in plant refuse, coming to life to feed on the young spears and lay eggs in the spring. After the plant residues (with their attached beetles) have been removed, you can then mulch heavily over the asparagus bed with fine leaf mulch, straw or compost.
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