Yield (tonnes per hectare)
Full production is only reached after about five years. Conservative: 5 tonnes Average: 8 tonnes Good: 12 tonnesHarvesting
Harvesting should start in the second year to give the asparagus crowns time to mature and strengthen. Full production should be reached by the fifth year.
The best way to harvest asparagus is by hand with a chisel-shaped knife. Soon after the asparagus spears emerge from the soil and before the tips have a chance to spread, they are cut off about 50 mm below the surface producing asparagus spears of about 200 to 250 mm in length.
Do not leave the asparagus to grow too long above ground as it loses its crisp tasty flavour and hardens. Asparagus can also be harvested by a mechanical harvester, but this is a non-selective process so although faster and cheaper it can reduce yield by up to 40%.
Storage
Asparagus is very perishable and is best marketed as soon as possible. Harvest and cool the asparagus at between zero and two degrees centigrade.
Relative humidity in the storage facility must be kept above 90% to prevent drying of the spears.
At these condition asparagus can be kept for 14 days. Asparagus must be stored and kept in a vertical position because the spears continue to lengthen after harvesting.
If they are not stored like this they could become crooked and therefore unmarketable.