When to Stop Cutting Asparagus

Q. When should you stop cutting asparagus? We've had a good crop again but seem to have quit harvesting too soon in prior years so want to go as long as possible, we enjoy eating it!

Asparagus is harvested or cut just above the soil surface. It is best not to leave the severed spears too far above the soil surface or it gets in the way of weeding and other management practices. Cutting below the soil surface allows diseases to enter the plant.

A. The textbook answer is 6 to 8 weeks of cutting and then you should let it go and rebuild its crowns beneath the soil for next year’s harvest. That information was back when asparagus spears were thought to be marketable only if they were the diameter of your thumb.

Three grades of asparagus based on diameter of the spear. The highest quality asparagus has spears large in diameter. The smaller diameter asparagus is becoming popular as a lower-cost alternative. Asparagus produces a lot more small spears than the largest ones.

            That’s kind of changed and now we see asparagus much smaller than that and marketed as such. The other answer is to continue to harvest until you see a noticeable decrease in the diameter size of the spears. When they start to get too small for harvesting, stop and let the beneath ground part of asparagus rebuild itself.

When planting asparagus the crowns are planted 12 to 18 inches apart and 8 to 10 inches deep. I like to plant them on either side of drip tape or drip tubing in a triangular pattern with rows that are wide enough to walk between and harvest.

            Asparagus will rebuild itself better if you can provide some nutrients as the crowns are putting away storage for next year. So after harvesting, laid down at least an inch of rich compost or you can also use manure.

Purple asparagus is a novelty which brings a little higher income but purple varieties do not produce as many spears. They have a higher sugar content and are a bit sweeter than the green types. I stick with varieties that have done well in the hot Southwest such as the University of California or UC types. Purple Passion has done well for me.

            The crowns should be 6 to 10 inches deep depending on the soil so laying manure on top of these areas should cause no problems. Make sure you water it in and don’t water too often because the crowns are fairly deep. Put them on a similar irrigation cycle to fruit trees if they are planted deep.