When to Stop Cutting Asparagus

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

Asparagus spear called 'Purple Passion' harvested

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 given back when asparagus spears were thought to be marketable only if they were the diameter of your thumb. That’s changed and now we see asparagus sold much smaller in diameter than that and marketed as such.

Asparagus spears will produce spears large in diameter at first but after the crowns get exhausted from production the spears will get smaller and smaller in diameter. It is up to you when to stop harvesting them. But in the older days, asparagus spears were harvested until the spears got smaller in diameter and smaller.

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 (don’t just look at one spear but take an average), stop and let the roots and crowns of asparagus rebuild themselves.

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

In late December or early January the asparagus bed is fertilized with either manure or a rich compost. Sometimes a fertilizer is required if no manure or rich compost is available.

            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. (Some manure is high in salts.) Planting the crowns deep makes sure the spears don’t come up too early. Make sure you water it after planting. After planting don’t water too often because the crowns are deep. Apply water on a similar irrigation cycle as fruit trees. The roots and crowns should have water available at the same depth.

Asparagus crowns are planted 8 to 10 inches deep. In retrospect, I would have used more compost when planting and made the planting area darker...more organics in the soil.