Why is asparagus not growing well this year?
Question:
We planted asparagus four years ago, harvesting for the first time last year. We had a long and abundant harvest last year. This year we have experienced next to no shoots. Should we be concerned? Is there something we should do to encourage growth again next year? Are the good years and bad years for asparagus?
Answer:
My first inclination would be to verify that you are growing the bed according to best recommended practices, including:
* winter protection (e.g., laying cut fronds on the bed)
* proper water management (consistent, well-draining soil)
* seasonal perennial weeding (asparagus is a poor competitor)
* appropriate short-term harvesting followed by letting the plants grow vigorously for the rest of the season (necessary to replenish the stored resources for next year). If the “long and abundant harvest last year” went on too long, you may have overstressed the plants and not given them time to recover; each time a shoot is harvested, the plant has to use stored resources to put up another. After spring harvesting, they should be left alone to grow out and spend the rest of the season photosynthesizing and packing new resources down into the crowns.
* annual fertilizing and mulching (both critical to long term health).
I will include a few helpful resources:
UMaine Cooperative Extension Bulletin #2071, “Growing Asparagus in Maine”
Univ of NH Extension Asparagus Fact Sheet
Penn State Univ Extension “Growing Asparagus in the Home Garden”
If any of the recommended approaches are lacking in your bed, that’s where I would start trying to remedy things… and I would probably not harvest this year. If you are already following the best practices protocol, then we would think about pests or pathogens. Insect or disease activity in previous seasons can weaken the crowns, and excessively wet conditions can promote crown or root rot, which would be my next worry if the site isn’t well-draining (especially given the wet year we had in 2023). You could *carefully* excavate down to a crown or two to see if they look healthy with strong roots, or brown and slimy, which would give us an indication that there is rot. Please be careful with this tactic, though, as asparagus is somewhat fragile and doesn’t like being disturbed.
If none of the suggestions above seem to fit with what you’re seeing, let me know and I can reach out to one of our vegetable specialists.