Hello. We planted our asparagus in 1992 & have harvested more than we can eat for many years (love to share). Year before last we covered the bed area with thick layer of saw dust (yellow pine), & we added nitrogen on top. That year we harvested as normal. Last year we only had tiny stalks & not much of that. We did not even harvest, but let it go. The sawdust has rotted away some by now, but the harvest is still lacking. Some maybe 3/8-inch diameter stalks, but mostly very thin. We are in zone 7, piedmont NC just out from foothills area. QUESTIONS: Have we made a big mistake using sawdust as mulch for our asparagus bed, or could it possibly be aging out? Would you know the lifespan of asparagus plants? THANKS so much for insight you can give.
Holly,although I do not advocate using sawdust in the vegetable garden, the most likely issue is that your asparagus plants have simply reached the end of their life cycle. Asparagus can normally be harvested for 15-20 years, after which, they start thinning out and eventually stop producing.
The reason I don't recommend using sawdust is the high carbon ratio. As the sawdust decomposes, it depletes nitrogen from the soil. Shredded leaves are a much better option.
Sawdust, after a one year composting period, is an effective mulch, especially around bushes and trees.
I hope this answered your question. Good luck, and feel free to write again if you ever need assistance.