Answer: Asparagus is a hardy perennial and like all perennials fall clean-up and fertilizing are good practices to incorporate into those seasonal chores.
Clean-up should begin after the first frost. The asparagus tops should be removed to the ground to lessen the chances of fungal diseases overwintering in the foliage. With any disease it’s best to not compost this debris as fungus can overwinter and wait for spring to reinfect other plants.
Since asparagus crowns can remain in the same bed for years, one of the best and easiest ways to keep roots well fed is after cutting down the ferns, apply a thick layer of well-composted manure or compost. The spears will push right thru it in the spring. Over the winter the spears are forming, so adding this organic fertilizer in the fall will help energize the plants for the spring growing season. You should not apply a high nitrogen fertilizer to any perennial in the fall. Nitrogen encourages plant growth and lots of new growth just before frost can cause harm to the overall plant health.
Espoma’s Organic Traditions Manure or Triple Phosphate or Bone Meal fertilizer supplements can also be added to help nourish the root systems of the asparagus in the fall. They can also be added in the spring to reinvigorate plants. They also make a great fall supplement for your other perennials, as well.