It’s finally feeling like fall. If you haven’t already, you need to be working on some of those outside fall garden activities.
Cut peony foliage back to the ground if this hasn’t been done already. Compost or discard foliage. A total of 1.5 to 2 ounces of a 1-1-1 fertilizer such as a 10-10-10 or 13-13-13 per plant per application should be used. This amounts to 3 to 4 ounces of fertilizer per year. If a soil test reveals adequate levels of phosphorus and potassium, use a lawn fertilizer such as a 29-5-4, 27-3-3 or something similar, but cut the rate to 1/3 of the above rate. In other words apply 1/2 to 3/4 ounce per plant. The lawn fertilizer should not be a “weed and feed.”
Never apply fertilizer directly on the center of the peony as the buds (eyes) may be damaged. Rather, place the fertilizer in a band from 8 to 18 inches from the center of the plant. Water the fertilizer in so the plant can take it up.
Winter protection of herbaceous peonies is only necessary the first winter after planting to prevent alternate freezing and thawing from lifting plants out of the soil. A couple of inches of mulch should be sufficient. Any organic material that does not mat down will work and should be applied after the ground freezes. Avoid using leaves that will mat together. Remove the covering before growth begins in the spring.
The less common tree peonies have woody stems like deciduous shrubs and should not be cut back to the ground or pruned in the fall. Collect the shed leaves and place in the compost pile this fall. Though tree peonies are hardy to Zone 4, they do benefit from a light mulching over winter. Also, it is recommended that tree peonies be fertilized during November to get the plants off to a good start next spring. It is best to take a soil test to see what nutrients are needed. If the soil needs phosphorus and potassium, use a complete fertilizer at the rate of 2.5 pounds per 100 square feet. This would equal one rounded teaspoon per square foot.
If phosphorus and potassium are not needed, blood meal makes an excellent fertilizer. Apply at the rate of two pounds per 100 square feet or one teaspoon per square foot. Turf fertilizers such as a 27-3-3 or 30-3-3 also can be used but at the rate of to one pound per 100 square feet or one teaspoon per two square feet.
This article was written by Ward Upham of Kansas State University and edited by Amanda Mosiman. Mosiman is the Ag and Natural Resource Extension Educator for Purdue Extension-Warrick County. She can be reached at firstname.lastname@example.org or 812-897-6100.