By now, perennials are starting to fade but they will benefit from 0-20-0 super phosphate fertilizer scattered around the plants at recommended doses and lightly cultivated into the soil. Next spring you’ll have stronger plants with more flowers. Use a hand applicator or wear gloves and lightly scatter.
Fall is also a great time to fertilize shrubs and trees. In my opinion, all trees and shrubs need fertilizer, because most of them are located in mulch beds that use up nitrogen as they decompose and we tend to keep them pretty with mulch which does not offer much in the way of nutrition. In addition, every fall we rake leaves off these beds, depriving plants of the nutrients that decomposing leaves would traditionally release. To compensate, I recommend applying one to three pounds of bone meal or blood meal. Both are natural fertilizer and if applied in Sept., Oct., November there will be sufficient residual levels in the Spring to start the plants off to a good start in the Spring.