Fertilizing - Ask Extension
I live in a townhouse association and last year the association relandscaped my yard in the spring with mostly perennials. There is rock on top, whic...
Knowledgebase
Fertilizing #928227
Asked April 13, 2026, 11:29 AM EDT
I live in a townhouse association and last year the association relandscaped my yard in the spring with mostly perennials. There is rock on top, which I know is not the best but I have no control. The soil is poor, with rock, sand, and in some places clay. Last year I fertilized with a starter fertilizer according to package directions, but not sure what to do this year. The perennials that were planted include: rose marvel Salvia, a variety of types of astilbes, moonbean coreopsis, allium, catmint, purple flame grass, autumn joy sedum. In addition, they planted 3 winterberries. I have read not to overfertilize as it stunts flowering. I know to deadhead the rose marvel salvia. The plants did beautifully last year. How do I fertilize this year for optimal blooming in my poor soil? When do I begin fertilizing? Do I use different types of fertilizer, one with high middle number for rose marvel salvia to keep it blooming? Do I trim back catmint?
Hennepin County Minnesota
Expert Response
I have several articles that I refer to.
https://northerngardener.org/spring-perennial-care-tips/
https://extension.umn.edu/manage-soil-nutrients/quick-guide-fertilizing-plants
I like to use a slow release fertilizer and a common one is Osmocote. I follow the directions on the label. An application lasts about 90 days or 3 months. it is expensive but one doesn't need to use much. Over fertilizing plants like winter berry stimulates leaf growth at the expense of flowers.
Fertilizer can be applied as soon as the plants are actively growing or when temperatures are consistently 55 F at night. Until the nights are mild plants should be growing slowly.
Catamint can be cut back to keep it shapely.
https://www.provenwinners.com/learn/how-to/catmint
The plant selection sounds lovely.
https://northerngardener.org/spring-perennial-care-tips/
https://extension.umn.edu/manage-soil-nutrients/quick-guide-fertilizing-plants
I like to use a slow release fertilizer and a common one is Osmocote. I follow the directions on the label. An application lasts about 90 days or 3 months. it is expensive but one doesn't need to use much. Over fertilizing plants like winter berry stimulates leaf growth at the expense of flowers.
Fertilizer can be applied as soon as the plants are actively growing or when temperatures are consistently 55 F at night. Until the nights are mild plants should be growing slowly.
Catamint can be cut back to keep it shapely.
https://www.provenwinners.com/learn/how-to/catmint
The plant selection sounds lovely.
