A beautiful, healthy perennial garden must have a soil that provides good drainage and aeration. Have a soil test completed to measure the fertility and texture before proceeding. See fact sheet 0.507, Soil, Water and Plant Testing for more information.
Prepare the site by removing any existing grass or other plant material in the designated bed. Install edging to prevent encroachment of lawn grasses. This also gives the bed form.
Next, incorporate organic matter (compost, sphagnum peat, or aged manure) 12 inches deep. A general recommendation is 3 cubic yards of organic matter to every 1,000 square feet. This is the equivalent of a 1-inch layer over 1,000 square feet. See fact sheet 7.235, Choosing a Soil Amendment, for more information.
Phosphorus fertilizer is best mixed into soils prior to planting. Use a superphosphate (0-20-0) if the soil test indicates that phosphorus is deficient at the site. Perennials need a balance of minerals including nitrogen, phosphorus and potassium, along with several trace elements. A general purpose mix (5-10-5) can be used annually in spring. Water it in well after application. Always follow manufacturer’s recommendations when applying fertilizers.