Is it best to add nitrogen to a garden in the spring or in the fall so it can overwinter?
When to Add Nitrogen to a Garden
Fertilizing rate and timing is specific to the plant involved. Some plants, like cosmos, respond to nitrogen with abundant leafy growth and few flowers. Roses and other heavy feeders require several applications of fertilizer each season for top performance. But, in general, nitrogen is applied at the product's recommended rate in spring as growth begins. A second application, at roughly half the rate, is sometimes applied in late summer. Later use of nitrogen isn't recommended since it tells the plant to produce new growth when it should be storing sugars for winter and hardening off growth from earlier. Nitrogen doesn't prepare the plant for winter. The leaves make sugars which are stored in the roots for over-wintering and leaf development next spring. To minimize winter damage, the plant needs to be well hydrated all fall, even after leaf drop.