How do I fertilize trees and shrubs?

Mature trees seldom require fertilizer because of their extensive root system. As long as a tree or shrub appears healthy and is growing at an acceptable rate - if tree shoots, for example, are growing more than 6 inches per year - there is no need to give it any additional fertilizer.

A soil test is the most reliable way to tell whether it's necessary to fertilize trees and shrubs. Ideally, a soil sample should be taken before trees are planted. Additional samples should then be taken every three to five years to check whether nutrients are lacking.

Without a soil test, certain visible symptoms can signal nutrient deficiencies in trees and shrubs. If a tree's annual shoot growth is less than 6 inches or regular foliage color appears off, then it may need some nutrient help.

In general, apply fertilizers to plants at the beginning of the growing season. For deciduous trees, fertilize when leaves appear; and for evergreens, when it turns cold.

Distress signals from shrubs, however, don't automatically call for fertilizer. The plant may have been unhealthy to begin with, unadapted to its new home, carelessly planted or improperly watered.

If you determine that fertilizing is necessary, apply in early spring or in autumn after shoot growth ceases; plants take in few nutrients during periods of active shoot growth.

Choose a slow-release fertilizer, which releases nitrogen over a long period of time, reducing the chances of overdosing or burning plants.

Always provide adequate water when fertilizing. Plants can't properly use the fertilizer without adequate water and some fertilizers may damage roots and scorch leaves if the plant isn't hydrated enough.

Don't apply liquid fertilizer at the same time you plant. Some root hairs will break, and the fertilizer will burn them. Wait two to three weeks after planting before you fertilize.

Check your state and local codes before starting any project. Follow all safety precautions. Every effort has been made to ensure the accuracy and safety of this information. Neither Westlake nor any contributor can be held responsible for damages or injuries resulting from the use of the information in this document.

Check your state and local codes before starting any project. Follow all safety precautions. Every effort has been made to ensure the accuracy and safety of this information. Neither Westlake nor any contributor can be held responsible for damages or injuries resulting from the use of the information in this document.

What's on Sale

What's on Sale

Find out what's on sale at your local Westlake.

See Ads & Specials »

Panel of Pros

Panel of Pros

Get helpful advice and tips from our panel of pros.

VIEW TIPS »