That means it’s time to fertilize!

Well-established and healthy trees may not need much supplemental feeding, but fertilizing smaller trees and shrubs is very important. Your payback will include better resistance to disease and insects, improved flowering, and much quicker establishment than similar plants denied regular fertilization.

How And When Tree Fertilization Should Happen

Fertilizing trees should put the nutrients within reach of the feeder roots. This means feeding an area that reaches from about 1/3 of the distance from the tree trunk to the drip line (on the inside) to a spot about the same distance outside the drip line. Fertilizer needs to be placed into holes that are about 6 to 12” deep throughout this area. For good distribution, you may need up to 10 feeding holes per inch of trunk diameter up 6 to 12” deep throughout the target area (a tree 5” across may need 50 or so holes in the feeding zone). That’s a lot of holes, but it assures that the fertilizer will be evenly available to the tree.

Trees can be fertilized anytime between when the sap goes down in fall or winter until about mid-July (at the latest). Fertilizing trees between July and fall stimulates late growth that gets no chance to harden off and is more susceptible to damage from winter cold and winds. Early spring is probably the ideal feeding time, but with slow release materials, any time during the window will give excellent results.

Newly planted trees and shrubs benefit the most from regular fertilizing during their first 5 years in the landscape. In establishment, growth, and flowering, there is just no comparison between plants that are fed and those left to go it alone.

Remember:

• Feeding of recent transplants during the first 5 years helps plants mature quickly.
• Balanced fertility is important. Nitrogen, Phosphorus, and Potassium each perform distinct functions in your landscape plants.
• Don’t fertilize trees between July 15th and Fall after trees start dormancy or resting periods.