Lawn Care Guide

How to Fertilize Trees & Shrubs

All living things need nourishment, and trees and shrubs have a big appetite.

It’s true, large, well-established, and healthy trees may not need much supplemental feeding, but fertilizing smaller trees and shrubs will pay you big dividends in return for your feeding investment during their first several years on your property. Your payback will include better resistance to disease and insects, improved flowering, and a quicker establishment than similar plants denied regular fertilization.

At Spring-Green, our tree and shrub care experts help you master the art of fertilization. Here are a few tips to keep in mind as you’re fertilizing the trees and shrubs in your own lawn:

Tip #1: Give your plants a balanced diet.

The primary nutrients nitrogen (N), phosphorus (P) and potassium (K) are all used by your trees in different ways.

  • Nitrogen encourages fast trunk and branch growth, and the production of healthy and dark green leaves.
  • Phosphorus stimulates vigorous root growth (which makes it especially beneficial to recently planted trees and shrubs).

Phosphorus also promotes flower bud formation and increases resistance to cold.

  • Potassium makes the trees stronger, helping them to withstand wind and ice breakage as well as diseases.
  • Iron is often added to fertilizers for trees to unlock the other nutrients, or make them more available to the plant.

Micro-nutrients, like iron, are needed in some soils and for some types of plants that are prone to specific deficiencies.

Tip #2: Make sure the feeder roots of your trees have access to the fertilizer.

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 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.

Tip #3: Apply fertilizer to trees early enough to withstand cold weather conditions.

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.

Things to remember when fertilizing trees and shrubs:

  • 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 September 30 after trees start dormancy or resting periods.

If you would like to see your landscape investment start paying better dividends to you through regular shrub and tree maintenance, contact your neighborhood Spring-Green. We know trees and have solutions that work, in addition to our years of lawn care service experience for the rest of your yard.

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