How to Install Tree Spikes


Fertilizer tree spikes contain slow-release fertilizer and are designed to be inserted into the soil around trees to provide the appropriate amount of fertilizer over an extended period. Although more expensive than granular fertilizer, many gardeners prefer the convenience of installing the spike to the effort of calculating fertilizer needs and applying the fertilizer manually. However, the nutrient levels in spikes may not be high enough for some trees, such as evergreens. In such cases, granular fertilizers may be the best option costwise, according to Deborah Brown, extension horticulturalist for the University of Minnesota.

Step 1

Assemble the tree spike by placing the plastic cap over the top of the spike.

Step 2

Locate the drip line of the tree. The drip line corresponds to the edge of the canopy when foliage is present.

Step 3

Measure the circumference around the tree, following the drip line.

Step 4

Refer to the manufacturer's recommendations to determine the number of spikes required for the area around the type of tree being fertilized.

Step 5

Push the spike into the soil so that the top of the spike is 2 inches below the surface of the soil. Repeat the placement at equal intervals around the drip line of the tree.

Tips and Warnings

  • Do not insert fertilizer spikes within 2 feet of the tree's trunk. If the drip line measures less than 2 feet from the base of the tree, insert the spikes farther out so that they are 2 feet from the trunk.


  • University of Minnesota Extension: Fertilizing Evergreens
  • NC State University: Guide to Fertilizing Trees and Shrubs
  • North Dakota State University: Fertilizing Trees

Who Can Help

  • Landscape America: Fertilizing Trees
Keywords: fertilizer spikes, fertilize trees, tree fertilizer spikes

About this Author

Nannette Richford is an avid gardener, teacher and nature enthusiast with 4 years experience in online writing and a lifetime of personal journals. She is published on various sites, including Associated Content. Richford holds a Bachelor of Science in secondary education from the University of Maine Orono and certifications in 7-12 English, K-8 General Elementary and Birth to age 5.