Tree & Shrub Fertilizer Spikes


Fertilizer spikes are a convenient way for busy gardeners to keep their prized plants healthy and flourishing. They are beneficial for trees and shrubs of most types, and come from various manufacturers in different sizes and strengths. One of the best things about using fertilizer spikes on your plants is that they are time-release, so you can insert them into the soil and forget about them for several months to one year.

Development of Fertilizer Spikes

Fertilizer companies developed the technology responsible for chemical fertilizer spikes in the 1980s, when gardeners wanted quick and easy ways to make their yards into easy-care showplaces of plants. Not until the 21st century did companies introduce organic fertilizer spikes.

Brands Available

Jobe's makes an organic version of tree fertilizer spikes; special spikes are available for evergreens, which have an N-P-K ratio of 11-3-4. Miracle-Gro's fertilizer spikes for shrubs and trees have an N-P-K ratio of 15-5-10. Lutz manufactures spikes suitable for use with palms and other trees and shrubs: their spikes feed continuously for one year. Henry Field's Seed and Nursery Company makes spikes for trees and shrubs with an N-P-K ratio of 10-13-13.

Cost of Fertilizer Spikes

Tree and shrub fertilizer spikes can get pricey, with five large spikes designed for shrubs or evergreens costing $80. Each tree requires all five spikes, but they last for 60 days. Other brands cost less: for example, Miracle-Gro fruit and citrus spikes cost $9.49 for 12 spikes. Miracle-Gro's tree and shrub spikes cost $9.99 for 12 spikes. Lutz spikes are available in large quantities: their spikes for palms and sagos come 125 to a case and cost $95.40. Henry Fields Co. sells 10 spikes for $9.95.

Cautions and Hazards of Using Fertilizer Spikes

Because many fertilizer spikes contain chemical fertilizer ingredients, keep this aspect in mind if you are running a certified organic farm or orchard. OSHA has not determined Miracle-Gro fertilizer spikes to be hazardous because they do not contain more than the approved threshold limits for nuisance dusts, asbestos or inhalable particulates. However, product specifications warn not to breathe the dust and to use them only in well-ventilated areas. The manufacturer also advises users to wear protective gloves, long pants, shoes and socks when working with fertilizer spikes. Also, do not allow your eyes to come into contact with fertilizer spikes or their dust, and of course, do not eat them. As a precaution, the manufacturer advises keeping fertilizer spikes away from children.

Trees That Don't Respond Well to Fertilizer Spikes

Avoid using fertilizer spikes with pecan trees because they deliver all of their nutrients to the area where you place them, causing the roots to become burned from too much fertilizer. Other parts of the tree's root system where the spikes don't exist will not receive any fertilizer at all. Other trees that do not need fertilizers, as is the case with many native species, also will not benefit from fertilizer spikes.

Keywords: fertilizer spikes, trees shrubs, plant food

About this Author

Barbara Fahs lives on Hawaii island, where she has created Hiā€˜iaka's Healing Herb Garden. Barbara wrote "Super Simple Guide to Creating Hawaiian Gardens," and has been a professional writer since 1984. She contributes to Big Island Weekly, Ke Ola magazine, and She earned her B.A. at UCSB and her M.A. from San Jose State University.