Can Fertilizer Lose Effectiveness?

Dry Fertilizer Effectiveness

• One of the commonly used fertilizer formulations is the dry material. This comes in granular form and is applied by spreading around the plants on the soil. Dry fertilizers are frequently used for amending the soil around trees and shrubs. Fertilizer in the dry form does not lose effectiveness and remains viable for an indefinite period of time, as cited by the Scott's Miracle-Gro Co.

Liquid Fertilizer Effectiveness

• Liquid fertilizers have the advantage of a more rapid absorption rate in the soil. Also, there is less potential waste of fertilizer before full absorption by the plant. However, liquid fertilizer comes with the disadvantage of limited effectiveness. Fertilizers in liquid form only remain viable for eight to 10 years, according to the Outside Pride Co.

Fertilizers With Chemicals

• There are certain instances under which dry fertilizers, otherwise with an unlimited shelf life, have reduced effectiveness. Dry fertilizers that also contain some type of chemical such as herbicide or pesticide have reduced efficacy. The frequently used weed and feed products that contain fertilizers plus herbicides fall in this category. Since chemicals are effective for about four years, as cited by the Washington State University Extension, dry fertilizers that contain them are only effective for that period as well.

Fertilizer Application Tips

• The best way to make sure that fertilizers are fully used by the plants is to apply them when the plants have a requirement for them. General application times are in spring, fall and winter. It is not recommended to fertilize during dry and hot weather conditions as low amounts of water reduce plant capacity to absorb nutrients. Avoid fertilizing in late summer and early fall as the resulting new, succulent growth is prone to winter damage as it is not sufficiently cold hardy.