Fertilising is an important landscape management practice that help plants and grass to grow optimally by providing all nutrients that may not be present in soil. Amending soil with fertilisers strengthens roots and shoots and increases flowering and fruit production. Plants like trees, shrubs and newly seeded lawns establish better with the addition of fertiliser. Fertilisers have a specific shelf life or storage life, and the expiration period differs with type of fertiliser.
Dry Fertilizer Expiration
Dry fertiliser comes in granular form and, according to the Scotts Miracle-Gro Company, these fertilisers have an indefinite storage life and do not expire. However fertilisers referred to as weed and feed that also contain pesticides or herbicides may not be stored indefinitely. Since the majority of pesticides are no longer potent after about four years, this is the expiration time of weed and feed fertilisers as well.
Liquid Fertilizer Expiration
As the name suggests, liquid fertiliser comes in a liquid form and has a faster rate of absorption in soil as opposed to the dry fertilisers. However, liquid fertilisers have the disadvantage of a shorter shelf life than dry fertilisers. These products expire in between eight and 10 years and cannot be stored indefinitely.
Choosing the Right Fertilizer
The decision to use liquid or dry fertiliser should be based on the absorption rate of the material in the soil. This decision is also based on the type of plants being fertilised and the season. Nearly all dry fertilisers take between 24 to 72 hours to get absorbed in the soil. Liquid fertilisers have a faster absorption rate, less than 24 hours.
Methods of Application
Plants use dry and liquid fertilisers differently. Dry fertilisers first get absorbed into the soil, and the nutrients are then gradually absorbed by the plant roots. Dry fertilisers are either applied mechanically with the use of broadcast spreaders and dry spreaders or scattered by hand. Liquid fertilisers are primarily absorbed by the plant foliage and are applied with spray bottles or hose end sprayers for larger landscapes.
- University of Florida Extension; Fertilizer Recommendations for Landscape Plants: Gary Knox et al.; February 2002
- Lawncare Business: Liquid or Granular Fertilizers
- Scotts Miracle-Gro Company: Feed Any Season
- Washington State University Extension; Pesticide Storage and Disposal; Mary Robson; September 2000
- Outside Pride: Liquid Lawn Fertilizer
- University of California Extension: How to Apply Fertilizer