By Susan Cloninger
Master Gardener Volunteer
Does the shelf where you store fertilizers resemble your bathroom cabinet?
Do you need a headache formula just trying to decide which one to use? Do you loiter in the aisles of garden centers in total confusion between 10-10-10 and 15-9-5?
Occasionally, the package might add “Specially formulated for hybrid tea roses,” but you have shrub roses.
How many different fertilizer combinations does the average gardener really need?
Fertilizers are important to plant health, supplying nutrients that help make the plant’s food. These nutrients along with the sun, carbon dioxide and chlorophyll produce sugar, which is the food for plants. Plant nutrients, namely nitrogen (N), phosphorous (P) and potassium (K) are reflected in the number combination you see on all fertilizer packages.
You can determine how much nitrogen, phosphorous and potassium a specific plant needs with a soil test. Soil sample kits can be obtained from the Cooperative Extension Office in Salisbury. Soil samples are sent to N. C. Department of Agriculture’s Agronomic division for a free analysis. Soil test results give the homeowner the plant’s exact nutritional requirements eliminating guesswork.
Nitrogen is the most important mineral in the trio of nutrients. It is vital to plant growth and can be lost from the grasp of plant roots through leaching processes. Fertilizers for fescue lawns are typically high in nitrogen and will provide you many months with green lawns.
However, there are occasions when you might want to consider a fertilizer high in phosphorous and potassium.
Bulbs and flowering plants need extra phosphorous for bloom production. One caveat: phosphorous does not filter down through clay soils, so you either must add high phosphorous fertilizers as you plant, or use a water soluble liquid bloom booster fertilizer.
Also, decide whether you want to use a slow release fertilizer. These are more costly, but when accurately applied can provide months of garden value. Lawns and landscape plants benefit from slow release, but you may need more immediate results with fast growing annual flowers. Be careful not to over fertilize any area by reading and following the label directions.
For most plants ó including trees, flowers, vegetables, roses, houseplants and shrubs ó all-purpose fertilizer is fine. Peters Professional All Purpose 20-20-20 and Miracle-Gro All-Purpose 15-30-15 are two of the most popular water soluble brands. Osmocote Vegetable & Bedding Slow Release 14-14-14 and Ultra Vigoro All-Purpose 12-5-7 are two of the most popular slow release formulas.
Gardens dotted with the old Southern staples of azaleas, camellias, gardenias and rhododendron need acid-forming fertilizers that contain iron and sulfur.
For example, Miracle Gro Water Soluble Azalea, Camellia, Rhododendron Plant Food 30-10-10 or Holly-Tone 4-6-4 are specifically formulated for acid loving plants.
So start your spring cleaning with your fertilizer shelf!
Susan Cloninger is a Master Gardener Volunteer with the Cooperative Extension Service in Salisbury.