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A Quick Guide to Fertilizing Mississippi Landscapes

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Publication Number: IS1977
View as PDF: IS1977.pdf

A Quick Guide to Fertilizing Mississippi Landscapes

Why Fertilize?

To supply nutrients to achieve a clearly defined objective, such as—

  • increasing shoot growth, root growth, flowering, or fruiting.
  • establishing newly planted trees and shrubs.
  • enhancing foliage color and plant appearance.
  • correcting or preventing nutrient deficiencies.

When to Fertilize?

It is best to fertilize only when your plants need it. The reasons in the “Why Fertilize?” section will help you make this decision.

Landscape plants should be fertilized only during the growing season (March to October). Late fertilization may lead to winter damage.

Fertilization for most ornamentals and turf should be done in several applications over the season. Established trees and shrubs probably need to be fertilized only once in the spring.

Early fertilization of turf may lead to disease problems in the spring.

Organic vs. Inorganic Fertilizers

  Pros Cons

Add organic matter that helps improve soil structure and feeds soil microbes.

Slow release

Has N-P-K and many micronutrients.

Large amounts of fertilizer may be required to achieve fertilization goals.

Smell (sometimes).

Salt content may be high.


Generally higher nutrient contents, so you need to apply less.

Quick and slow release forms available.

Can find single-nutrient fertilizers (e.g., iron-only) and complete fertilizers.

May require such a small amount of fertilizer that it is hard to apply.

No benefit of adding organic matter.

High salt content may cause burning if overapplied.


Which Fertilizer to Use?

Select fertilizer that has only the nutrients you want to add.

Complete fertilizers containing nitrogen (N), phosphorus (P), and potassium (K) (potash) can be used on landscapes and turf. It is generally best to look for an N-P-K ratio of 3-1-2 (for example, 18-6-12 or 24-8-16).

Slow-release fertilizers provide nutrients to plants a little at a time and are less likely to be leached from the soil and/or promote excess flushes of growth.

For a list of organic and inorganic fertilizers for use on landscapes, see Mississippi State University Extension Service Publication 2572 Organic and Inorganic Fertilizers and Materials for the Home Gardener.

Table 2

Fertilizer Tips

Use soil and/or foliar nutrient analysis to determine whether you need fertilizer.

Information on soil testing is available at your county Extension office or online at

Soil may be modified in order to improve nutrient uptake or plant responses to fertilizer.

Lime for acidic soils (low pH); sulfur for basic soils (high pH).

Adding organic matter (compost, etc.) can help with many nutrient deficiencies.

Soil pH should be considered when selecting the fertilizer.

Ammoniacal N tends to acidify soil around roots.

Nitrate N tends to raise pH around roots, but overall effect is neutral.

Urea lowers soil pH in the long term.

Chelated Fe (and other micros) are used for high pH soils.

Rule out other causes.

Insects/mites Cold damage
Nematodes Pesticide damage
Disease Soil compaction
Too much water Air pollution
Not enough water

Don’t try to fertilize your way out of a problem.

Many pest and disease problems only get worse with excessive fertilization.

Lawn fertilizers having some portion of N source as “slow release” will provide a more uniform growth rate and extend the period between applications. This is especially helpful with centipede and carpetgrass lawns.

Information Sheet 1977

By Geoffrey C. Denny, Assistant Extension Professor, and Karl K. Crouse, Associate Extension Professor, Plant & Soil Sciences.

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Portrait of Dr. Geoffrey C. Denny
Assistant Extension Professor
Plant Evaluation and Nursery & Greenhouse Production

Your Extension Experts

Portrait of Dr. Keri Denley Jones
Laboratory Coordinator
Soil Testing Lab

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