If a landscape that I’m responsible for needs fertilizer, one of these four fertilizers will be applied: ammonium nitrate, ammonium sulfate, ammonium phosphate, or soil sulfur. In keeping with my gardening philosophy, they are the simplest, cheapest fertilizers you can buy.
I am reluctant to use combination weed killer or pest killer and fertilizer. If landscaping has weeds or pests, I’ll buy the right single-purpose product. I am also reluctant to apply “time-release” products because in my experience, they are timed for the typical Eastern lawn and garden.
Ammonium Nitrate: This is straight nitrogen for a growth enhancer. It has to be used very carefully because too much nitrogen at once “burns” the plants, doing more harm than good. It’s useful for stimulating growth in a Bermuda lawn that needs killing, or adding to a compost bin to speed up the rate of decomposition.
Ammonium Sulfate: I use this to give a lawn a boost in the spring, and simultaneously add sulfur to free up some iron from the alkaline soil. This is less likely to burn plants than ammonium nitrate, but still has to be spread lightly.
Ammonium Phosphate: Vegetable gardens and some flowering plants need phosphorus to enhance flowering and fruiting. I use this in vegetable beds, at about 1/4 the recommended dose.
Soil Sulfur: Soil sulfur is the wonder-working fertilizer for desert landscapers. The alkaline southwest soil has ample iron, but it is locked into a chemical form that plants can’t use. Scattering a pound of soil sulfur onto each 100 square feet of landscaping at the start of the summer rains liberates enough iron to keep most desert plants happy for several years. It is slow-working but reliable.
Fertilizer application tips: Don’t rely on the fertilizer package to tell you how much to use. Your lawn and garden can thrive on much less than the listed amounts, or none at all. It’s better for the plants if you apply several light doses a week or two apart than one heavy dose. Calculate how much you need, then divide it into several applications. Water thoroughly between applications.
Read about the typical available nutrients in your area’s soils. You don’t need to have expensive soil tests run unless the plants are failing to thrive. Whatever the local soil has adequate amounts of can safely be left out of the fertilizers you apply. For example, alkaline desert dirt has plenty of calcium (we call it caliche) and potassium. It is short on nitrogen, phosphorus and available iron.
Read about the requirements of the plants you are growing. Using too much or the wrong kind of fertilizer can decrease fruit and flower production, slow growth, or even kill the plants.
Don’t apply fertilizer as a routine thing, because it’s on the schedule, or because you read somewhere that it’s needed. Wait until you know the plants need it. Fertilizer runoff” is a major source of water pollution.
Fertilizers I Don’t Use: Specialty fertilizers for palm trees, citrus trees, roses, pansies, and orchids with all trace metals and minerals? I don’t use them. If I have to buy a special micronutrient product to coax a plant to do well, it’s the wrong plant. I have a long list of plants that are too fussy about their diets to bother with, and an equally long list of plants that do well with desert dirt and minimal care.
Sunset Western Garden Book, Sunset Publishing Corporation, 2001