Published on 04/18/02

Amend Soils for Landscape Success

The old saying, "Never place a $5 plant in a 50-cent hole," is true. The condition of your landscape soil may be the most important aspect of gardening success.

Whether you work with south Georgia sand or north Georgia's clay soils, soil amendments are vital commodities to have.

But it can boggle the mind to look around the garden center and try to distinguish between soil amendments. There are manures, top soil, potting soil, peat moss, mushroom compost -- and the list goes on.

The important things to remember are the goals of soil amendments: to improve the soil's tilth (loosen it up) and drainage and perhaps possibly add some nutrient value.

Focus on Loosening Soil

I suggest focusing more on organic amendments' ability to loosen the soil and less on nutrition.

The price of amendments varies greatly, and the bags whose fancy covers tout their nutritional excellence may not be any better than the others.

Get in the habit of reading the label on everything to see what's actually in the bag you're buying. By reading the label, you can more easily compare apples to apples.

Stay away from just buying pure peat moss. This makes a poor soil amendment on its own. It tends to dry out too much during dry times and stays soggy when the weather's wet.

Home Compost Good, Too

Home compost can be a good soil amendment, too, if it's been composted completely. Completed compost should have the consistency of dark topsoil. Use partially finished compost as a mulch on top of the soil, or leave it in the compost bin to finish its conversion to humus.

Once you've decided on an amendment, it's vital to add it to your soil the right way.

One of the most common errors in planting is to dig a hole, pour in a soil amendments and then insert the plant into a hole you'd need a shoe horn to get it into. This will spell disaster. The moisture level around the plant will fluctuate drastically over time.

The right way is to create a consistent, universal soil the roots of the plant can expand in. Then, in this amended soil, dig a planting hole at least twice the width of the root ball.

New Planting Sites

If it's a new planting site, incorporate a 3- to 4-inch layer of the organic amendment into the soil. This is best done with a tiller in larger beds, but a spade or stiff pitchfork will work in small spaces. Be sure to thoroughly mix the organic matter into the native soil. Don't create two separate soil layers.

You can add organic matter to existing landscapes, too. Just rake back some of the mulch and lightly incorporate about a 1-inch layer around plants. Use a pitchfork to work some of the soil into the existing medium.

Take care not to damage your plants' root systems. Amending existing landscape beds annually will greatly improve the growing conditions for the plants and help insure against compaction and poor drainage.

Take a Soil Sample

While many amendments will add some nutritional value to your soil, you will most likely need to supplement with synthetic fertilizers.

Taking a soil sample to your county extension agent is the best way to know the true fertilizer and lime requirements. Sampling every other year will allow you to closely monitor your plant's nutrition needs.

Amending your soil can be one of the easiest ways to avoid plant stress or prevent future disease problems. It's a great way to improve the health of your soil and ensure the long-term success of your landscape.

Bob Westerfield is a University of Georgia Cooperative Extension consumer horticulturist with the College of Agricultural and Environmental Sciences.