Every landscape design I do is accompanied by the caution to avoid the use of artificial soil additives. Materials found in nature are normally preferable (note that not everything found in nature is good), and are often less expensive. Some should be blended into the soil, some go on top of the soil—so follow directions. Here?s a brief description of some:

Organic fertilizers:
These work fantastically, and do not contain any filler material of questionable origin which is never disclosed on the bag. Nor do organic fertilizers have abnormally high levels of nitrogen or harmful salts, which probably will cause you to water your lawn more often. Everything that?s in it is needed for healthy plant growth, and will not harm children, pets or birds.

Corn meal:
This naturally stimulates beneficial soil microorganisms, which control fungal diseases that might otherwise attack your plants. It also helps make nutrients more available to plants, acting as a mild fertilizer. Some people use it to control algae in ponds and other water features.

Corn gluten meal:
Not to be confused with the above (on penalty of a brown garden), corn gluten meal is what?s called a pre-emergent: it stops seeds from germinating. For unwanted growth, it?s best applied about March 1 and again on June 1. Just avoid spreading it where "good" seeds are planted (it won?t kill growing plants at all).

Native soil:
No matter how disgusting yours seems, leave it and improve it naturally. (Of course, remove large rocks and such. You can even cultivate it, but never get rid of it.) The native soil is what our native trees and flowers are genetically accustomed to growing in. If the soil is made too "good," our native plants may respond by not growing. Especially if you?re planting a tree, save the soil you dig up, and refill the hole with it, possibly mixing in a little organic matter.

Compost:
This is easily the best form of organic matter. (It?s the product of a natural process, such as takes place in a forest, where it could take decades.) However, compost can be made quickly at home or is sold at lots of places. It is full of microscopic beneficial organisms, it?s loaded with nutrients, and it recycles things like old leaves, pruned-off branches, dead shrubs and grass clippings that could otherwise wind up in landfills.

Volcanic sand:
This sand helps plants grow when mixed into your native soil, unlike concrete sand or the kind of sand you can buy for a sandbox. Primarily it helps preserve the moisture in the soil, so you have to water the yard less. It also makes nutrients found naturally in all soils more available to your plants, so you need to fertilize less. There are several kinds available, and several brand names. Often called "lava sand," it?s especially good at keeping moisture in the soil.

Texas green sand:
A deposit mined from ancient seabeds, it?s packed with organic matter and trace minerals. It also contains a high percentage of iron and is nontoxic, so it is an excellent iron supplement for your plants.

Ironite:
This is a naturally occurring mineral that has been used in agriculture for years. There is no man-made chemical process involved. Ironite does many things, among them is that it?s a mild fertilizer, stimulating root growth and fighting the natural deficiency of iron common in area soils. It also helps plants take up the nutrients found naturally in even the most unpromising dirt.

Neem oil: Derived from the Neem tree (which grows in India and Burma), neem oil is biodegradable and is a botanical insecticide. It?s primarily used to control grasshoppers by disrupting their growth cycle. Neem oil can also control spider mites, aphids and whiteflies, as well as controlling most kinds of fungus. Sprayed on plants, it makes them unappetizing to many insects (ordinary soap and water will do this too).

Zeolite:
This is an underused material (sold under several brand names, such as Norit) especially for those of you who have used all sorts of chemicals in your yard, but now want to go straight. Basically it holds certain elements, releasing them to your plants with perfectly natural efficiency ? or not releasing the unnecessary ones at all. So it has proven detoxifying properties as well as an ability to deodorize.

Every one of these is effective and they?re sold under a variety of brand names by responsible garden centers and feed stores.