Using regular garden soil will make your EarthTower way too heavy and difficult to move and rotate. Our caster system was never designed for use with heavy clay soils!
Soil-less growing mixes are sterile, very lightweight and easy to handle (of particular importance to those who garden indoors or on apartment terraces).
These mixtures retain moisture well, and their spongy consistency encourages abundant root growth. Sterilized, they are free of insects, fungus, weed seeds and other annoyances. Moreover, they won’t pack down, and they deteriorate very slowly. One filling can last for years!
These mixtures are commonly composed of Sphagnum peat moss, perlite and/or vermiculite and/or coconut coir. Some brands may also enhance their mixtures with healthful amendments such as beneficial microbes, humic acid, dolomitic lime, wetting agents, earthworm castings, bat guano, kelp and other organic fertilizers. If you spend extra for these types of soils, you won't need to add plant food to your waterings as often.
Choose a soil-less mixture that feels right to you. If you prefer to make your own soil-less mixture, here are 2 simple recipes that will give you a light, well-balanced product:
2 parts screened sphagnum peat moss
NOTE: You may use regular peat moss. Because regular peat moss is quite fine, a small amount of crumbles of potting mix may fall out of your tower (especially when dry and/or when moving or rotating it). For most people, this is no big deal, because, afterall, its gardening. To avoid these occasional crumbles on your floor or patio, use long-fiber Sphagnum.
1 part vermiculite
1 part coarse perlite
Add 1 Tablespoon of dolomite lime per gallon of mixture (to counteract the mild acidity of the sphagnum peat moss).
2 parts sphagnum peat moss
1 part coconut coir
1 part vermiculite
1 part course perlite
1 Tablespoon of dolomite lime per gallon of mixture
The sterile soil-less mediums recommended for the EarthTower need not be excessive in cost. Ask your garden shop dealer for large bulk bags or bales. Don’t buy your soil in small, expensive bags. Also, your local nurseries use this sterile medium in great quantities. You might arrange to buy enough bulk soil from them to fill your EarthTower. The EarthTower holds approximately 5 CUBIC FT of soil-less growing mix. A standard 3.8 cubic foot bale of regular Peat Moss will provide plenty of plant mix when mixed according to the recipes above.
IMPORTANT: ALWAYS MOISTEN SOIL-LESS MIXTURE BEFORE FILLING THE EARTHTOWER!
Fill a large container (a large plastic bag or a used Rubbermaid bin will work well) about half full and moisten with water. Mix thoroughly, adding more water as needed until the mixture is moistened through and through.
Don’t over-moisten! It should be just damp enough so that a handful sticks together, then falls apart.
IMPORTANT: When working with a sterile mixture, use tools or containers that have not been in contact with regular soil. This extra care will prevent contamination.