Making your own homemade garden soil mix is easy, cheap and can help you meet your plants' individualized needs. Once you understand the basics of ingredients, composting and pasteurizing, you can begin creating recipes that will help each plant in your garden grow to its full potential.
The ingredients you use in your soil mix depends on your plant and garden type. Heavy sand can be useful in container gardens, as it helps prevent large plants from tipping over and improves air circulation. Peat and spaghnum moss are high in acid and hold water well in containers. Perlite can improve drainage and substitute for sand. Vermiculite is light and allows air and water to reach new seedlings. However, these ingredients are not recommended as amendments for existing soil. Compost and other organic materials, such as grass trimmings and manure, are excellent sources of nutrition for traditional in-ground gardens.
Compost is a key multipurpose ingredient for many container and traditional garden soils. For a two-week compost, begin with a 4-inch layer of leaves, followed by a 2-inch layer of grass clippings. Continue layering until the pile reaches 4 feet high. Then add a final layer of kitchen scraps such as eggshells, coffee grounds, nutshells and vegetable scraps. Using a pitchfork, mix the materials together, lightly wet the pile and cover it with a black garbage bag. Turn the pile every three days.
To pasteurize soil and free it of harmful diseases and bugs, place moist soil or compost in a metal pan and cover it with foil. Place a food thermometer in the soil and heat the oven to 250 degrees Fahrenheit. Once the thermometer reads 140 F, allow the soil to cook for thirty minutes. Make sure to remove the soil promptly, as overheating can harm soil structure.
Container Garden Recipes
For an all-purpose mix to suit a range of plants grown in containers, mix 1 part compost, 1 part sand, perlite or vermiculite and 1 part topsoil. A good blend for succulents includes 1 part coarse sand, 1 part perlite, 1 part peat moss and 2 parts sterilized topsoil. Leafy plants will grow well in a mix of 2 parts peat moss, 1 part sand and 1 part perlite. If you plan to start seedlings indoors and transfer them to your garden later, use a mix of 2 parts peat moss, 2 parts compost and 1 part vermiculite.
Existing Garden Soil Improvement
You may amend existing soil with fresh or composted material. Fresh materials such as leaves or fruit will decompose quickly and are more nutritious, while compost is free of weeds, undesirable seeds and diseases and will remain in the soil longer. To add amendments, use a garden spade to work in 7 gallons of compost for a 10-by-10-foot garden. If you are growing carrots or other deep rooted vegetables, work the compost in to a depth of 12 inches. For an easier method, spread a layer of the same amount of organic matter on the soil and then plant. Although it will take longer, the material will eventually seep into the soil while keeping soil structure intact.