- In general, amended soil mixes without garden soil are the preferred growing medium for container gardens. Soil mixes are available at local nursery and garden centers and come in a variety of products. Some potting mixes contain no soil at all, but sterile ingredients such as peat moss and perlite instead. Others are made specifically for certain types of plants, such as acid-loving azaleas or rhododendrons. Choose a coarse, well-drained potting mix for perennials and herbs that require good drainage and a slightly dry soil. Use a finer product for tropical plants and succulents. (ref. 1, 2)
- Soil mixes are a good choice for container gardening because they are lightweight and have good drainage. Soil-less mixtures are sterile, meaning that they are free of diseases or weeds. Regular soils are heavier and may develop a crust when used in container gardens.
- Buying a commercial potting mix works well for a few containers, but quickly becomes expensive if you are planning a large container garden. For a more economical solution, make your own from 1 part peat moss, 1 part garden loam and 1 part vermiculite or perlite. Add a slow-release fertilizer, based on the container size and package directions. Another way to keep costs down in a large container is to fill the bottom of the pot with empty soda cans, packing peanuts or crushed milk jugs.
- Garden soil is a suitable additive to a potting mix only when the soil is sandy or sandy loam. Heavy clay soils absorb water and don't drain well. They are usually cold and don't allow oxygen to circulate freely through the soil. These characteristics are exaggerated in a container and stunt the plants' growth. Don't use garden soil that may harbor diseases, weed seeds or insects.
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