What is a good soil mix for container gardens?

Asked November 24, 2013, 11:11 AM EST

I would like to know the best soil combinations to use for containers for growing vegetables.

Walker County Texas

1 Response

Here is an excerpt from our Vegetable Gardening in Containers (publication E-545):

Growing Media: Any growing media must provide water, nutrients, and physical support in order to grow healthy plants. A good growing media must also drain well. Synthetic or soilless mixes are well suited for vegetable container gardening and may be composed of sawdust, wood chips, peat moss, perlite, or vermiculite. These are free of disease and weed seeds, hold moisture and nutrients but drain well, and are lightweight. Many synthetic soil mixes, such as Jiffy Mix®, Bacto®, Promix®, and Jiffy Pro®, are available at garden centers. Soilless mixes can also be prepared by mixing horticultural grade vermiculite, peat moss, limestone, superphosphate, and garden fertilizer. To 1 bushel each of vermiculite and peat moss, add 10 tablespoons of limestone, 5 tablespoons of 0-20-0 (superphosphate), and 1 cup of garden fertilizer such as 6-12-12 or 5-10-10. Mix the material thoroughly while adding a little water to reduce dust. Wet the mix thoroughly before seeding or transplanting. Soil mixes are made up of equal parts of sphagnum peat moss or compost, pasteurized soil, and vermiculite or perlite. Composted cow manure is then added to improve the soil’s physical properties and as a nutrient source. Soil mixes tend to hold water better than soilless mixes.

In addition to the information above, the "recipe" that I have utilized most often in the past is very similar to the following one from an Extension publication on preparing raised beds:

An old standby formula was a 1-1-1 mix, usually one part loam topsoil, one part coarse sand, and one part organic matter (usually peat moss, although pine bark is an excellent substitute where available). This mix would make a good starting point for almost any raised bed. It is, however, relatively low in nutrients. The addition of fertilizer, using the following ratio of soil elements per cubic yard, is advised for trial: five pounds of a complete fertilizer (8-12-4, 10-20-10, 8-8-8 or similar ratio), two pounds of 20% superphosphate, and five pounds of gypsum. If a heavier mix is desired, the ratio could easily be shifted to two parts soil, one part organic matter, and one part sand. Use of a fine "bank sand" would also make the mixture denser and reduce the cost.