Making Your Own Container Soil

Dick Englund

One thing I have noticed over the past few years is an increased interest in container gardens. They are not just for flowers any more. They are great for growing all kinds of herbs, as well as peppers, tomatoes, lettuce and many other kinds of vegetables. One catalog which came this year even had a special container in which to grow potatoes and which produced "a satisfying 13-lb. harvest." That got me thinking. Maybe if I had several of these containers I could grow most of the potatoes that we need for the year . . . . that is, if each one produced a 13-lb. harvest. You can also raise fruit in containers from strawberries to blueberries to lemons.

But what kind of soil do you use for containers? Can you just use some soil from your gardens or do you need a special potting soil designed for containers? I think you can see in which direction I am heading. While you certainly can use some good soil from your garden, youíll do much better using a good potting or container soil and youíll be much happier with the results.

Now, you can buy such soil already made or you can make it yourself. Guess which will be the less expensive? You are right on if you say the soil you make yourself. Several years ago I was given a formula for making such soil. Iíve used it for my containers since then and it is excellent. But I still had some questions about the formula until a couple of weeks ago when I received a garden catalog that advertised the ideal mix for containers which "contains sphagnum peat, perlite, vermiculite and limestone." That is exactly what I have used in the soil Iíve made myself.

Letís now make some container soil. Youíll need the following ingredients: a 3.8 cubic foot bale of sphagnum peat (which sells for around $12), 1 bag (8 quarts) of perlite, a volcanic glass which has been expanded by heat to form a lightweight aggregate (which sells for around $5 to 6), 1 bag (same size) of vermiculite which is mica granules also expanded by high heat to form a lightweight highly water absorbent material (sells for around $7), and 1 coffee can (1 lb. size) of limestone (which will cost about $1). In this case I have used the pelletized limestone made for lawns and gardens.

Now comes the fun part. I mix these together on my garage floor. After thoroughly combining them, I moisten the soil. This is somewhat of a problem since the peat doesnít take water too readily. I spray the mixture with a garden hose, but not enough to cause the water to run off. Then I mix it all together again. I repeat the process of spraying and mixing until it becomes uniformly moist but not soaking wet. This process is not that difficult to do, and it shouldnít take more than a half-hour or so. The mixture can be placed in a 30-gallon covered container. If you fill up a container and a half, it will give you about 6 cubic feet or about 45 gallons. This can all be done for about $25-26. The only thing that needs to be added as you use this soil is fertilizer. Some people also add the water-absorbing crystals to their soil, but I have not done it as I donít think it is really necessary.

How does this now compare in cost to the ready-made mixtures? I priced potting soil earlier in the growing year, and it was selling for around $8/cubic foot. If you happen to use 6 bags of such soil, it will set you back about $48. Thatís about twice what it cost me to make my own container mix. When it comes to the ready-made container mix which I mentioned at the beginning, the cost difference is even more dramatic. Each bag of the ready-made soil contained 20 quarts (5 gallons), and you would need about 9 bags to equal the amount you would get making it yourself. Each bag was selling for just under $10/bag for a total of $90 and to that has to be added the cost of shipping and handling. This would be more than 4 times the amount I paid for materials when I made my own container soil. I think I will continue to make my own container soil, thank you!

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