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Knowledge to Grow by Karen Weiland - Dirt on Dirt

A good potting soil is the basis for a great container garden. In order to know what soil mix is best for the type of plants you are growing, you should know the basics of what soil does.

    Soil needs to hold moisture and nutrients around the roots of the plant and provide enough air so those roots will be able to breathe and not rot. Soil also acts as an anchor for the root system.

    Soilless or artificial media is made up of various ingredients such as peat, vermiculite, ground coconut hulls and bark. Each manufacturing company has its own recipe depending upon what type of plant is being grown. For instance succulents and perennials prefer a mix that is well draining where a tropical plant will prefer a mix that holds moisture.

    Never use straight garden soil no matter how good it may look or how well plants grow in your garden. You can however make your own potting mix by using one part garden soil, one part peat moss and one part perlite. Keep in mind that by using your own mix it may contain insects, weed seeds and disease organisms. Store-bought soilless media are usually free of these things. A soil-based mix is going to be heavier than a soilless mix which may factor into what to use in a hanging basket. On the other hand, a soil-based mix will not dry out as fast and will hold onto nutrients longer than its counterpart.

    To make a soilless mix go farther you can mix 25 percent soil with the soilless mix. When using a soilless mix, moisten it first by placing the mix in a tub, fluff the mix and add water to dampen it.

    It is possible to reuse a soilless mix from year to year as long as there were no major disease issues with the plants that were growing in it. As time passes, the organic materials that the mix is made up from will break down and decompose, thus losing its drainage and aeration properties. It can then be dumped into the compost pile or garden.

    Filling very large containers can become quite costly. Here’s my Frugal Fanny tip – fill the bottom of the container with non-biodegradable packing peanuts, empty water bottles, milk jugs, or aluminum cans. Place a sheet of landscape fabric over the filler material, then fill the container with your growing medium of choice to within one inch or so of the top of the container. Leaving an inch or better at the top will enable the water to pool in the pot and not run off when watering. Using a filler will also decrease the weight of your container.

    As always, Happy Gardening!

    More information about gardening and related subjects is available online at



    The Purdue University Cooperative Extension Service can be reached at 499-6334 in LaGrange County.