Healthy plants require healthy soil

Credit: Contributed

Credit: Contributed

Soil is essential for most plant growth. I say most because many plants can grow in water or hydroponically. You would probably laugh at me if I said to you that much of the Miami Valley had good soil.

The truth is our native soil is not all that bad. However, we start to see problems whenever there is construction. The soil gets compacted by equipment which leads to our “poor” soils for planting.

We have a lot of clay in our soil. Clay particles are pretty good for soils. Clay has a great capacity for holding onto nutrients. On the other hand, compacted clay soils are not useful.

If you have never done a soil test, I would encourage you to do so at least once, especially if you are a vegetable gardener or plant annual flowers each year in the same spot. This will give you an idea of your pH and the nutrients in your soil.

Our new Master Gardener volunteer interns did a soil test of their gardens during their class training. Many of them were very surprised at the amount of phosphorus and potassium that was in the soil.

Again, this is due to the nutrient-holding capacity of clay particles. Many gardens don’t need phosphorus or potassium added because of the amount in our soil.

Credit: Contributed

Credit: Contributed

Nitrogen is the nutrient needed for foliage growth. It does not stick around in the soil; it leaches out or is used by the plant. Therefore, nitrogen is the most limiting factor in plant growth.

Fertilizer is needed for optimal plant growth. In the nurseries and greenhouses around our area, they fertilize regularly as they want big healthy plants to sell. Once you get them home, you may or may not fertilize.

If you want to “push” growth, particularly early in their years, fertilize regularly. If you are happy with the way they look, you may not fertilize at all. Particularly if you have clay soil that has phosphorus and potassium.

Where do they get the nitrogen for growth? From the air and rain, and if they are legumes, they make their nitrogen.

If you have compacted clay soil, the best remedy is to add organic matter every year to help build soil aggregates. These aggregates are made up of sand, silt and clay particles as well as microorganisms, microbial “glue,” and all the other materials such as organic matter, insects, earthworms, etc.

DO NOT add sand to our clay soils. You can’t add enough by volume to get to a loamy mix.

Organic matter can be compost, composted manures, bark mulch that breaks down over time, peat moss, and more. Mix about two inches of organic matter into approximately six inches of soil.

Since the organic matter breaks down over time, adding it each year won’t hurt your garden.

Pamela Corle-Bennett is the state master gardener volunteer coordinator and horticulture educator for Ohio State University Extension. Contact her by email at

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