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Botany for Gardeners: The Root-Factors that Influence Root Growth

A plant with a root that does not grow is a desperate plant. It can not get the water and nutrients it needs and so will die. As gardeners, we want our plants to grow and are willing to help them do so. But what can we do? Knowing what influences root growth is the first step.

Most of our garden plants live in soil in our garden beds. True some may live in a challenging environment like a bog or a pond and these have special adaptations to deal with their severe conditions. Most of our plants, however, live in ordinary soil, and the list of factors influencing root growth below is really about them.

Here are the four most important factors that influence root growth:

1. Water: We all know that an important function of roots is taking in water but if they live in too much water they will rot. How much is too much? It varies with the plant; some plants like a constantly moist well-drained (not wet) soil, while others grow best when the soil dries out between watering. And then there are those that have special adaptations for living in water, but these are a special case.

2. Oxygen: Yes, roots need oxygen to carry out respiration, the process of using food to carry out life’s processes. A lack of oxygen also inhibits the development of root hairs, those one celled structures that greatly increase the surface area of the root and increase the roots ability to absorb water.

3. Soil fertility and pH: The amount of nitrogen, phosphorous, potassium, and trace elements are vital to the growth of the plant but the development of a good root system is especially related to phosphorous. Superphosphate, rock phosphate, and bonemeal are all good sources of phosphorus and can aid root development. pH, that is the acidity or alkalinity of the soil, can influence the availability of other nutrients to the plant and therefore effect root growth.

4. Soil Compaction: Can you stick you foot through a brick wall? Well, most plants can’t grow their roots through one either and some clay soils are like bricks when they dry out. A nice loose soil allows the root to grow freely and more rapidly than a compacted one.

Give the roots of your plants a good environment and they will grow. A loose soil with the right amount of water, oxygen, nutrients, and a favorable pH will favor good root growth and over all good plant health. This means plants that are better looking and more disease resistant. What more do we want in a garden plant?

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Recommended Reading:

From Seed to Plant
Trees: Their Natural History
Oh Say Can You Seed?