Roots at heart of planting success

Dig into their many vital roles as days get cooler

Nancy O'Donnell, Albany Times Union

Published September 30, 2006 at midnight

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More dig!

Fall is for planting, and for good reason. It has everything to do with those underground, unsung heroes of the plant kingdom - roots.

Roots have some important responsibilities: They anchor the plant firmly in the soil and have an uncanny ability to extract water and minerals from the soil.

But roots also perform some other vital functions. Take their ability to store food. Some roots store food in such excess that they are actually harvested for our dinner table; potatoes, turnips, radishes and carrots to name a few.

Then there are perennial plants such as trees, shrubs and flowers whose roots have stockpiled food from the last growing season.

As the days lengthen and warm up in the spring, dormancy begins to break and plants need a supply of food to nourish them before they are fully awake. Roots to the rescue.

Roots also lend humankind a helping hand. Some plants, such as the willow, have the ability to absorb loads of water. They are often planted in wet areas to help control excess surface water. Other plants have such an extensive root system they are called upon to help curtail soil erosion.

Throughout the life of the plant, its roots are continually growing and dying. As they grow, they work themselves through the soil, aerating as they go. As parts die, they add to the organic matter of the soil, feeding the tiny microorganisms that aid in the decay of plant debris. So, not only are they vital to plants, but they're vital to the soil and the tiny organisms that live in it.

Plants have three types of roots: tap, fibrous and adventitious.

Taprooted plants have one main root that grows down deep into the soil; smaller roots branch off from that root. Examples of plants with taproots include carrots and dandelions.

Transplanting taprooted plants is difficult. It's best to either direct seed or transplant when the plant is very young, before a significant root has formed. The positive side is since this root grows down deep into the cooler, moister layers of soil, the plant has a good drought tolerance.

Fibrous roots are the most common. Fibrous rooted plants have a root system that branches and rebranches (no single main root) and tends to lie closer to the soil surface. Plants with this type of root system aren't as drought-hardy but are much easier to transplant even when mature. Examples include peppers, maples and Black-eyed Susans.

Adventitious or aerial roots can be found most often on vines such as English ivy. Their job is simply to help the vine adhere as it climbs; they do not perform typical root duties. If you were to dig below ground, at the vine's crown you would find a fibrous root system.

Regardless of the type of root, parts are parts. If you could envision a root, zoom in to the tip area. This is the point from which the root grows outward. If you have ever "root pruned" a tree or shrub with a fibrous root system prior to transplanting, you essentially cut off the growing tips of the roots (similar to pinching the ends of branches to make them fuller).

As a result, the smaller side roots grow and re-branch, forming a smaller, denser root ball that makes transplanting easier and more successful.

Look even closer and you'll find tiny, fine roots, called root hairs, lining tap roots and fibrous roots. It's through these root hairs that the root absorbs minerals and water.

It's important when transplanting not to allow the roots to become exposed to the drying effects of the sun and wind. These fine root hairs dry out the fastest; when they do, the absorbing power of the associated root is diminished until new root hairs grow.

Cooler soil temperatures are a favorite growing condition of roots, thus, fall is often a good time to plant.

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