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Getting to the Root of the Plant

Norma Evans

Roots are unquestionably very important. After all, they hold plants and trees in the ground. They also absorb and store both water and mineral nutrients required for plant and tree growth. Roots keep perennials alive all winter. It must be a case of out of sight, out of mind. In gardening texts, when you look in the index under roots, references are few and far between. Gardening in the shade is never referred to as gardening over or between roots. In spite of the fact that roots arenít "in" in gardening circles, by increasing your knowledge of how roots function, you will have a greater understanding of how to have healthier plants and landscapes.

Plants are mostly sold in square or round pots or cell packs. You cannot see the roots until you remove the plant from the container. The roots of a mature healthy plant should be reaching out of the drainage holes and the tips of the roots should be white. Sometimes the roots have filled the pot and then some, in other words the plant is pot bound and this puts the plant under stress. In both instances, the roots need to be teased, untangled and if necessary cut apart with a knife so that they can be spread out in the planting hole. This will ensure that your plant settles into the ground and starts growing and supporting the stems, leaves and flowers as quickly as possible.

Gardeners are applying more and more mulch every year to reduce garden maintenance and display plants more prominently. However, roots benefit from mulch big time. Mulch reduces water loss and maintains the soil at a more even temperature allowing roots to grow and function more efficiently; thereby resulting in healthier plants. In the fall, there is another bonus to using mulch as it allows roots to continue growing later in the season.

Most plants should be planted in the ground at the same level as they are growing in the pot. There are a few exceptions, tomatoes being the most familiar example. Tomatoes will produce roots from the stem so it makes sense to put them a bit deeper in the ground. A local guru and grower of clematis, recommends planting these vines anywhere from 4 to 6 inches deeper in the ground to improve growth. Conversely peonies planted too deeply will not bloom. Peonies should be moved in the fall. Gardeners are often reminded of this timing but the reason is rarely given. Peonies have a taproot that produces small root hairs in the spring to support the plant all summer. These die off in the fall so moving plants at this time wonít disturb these extra roots.

Most gardeners are aware that some plant roots can poison other plant roots. The juglone produced by both the roots and leaves of butternut and black walnut trees affects some plants more than others. This effect is called allelopathy and is being researched considerably at this time, mostly for farm crops. In Greece in 300 BC Theophrastus who was called the "Father of Botany" noticed that chickpeas tended to exhaust surrounding soil and kill off nearby weeds. I have had a similar experience with sunflower roots and there is quite a discussion on the web as to whether this is a problem or not. The hulls of sunflowers will definitely affect whatever is growing in the vicinity of a well-used feeder.

At one time, it was thought that trees should be fed at the drip line because that was where their growing roots were located. This idea has long since been put to rest as it is now known that tree roots can travel anywhere from 22 feet to 60 feet from the base of the tree. Trees have feeder roots that are mainly found in the top 6 to 12 inches of soil. Their woody roots rarely penetrate deeper than 4 feet. Any compaction of the soil by paving or construction activity can affect root efficiency.

Generally plants and trees have either fibrous or tap roots. Fibrous root systems are excellent for erosion control. Anyone who has dug or divided rhubarb is familiar with a taproot. Most roots are adapted as food storage organs, and can store sugars and carbohydrates. Some do so more efficiently than others. Most of us have roots stored in our kitchens. Sweet potatoes are an example of fibrous root storage. Carrots and parsnips are examples of taproot storage.

Letís root for roots; they deserve more respect. Without them we would starve.