The Root of it All

This article was first published on 05 Apr 2017.

The major function of roots is to anchor the plant to the ground and to reach water and nutrients.

From the moment a seed germinates or a cutting takes, roots are growing and need care to ensure they remain strong and healthy. When buying container plants check to see they are well established but not root-bound. When planting, create a spacious planting hole to allow the roots to establish well.

Generally going unnoticed and unseen, root health and growth is strongly influenced by soil conditions. To ensure the success of your plants, consider what is going on underground.

Most plants need soil that is moist but well-drained. If soil is continuously water-logged, it becomes anaerobic and roots can literally drown. Some plants, such as New Zealand forest tree, kahikatea, tolerate varying degrees of water-logging, however the feeding roots need access to aerated soils. To achieve this, kahikatea roots grow in the less water-logged soils at the surface, allowing the roots to breathe and absorb nutrients.

In a forest community they can be heavily intertwined, which also provides the extra strength needed to keep tall trees upright. The root system of the largest trees must be strong enough to support massive above- ground weight buffeted by winds, rain and even snow.

One of the giant redwoods, Sequioadendron giganteum in Dunedin Botanic Garden, just above the rock garden, is well over a hundred years old. The visual result is the tree’s trunk and foliage is enhanced by an incredible display of exposed roots growing on the cutting above the gravel driveway.

This article is produced by Dunedin Botanic Garden. For further information contact Marianne Groothuis.