Root Pruning - a lost art
Root pruning is far from an exact science and has been out of favour for the past few years except for the treatment of damaged or dangerous roots. Traditionally, it was mainly employed by fruit growers as a means of restricting luxuriant top growth developing at the expense of' flowers and, in consequence, fruit.
Root pruning can be used in the greenhouse and home to reduce the vegetative growth of plants in borders and induce flowering, restrict the size of pot plants, get rid of dead and badly developed roots, and give a new lease of life to root-bound plants.
In the open ground roots have an almost unrestricted run. A root-bound plant gives a much better insight to the amount of root a plant will develop if growth is prevented from reaching its full potential due to lack of space and nutrients.
The first problem to overcome when handling roots is lack of knowledge. There is nothing magical or mysterious about roots just because they are out of sight. Basically, roots have three functions: they take in a plant's food, water, and are the plant's support system. Structurally, unlike leaves, flowers and stems, the roots of all plants are the same. Naturally there are a few modifications ‑ dahlia tubers, are storage organs, some orchids develop aerial roots to absorb moisture from the atmosphere and the adventitious roots seen in ivy.
In glasshouse beds the need to root prune can be avoided. Instead of allowing a free root run, the roots are contained by planting inside a large bottomless container, like an old drum. Roots are given a reasonable amount of space to develop without allowing rampant growth. As the container is left open at the bottom, plants are not short of moisture. When it comes to replanting plants can be easily lifted without too much disturbance to adjacent specimens.
Large glasshouse shrubs, trees and climbers that have been allowed a free root run and got out of hand can be tackled in two ways.
1. It will be necessary to root prune in situ. This is accomplished by digging a narrow trench round the plant, about 45‑60 cm radius from the stem and as deep as the roots go. All the roots are then cut as they are exposed, cutting through them cleanly with a sharp knife or pair of pruners.
Once all the roots are cleanly pruned round the side, undercut the root ball and cut off any tap roots. This operation needs to be done with care, doing a portion at a time so that the root ball does not break up. Once the operation is completed, back fill with fibrous compost, firming well.
Root pruning must be carried out in the dormant season. The effect of this rather drastic treatment will be apparent almost as soon as growth starts. Shoots will be shorter and less succulent and the production of flowers should be increased.
2. In the case of a small shrub or climber, it can be lifted from the ground, have all the roots cleanly cut back, reducing the size of the ball and be replanted.
As pruning roots seriously reduces a plant's ability to take up water extra watering may be necessary in the early stages of growth during the spring. To balance the reduced root system, top growth can be cut back. Water well when replanting and keep moisture up to the plant.
Root pruning can be used in the greenhouse and home to reduce the vegetative growth of plants in borders and induce flowering, restrict the size of pot plants, get rid of dead and badly developed roots, and give a new lease of life to root-bound plants.
In the open ground roots have an almost unrestricted run. A root-bound plant gives a much better insight to the amount of root a plant will develop if growth is prevented from reaching its full potential due to lack of space and nutrients.
The first problem to overcome when handling roots is lack of knowledge. There is nothing magical or mysterious about roots just because they are out of sight. Basically, roots have three functions: they take in a plant's food, water, and are the plant's support system. Structurally, unlike leaves, flowers and stems, the roots of all plants are the same. Naturally there are a few modifications ‑ dahlia tubers, are storage organs, some orchids develop aerial roots to absorb moisture from the atmosphere and the adventitious roots seen in ivy.
In glasshouse beds the need to root prune can be avoided. Instead of allowing a free root run, the roots are contained by planting inside a large bottomless container, like an old drum. Roots are given a reasonable amount of space to develop without allowing rampant growth. As the container is left open at the bottom, plants are not short of moisture. When it comes to replanting plants can be easily lifted without too much disturbance to adjacent specimens.
Large glasshouse shrubs, trees and climbers that have been allowed a free root run and got out of hand can be tackled in two ways.
1. It will be necessary to root prune in situ. This is accomplished by digging a narrow trench round the plant, about 45‑60 cm radius from the stem and as deep as the roots go. All the roots are then cut as they are exposed, cutting through them cleanly with a sharp knife or pair of pruners.
Once all the roots are cleanly pruned round the side, undercut the root ball and cut off any tap roots. This operation needs to be done with care, doing a portion at a time so that the root ball does not break up. Once the operation is completed, back fill with fibrous compost, firming well.
Root pruning must be carried out in the dormant season. The effect of this rather drastic treatment will be apparent almost as soon as growth starts. Shoots will be shorter and less succulent and the production of flowers should be increased.
2. In the case of a small shrub or climber, it can be lifted from the ground, have all the roots cleanly cut back, reducing the size of the ball and be replanted.
As pruning roots seriously reduces a plant's ability to take up water extra watering may be necessary in the early stages of growth during the spring. To balance the reduced root system, top growth can be cut back. Water well when replanting and keep moisture up to the plant.