Pruning is a set of techniques intended to lead the plants to various phases of their growth. This practice may seem trivial, but in fact, the rules to follow always depend on the purpose we aim.
Purpose of pruning
Pruning of deciduous trees and shrubs allows to::
- Stimulate vegetation for better growth;
- Ventilate a structure that is too entangled and doesn’t let the light through;
- Densify the branching;
- Limit the expansion of plants whose volume becomes too important;
- Improve flowering by producing vigorous shoots (usually old wood is less floriferous);
- Impose a sculptural shape on the plant (topiary art).
Tools: the must-haves
- Pruning shears for small branches
- Pruning shears with a long handle or tree trimmer for branches too big for pruning shears
- Hedge chisel for hedge maintenance
- Pruning saw for large branches
- Pruning shears on telescopic handles or long-arm pruner for high branches
- Chainsaw for heavy work
Different types of pruning
- Formation pruning
- Maintenance pruning
- Rejuvenation pruning
This pruning aims to intervene on the shape of the tree to establish a good structure and the desired shape while preserving the tree’s free shape. This is the phase of building the tree or shrub. This pruning is very important during the first five years after planting a tree or shrub, therefore when its vegetative growth is active. Formation pruning is generally in early June or early fall. It is sometimes necessary to:
- Shape and ensure the dominance of the terminal leader;
- Reshape the tree’s terminal leader after a frost or breakage;
- Remove the branches that seem to orient themselves to form a second terminal leader (head);
- Densify the tree or shrub’s branching;
- Keep a clean trunk.
Maintenance pruning is performed to remove unsightly elements from a tree and shrub or to contain their size. This pruning, carried out during the growth and fruiting phase, can be done year-round on most woody plants. However, we must take into account the flowering and the rise of sap of certain plants. This pruning consists of:
- Eliminating dead or diseased wood that can be a source of disease and a shelter for pests;
- Cutting the branches that cross and rub together;
- Removing unsightly branches;
- Removing useless branches, such as suckers.
This very severe pruning is done to restore trees and shrubs that have been neglected or have a low vegetative growth, decreased flowering or fruiting. The catching up can be gradual and done over a few years or be radical. Radical rejuvenation is done by setting it back to 15 or 20 cm (6 to 8 inches) from the ground in the fall or spring. Several shrubs respond to this treatment by emitting vigorous new shoots that will quickly reform a satisfactory leaf volume.
The following shrubs are often rejuvenated:
- Honeysuckle (Lonicera)
- Ninebark (Physocarpus)
- Rugosa Rose and its hybrids (Rosa rugosa)
Some rules for pruning
- Choose the right tool according to the work to be done;
- Use sharp tools;
- Bevel a few millimeters above an eye (bud) facing outward;
- Remove a branch from a tree by cutting it flush with the trunk, but keeping the bead close to the trunk;
- Take less than 30% of the leaf volume;
- Prune frequently so you don’t lose control;
- Disinfect tools after use with bleach.
When is the best time to prune?
- Pruning is done after flowering;
- Tall trees are pruned during dormancy, so in the spring or fall;
- Fruit tree formation pruning is done during the woody plant’s winter rest, for example in February.
Woody plants that flower on the previous’ year’s wood:
Some woody plants produce their flowering on the previous year’s wood: their pruning is carried out immediately after flowering. Here are some examples:
- Japanese Flowering Quince (Chaenomeles japonica)
- Deutzia (Deutzia)
- Forsythia (Forsythia)
- Spring-flowering spirea (Spiraea)
- Lilacs (Syringa)
- European Snowball (Viburnum opulus ‘Roseum’)
- Weigela (Weigela)
Woody plants that flower on the year’s wood:
Woody plants that flower on the year’s wood are pruned in early spring. Here are some examples:
- Panicled Hydrangeas (Hydrangea paniculata)
- Cinquefoil (Potentilla)
- Elder (Sambucus)
The following trees are pruned in May:
- Maple trees (Acer)
- Birch trees (Betula)
- Walnut trees (Juglans)
- Willows (Salix)
- Lime trees (Tilia)
What to do after pruning?
- Fertilize the plant with compost after pruning;
- Destroy diseased branches;
- Grind and compost plant wastes that are free of diseases and insects.