Pruning Basics

A weekly blog present by a Kephas landscaping Inc, a Calgary based year round landscaping, tree services, snow removal company.

When to prune?

Trees, conifers and shrubs are either deciduous or evergreen and, because they grow differently, they need to be pruned at different times.

Deciduous plants lose their leaves in autumn and become dormant in early winter. That means if you are to prune during this time there will be no sap flowing from the wounds. Also airborne bacteria or other pathogens are not present in winter.

Birch trees which are common in Alberta are notorious for losing water if pruned in spring - a wound will drip for days, forming wet puddles on the ground directly below the cut branches.

During winter with the lack of leaves it is easy to spot branches that are diseased or rubbing together and it is no problem to get close enough to remove them. The exception of the Prunus family, they need to be pruned in the summer to prevent the spread of fungal diseases. Summer pruning is also essential for trained fruit trees, the excess growth is removed to retain the shape of the tree and build up fruiting wood.

Evergreens retain there "leaves" and as a such are never dormant. There is less sap activity in winter and plant continue to growth. It is ideal to prune a conifer from the inside to be able to see where to make good cuts.

Habit of Growth

It is vital to know the species habit of growth to time the pruning accordingly. It may be needed to selectively thin some of the oldest branches from the centre of the plant, and whether or not the plant is quick or slow growing. Some plants are tolerant of a hard pruning in which some of the oldest branches are removed close to the base. If the shrubs or conifers have been neglected and are need of a rejuvenation they can be cut to the stump which will produce strong new growths.

Plants that produce berries or fruit shouldn't be pruned until the cop is harvested or the display of berries is finished.

What to prune

The three D's of trees or plants are dead,diseased, and damaged branches. Prune out all the unwanted material back to a suitable healthy bud, side shoot, or main branch.

Inspect the tree thoroughly before proceeding with pruning. Removing a branch or limb and not noticing a canker beside is can result in a oddly shaped tree. It is ideal to collect all of the diseased material and burn it, because some small pieces that are over looked and left lying on the ground or in long grass will continue to produce spores and spread the disease to other plants.

Crossing branches should be next to go. Try to keep the center of the plant open to encourage air movement and allow light into the heart of the plant. With some fast growing shrubs a years neglect will allow branches to cross from one side of the bush to the other. They may cause congestion in the center of the plant or causing rubbing against other permanent branches. It is ideal with trees to remove these branches while they are small to avoid later having larger wounds when they are removed.

Shaping

It is a good practice to picture the plant after the pruning work you will do in order to maintain a good shape. Unless you are removing large limbs that are diseased avoid any pruning that will result in gaps or leave the plant looking one sided or unbalanced.

A basic piece of piece of information while pruning is that the shoot will go in the direction the bud is facing. This can be used in fruit trees, where you want to create a framework of branches with the center of the plant free of growth. Prune to buds that are pointing in any gaps in the framework of the plant.

An interesting fact is that a bud which is highest up from the root of the plant will produce the strongest and most vigorous shoot. The lower down the stem the bud is positioned, the weaker the shoot will be.

Wounding

A wound, like similar to our bodies, may just as easily get pathogens in it. Just as easily as a small cut or a large branch is to be removed. It is inevitable result of pruning, so it is important to minimize the amount of damage you inflict on a plant when you cut it back.

Avoid making pruning cuts to young shoots during period of severe cold. The sap flowing can free and damage the end of the shoot. Some plants can "bleed" profusely in spring when the sap is rising and should therefore be pruned in late winter.

Always use sharp clean equipment when making a cut. A blunt tool will result in torn bark or wounds with ragged edges. If using a saw, smooth the surface of the wound and the rim of the bark with a sharp knife. This will greatly speed up the healing process with a callus quickly covering the cut to reduce the risk of disease. Slope the cut to allow water to run off. If the cut is above a bud, slope it away from the bud rather than towards it. Ideally you should make a pruning cut 2-3mm above the bud.

Young branches have visible buds and old wood will have dormant buds that are not noticeable. Cutting large branches to a suitable height for rejuvenation will, with many shrubs trigger the dormant buds to produce shoots. Once the shoots appear the stump should be cut back to the new shoots with a sloping cut.

Removing Large Branches

When removing large main or side branches of trees or shrubs you should make the cut just above a healthy, lower side branch that is growing in the required direction. With the cut in this direction the plant will produce lots of growth cells to seal the wound quickly. If you leave stumps that refuse to produce new growths they will decay and might become diseased.

Proper techniques and cuts should be taken when cutting large side branches away. Using a under cut and over cut about 6 inches from the main branch will reduce the chances of the bark tearing and pulling. The final cut can be made holding the final piece with one hand while you saw with the other. Cleaning up the edges with a knife after the final cut is done.

Narrow-Angled Forks

With many trees such as birch, maple, and beech, a narrow angle between two branches is an accident waiting to happen. It can occur at any time but often happens in the early stages of a trees life, when two stems vie to become a leader. If both are allowed to grow there can become a weakness where they come together, due to the double layer of bark that grows in the small space between them. Unlike wood, the mas of bark has no strength. In high winds or a storm is may cause the branches to split away which might result in serious damage where it falls.

Check young plants for the forks. Select the weaker one or the one growing at an angle to be removed. Where the two branches are very thin, leave a bit of holding wood till the remaining leader can thicken. Removing it at a later point.

Ring-Barking

This practice is a peculiar form of pruning which slows down the flow of water and nutrients to the head of the plant. It is a useful method when trying to keep the tree within the bounds of a small garden. Reducing the excess vigour in trees such as apples and pears will also encourage flowers and fruit to form. Cut a 5mm wide band half way around the main trunk about 30-45cm above ground level. The sap has to flow through the gaps which reduces the volume and slows it down. Do not make a continuous band around the trunk or the sap will be cut off and the tree can die altogether.

Nipping, Snipping, Pulling, Dead-heading, Disbudding

Some perennial plants die down in the winter, so pruning is simple by cutting or pulling off all the dead stems at ground level.

Using your fingers to nip or pinch out the growing tip of a shoot will encourage it to produce side shoots. It can be therapeutic for the gardener, but the overall goal is the essential bits for the growth of plants.

Disbudding is carried out on dahlias and chrysanthemums by reducing the number of buds on each stem. Once removed all the plant's energy is then concentrated in the remaining buds, thus increasing the size of the flowers.

Deadheading is the term used to describe the removal of the spent flowers before all of the plant's energy is devoted to producing seed. It will vastly speed up the appearance on the next flush of flowers.

Pruning Shrubs

Where neither edible nor attractive fruit, berries or seed heads follow the flowers, deadheading to remove the old flowers will leave the plant looking tidy. Long shoots that are spoiling the overall shape of the plant may be shortened back in spring to the same length as the majority. And that is pretty much all you will ever have to do, these are low maintenance shrubs that are a real boon when gardening time is precious.

Other shrubs will deteriorate quickly if they are not pruned atleast once per year. In spring or after flowering shorten all the one year old shoots back to within 2-4cm of the old hardwood. The older wood will not produce new shoots, so the new growths have to come from the younger stumps.

Plants such as dogwood can be cut back hard to just stumps with a few buds. The best approach with shrubs is to completely remove some old branches right at the base each year late in spring. Strong flowering shoots are then produced from ground level rather than from halfway up the old branches and the clutter of congested branches is thinned out. It is ideal to thin out all the weak shoots at the best for better growth.

If you have low hanging branches close to the ground, don't rush to remove these. Many of the popular garden shrubs can propagate by layering the shoots where they touch the soil. Some shrubs, such as dogwood, will root everywhere a branch rests on the ground, and if not thinned out, will become a thicket of branches.

Spring Pruning

Some shrubs that flower in summer time are pruned before the new growth really starts. Many of them have enormous amounts of growth after they are pruned and before the flowering starts.

With plants such as forsythia, the flowering comes on the young growth of the previous summer or autumn, pruning should be carried out after the flowering.

It is recommended to leave tender shrubs until late spring when all the risk of frost is over. Pruning encourages new shoots to grow, and these are the most prone to front damage. Pruning in late winter encourages early growths that may be damaged by frosts.

A hard pruning can be done on large overgrown shrubs where the flowers at the top of the plant are out of sight. They can be rejuvenated by cutting all the main branches to knee height.

Climbing shrubs

Where climbers are grown as wall plants it may be necessary to curtail their growth to keep them within their allocated space. Old, bare, and not flowering stems need to be cut out at ground level to reduce congestion and encourage strong new shoots from the base of the plant. If the climbers are a tangled mass prune them to separate them leaving the leaves to wither. At that stage the stems can be clearly identified and removed.

Summary

All throughout spring I will be sharing information related to landscaping, lawns, arboricultural topics to compile a summarized view on the work we do at Kephas Landscaping. Alberta is a unique landscape and it is always a thrill once spring emerges.