FAQ: Pruning Stems and Branches
FAQ: Pruning Stems and Branches
My caragana/lilac row is getting tall, spindly, and has a lot of dead branches. Can I prune the hedge to the ground and what time should I do it?
- Yes. Pruning of unruly older shelterbelts like caragana and lilac is recommended.
- Most shrubs can be successfully pruned to the ground with a chain saw during the dormant season. This is a severe form of pruning and it should only be done when the shrubs are dormant (no growth or leaves).
- Severe pruning (> 30% of the tree mass) during the growing season is not recommended – at this time the trees are actively growing, and severe pruning will put excessive stress on the tree and may lead to serious disease and insect problems or even death.
- When pruning, it is recommended that the cut be made as close to the ground as possible, otherwise, if it is cut any higher, the shrub will continue growth from the height where the cut was made and may end up with a “witches broom” effect.
- By cutting close to the ground, the row will regenerate right from the base with new shoots and will look much neater and more uniform.
- Since the plants in this row have a large, well established root system, they will regenerate quickly and may put on 1 to 1.5 metres growth in one season.
I have some poplars that are starting to show die-back at the top. Should I top/cut them back to rejuvenate them?
- No! This is a practice called pollarding (topping) and it is not recommended for mature, large trees.
- In pollarding, the tree stem is cut back to healthy wood well below the dead area. Pollarding will encourage succulent growth, called watersprouts, from the cut area.
- This undesirable growth will look like a ‘mushroom’ coming out of the top part of the tree at the cut. These water sprouts are spindly and unhealthy and the energy required for this type of growth will weaken the tree – thereby increasing the chances of insect and disease attacks.
- This practice will lead to the eventual decline of the tree. Pollarding is costly and does not increase the lifespan of the tree.
- Poplars are short lived in dry areas. In these locations, poplar may reach the end of their normal lifespan, and start showing signs of decline (top die-back), much quicker than in more favorable areas.
- In most cases, no. Recommended wound dressings can be applied when the diameter of the cut is more than 15 or 20 cm.
- When using wound dressings only use those that are made for and recommended for trees.
- Do not use paint or petroleum products as they will damage the tree. Either use the proper dressing or use nothing at all.
- Studies have indicated that most untreated wounds (if the cuts are made correctly and close to the stem or trunk (as recommended) will heal more quickly than those that have been treated with a dressing.
Some of my spruce/pine trees have double leaders. How can I prune my trees so they only have one leader?
- Sometimes a conifer tree may form two (or more) leaders naturally or it may experience injury which could result in multiple leaders. Pruning of secondary leaders ensures that the tree continues growth in an upright manner and keeps the form that the tree should normally have.
- It is better if this can be detected and corrected when the tree is still young.
- The first step is to determine which leader is the most aggressive, healthiest and the straightest. This will make the best leader. The remaining inferior leaders should be pruned so that half is taken off in early June once they have extended to their maximum length.
- The main leader will continue growth ahead of the others and will eventually take over as the dominant leader. The others will eventually become laterals or shorter leaders and will not overtake the main leader.
My green ash/poplar/maple has formed two stems of equal size. Should I prune one off? How and when should I do it?
- Sometimes seedlings form double leaders from the base of the tree. Although it will not necessarily affect the health of the tree, it is best to correct this problem early when the tree is still young so that the tree forms a single, strong stem.
- By forming a single stem right from the beginning, it will prevent splitting of the stems later in the trees’ life.
- First, choose the most aggressive or the straightest stem. If they are both the same, it does not matter which one is removed.
- Prune off one of the stems close to the base of the tree when the tree is dormant.
- If pruned when the tree is actively growing, there is more of a chance that there will be many small shoots/water sprouts originating at the base which will have to be constantly pruned off year after year.
- It is recommended that these shoots be removed to ensure that the tree keeps its true form as a single stem tree.
- The best time to prune deciduous trees is in the dormant season from October to March (depending on the weather in that particular year). They can be pruned any time from when their leaves drop in the fall right up until they break bud in the spring.
- EXCEPTION: Maple and Birch trees should be pruned when they are actively growing (leaves on). If they are pruned in the dormant season, they will bleed from the wounds in early spring and although this may not kill the tree, it weakens it and leaves the wounds open to diseases and insects once the sap starts to flow. When pruning these species it is also preferable to prune when it is cooler rather than on very hot days and earlier in spring (May-June) rather than in mid-summer.
- Pruning of diseased, dead or structurally unsound branches can be done at any time of the year.
- ALWAYS make sure that pruning tools are well maintained, sharp and disinfected between cuts to make sure diseases are not transported from tree to tree.
- Disinfect tools with alcohol, a 10% bleach solution or any other recommended disinfectant. Keep in mind that some disinfectants may cause premature rusting of pruning tools.
- Pruning of Scots pine, Colorado spruce, and white spruce to increase their density should be done in spring (usually in early June) after the candles (new growth) have extended to their maximum length but before they actually open.
- To increase the density, snip half of the candles’ length off wherever you want to increase the density of the tree. If you want to increase the whole tree’s density, prune candles all the way around the tree – in this case, they can be sheared with hedge trimmers being careful not to take too much off the tips of the branches.
- If you just want to thicken up one area or a hole in the crown where a branch is missing, just prune candles in that area. At the point where you cut each candle, three or four new buds will form and develop throughout the growing season (June to August).
- The following spring, the newly formed buds will open and since there are more buds at that point, they will fill in that area.
- Conifers cannot be pruned like deciduous trees.
- Willows have extremely high moisture requirements. In years of low rainfall, extended drought, or on coarse, gravely soils, willows will suffer and possibly die.
- They may experience top die-back if they are not grown under recommended conditions. Check for insect, disease or chemical drift problems.
- cut dead branches off
- water well, and
- keep weeds and grass from between the trees to decrease competition for moisture.
- Only plant willows into areas that will receive high rainfall or into areas where moisture is plentiful.
- Willows can withstand some flooding (3-4 weeks in the spring).