To have beautiful crabapple trees in bloom in spring, don't overlook the importance of pruning during the dormant season. Discover the advice of the Japanese Garden's specialized horticulturist.
Crabapple trees vs. cherry trees in the Japanese Garden
Owing to the lack of hardiness of cherry trees from Japan like Prunus serrulata and Prunus subhirtella we use crabapple trees (Malus) which better tolerate the extreme weather fluctuations that we experience in Montreal during winter. They produce a similar visual effect at the same time of year.
Did you know this: the crabapple is the tree emblem of the city of Montréal.
Pruning during the dormant period
At the Japanese Garden pruning is carried out during the dormant season when there is no longer a risk of severe cold. Generally from the beginning of March until mid-April. We also make sure that pruning is done before bud break (the opening up of buds).
When we prune, we begin by removing suckers and sprouts.
Suckers grow from the tree’s rootstock. If we let them develop, they may form new trunks of a completely different type of tree. This is because the crabapple was grafted onto the rootstock of another variety. Note that the removal of suckers can be done at any time of the year.
Sprouts are branches that grow upward. They may eventually come into competition with the top of the tree. Besides, they produce no blooms, and therefore no fruit.
The next step is to remove all dead and crisscrossing branches.
Once all the above is done, we move on to esthetic pruning. We remove branches or parts of them to reveal the natural beauty that the tree has to offer, making sure that the remaining branches are not crowded together. It’s essential to provide space at the heart of the tree. The spread of diseases like scab and fire blight is more frequent when branches are congested.
We also shorten certain branches in order to guide their growth and keep some of them from competing with the top of the tree.
To encourage abundant blooming and subsequent fruit production, it’s good to know how to distinguish flowering buds from wood buds.
Flowering buds are swollen (round) and perpendicular to the branch, while wood buds are longer, pointed, and usually hug the branch.
Golden rule to respect
The golden rule to respect: Do not prune more than one-third of the living branches.
When pruning, we use appropriate well-sharpened tools disinfected with 70% ethanol or isopropanol, or better still, with the flame of a blowtorch or burner.
This has just been a quick look at what we do in the Japanese Garden when we prune crabapples. It’s imperative that this pruning be conducted every year in a way that ensures balanced development.