Malus dolgo (Dolgo crabapple)
Malus adstringens cvs. (Rosybloom crabapples)
Malus x hybrids (Other flowering crabapples)
Crabapples are among the most common residential landscape trees in Alberta, and for good reason. Their brief floral display in early June is worth the wait, and many people have told me they keep the trees specifically for that one week of blossoms. Crabapples make an exceptional ornamental specimen tree in front and back yard gardens, and are particularly useful in newer neighbourhoods that have smaller front yards. Some varieties are grown for their purple foliage and highly ornamental fruit in summer.
I like these trees because they’re malleable. They easily tolerate a range of pruning and shaping styles. If properly trained from a young age, crabapples have few problems, with the exception of the potential for fireblight in certain varieties.
Full sun but preferably not south-facing where they get full exposure all day. Young, thin-barked trunks have a tendency to develop sun-scorch. I place them where I know the trunk will get either filtered sun or a bit of shade from a neighbouring plant.
Time to Prune
Dormancy, from late Fall to mid-April is best. I only prune apples in summer to repair broken branches.
There are many ways to prune a crabapple, depending on the location of the tree, and whether or not a formal shape or natural form is preferred. Since the majority of people I speak to want “low-maintenance,” I will describe the basic maintenance for a natural form.
I rarely get the call from people to prune their crabapple trees until they’ve been in the ground for 10-15 years, minimum. By then, they have developed very poor structure, and radical pruning is sometimes necessary. Even then, I’m sometimes unable to restore a good structure without seriously disfiguring the crown. So on a mature tree that hasn’t had proper maintenance in the past, you simply remove dead, diseased, and damaged wood, remove redundant or severely crossing and rubbing branches, and manage the overall shape of the tree by pruning back over-extended branches from time to time to make things appear balanced. As with most trees, the goal of pruning should be to have a flow of branches “up and out” from the main trunk.
The most common thing I see with crabapples is poor structure, where many or all the of main branches originate from the same point on the trunk. This can be corrected at planting, either by proper structural pruning, or by simply selecting a better plant from the garden centre. Structural pruning should begin at planting and continue for at least the first 5 years of growth.
If you have an opportunity to start training a natural-form crapapple from planting, do the following: Most importantly, select a tree that has a single-stem trunk (called a central leader standard), with well spaced lateral branches. If there are two or more main branches originating from one point, reject the tree. Plant the tree in spot in the yard where it will fit in its mature form without clearance pruning. Most crabapples mature at about 15-20′ height and width. That means don’t plant the tree any closer to than 8-10′ in all directions from the fence, house, or garage. Trust me on this and you’ll thank me later. When a tree has its space, it is a lot easier to maintain and looks a lot better without regular intervention from the restless husband or the over-zealous neighbour. In the first year, you may not have to make any cuts if you select a good tree. In the second and subsequent years, remove dead, diseased, or broken limbs, and remove branches that are growing back toward the trunk, and branches that are crossing and rubbing, and might appear to be a problem as the tree matures. One common mistake people make is that they prune off every bud on every branch as high as they can reach. Buds and small twigs and spurs are important. They shade the stems and allow the lower leaves to complete the form of the tree, making the canopy appear full.
Crabapples are well-suited to shaping and crown reduction, providing that cuts are not made into wood older than one or two years. As with all trees and shrubs that are cut from the “top-down,” however, be warned that formally shaping an crabapple tree is a high-maintenance procedure that requires skill and experience. Improperly pruned, you will be left with a topped tree that will quickly (a year or two) turn into a mess that will require restoration pruning in order to resolve. Unless you are an experienced pruner and appreciate high-maintenance, avoid crown reduction and shaping. A shaped apple in the Red Deer area will require annual re-shaping to look its best. In the Calgary area, you could probably get by with 2 or 3 years between prunings.
In a later post, I will thoroughly explain the process of properly shaping an apple or crabapple tree.
(c) 2015 Shane LePage, Wild Rose Garden & Tree Service Inc., Red Deer, AB