Populus x ‘Northwest’ Northwest Poplar
Populus deltoides x Populus x petrowskyana Griffin Poplar
Populus balsamifera ssp. balsamifera Balsam Poplar, Black Poplar, bam tree
Populus balsamifera Paskapoo Paskapoo Poplar
Poplar are very common species in Alberta, due to their high success rate and relatively quick growth. They make excellent shade trees in large yards, acreages, and parks, and are a good choice for shelterbelts. Northwest poplars are frequently found on city boulevards. They are reasonably long lived, and relatively insect- and disease-tolerant.
At one time, Northwest and Griffin poplars were commonly planted in residential areas, and I believe that was a mistake. Obviously a lot of homeowners would agree, because these are one of the most commonly mutilated and/or removed tree species. Northwest poplar limbs get very broad and far-reaching, and heavy limbs often end up over the house and garage. While a well-structured tree can stand against most storms, poplar is by nature a weak tree, and unpredictable in foul weather. It is best to leave this shade areas that can accommodate its height and width.
Some people, particularly some arborists, disagree, and believe that the tree can be contained through regular crown reduction. My argument is that if a tree requires that much maintenance, it probably doesn’t belong in that spot, unless the homeowner has a very large maintenance budget and really likes the species. There are better choices for residential yards in urban areas.
Balsam poplar, commonly referred to as bam tree in rural areas, and black poplar to the lake folk, seems to be a generally hated tree in Alberta. They often grow in mixed stands alongside trembling aspen. Older specimens often develop dead tops. They have a reputation as weak trees prone to failure. The female trees also disperse their seed in clumps of undesirable silky tufts, for a few weeks from late May into June. Balsam poplar are commonly mutilated by homeowners and tree toppers in lakefront communities. They are uncommon in urban yards.
I like balsam poplar in the wild, in parks, and around lakes. It has nice fall colour, attracts nesting birds, and the young saplings are browsed by moose and deer. It has several medicinal qualities. That said, it is not a species I consider for urban plantings, with the exception of the ‘Paskapoo’ poplar, a dwarf variety developed at Bow Point Nursery in Calgary. Paskapoo is an excellent tree for small yards, has large, glossy leaves, nice fall colour, and virtually maintenance-free.
Dormancy is best, from late October to early April. If less than 10% of the live crown is to be removed, anytime is fine.
Mature trees can be pruned every few years to remove dead, diseased, and storm-damaged limbs. Width reduction may be required to decrease the end-weight of long lateral limbs, thus preventing storm damage. As poplars are large trees, professional arborists are normally required to perform the work.
Poplars are host to a number of fungal diseases and the occasional insect problems. Pest control measures are rarely required.
(c) 2016 Shane LePage, Wild Rose Garden & Tree Service Inc., Red Deer, AB