I have a couple of questions for you accompanied by a few photographs about a yellow poplar and a maple in my yard.
Q: The first question is about a yellow poplar that was here when we moved in about three years ago. It was in need of a trimming, so I did so that winter, especially to remove a lower branch that was out of place. I know certain varieties of the species tend to grow straight up and produce a pyramidal crown later, but this tree seems pretty mature to have not done that yet. I’m wondering, is there any special pruning or anything I can do to help it spread out and start producing shade? The tree is about 20-25 feet and about 6-7 inches in diameter at the trunk.
A: Looking at the image of the yellow poplar, Liriodendron tulipifera, I immediately wondered if you had purchased a columnar cultivar of this tree. Checking the Manual of Woody Landscape Plants, by Michael Dirr, I noticed a yellow poplar cultivar named ‘Fastigiatum’ that was developed at the Arnold Arboretum near Boston. “Narrow, with upright lateral branches that almost parallel the central leader…grows 50 to 60’ high by 15 to 20’ (25’) wide; a handsome, useful form; larger plants become fat at the base and lose some of the fastigiated character; put into commerce by Monrovia Nursery; has found a home in commerce.” If this indeed a ‘Fastigiatum’ cultivar of the yellow poplar no amount of pruning with alter the shape & form of the tree’s canopy. Dirr does mention the tree will broaden with time, but I expect the wait will be a long one. Please consider getting another opinion from a local arborist to see if they agree with my assessment. One possible solution is to have an arborist with a tree spade move this columnar yellow poplar to a new location, so that the common form of the tree can be planted on this site to provide full shade.
Q: My second question is about three maples I planted in the fall of 2008. I took the usual care to score the root ball, plant in a large hole, and not plant them too deep, but I’m convinced that in two years, none of them has grown a single inch. They get leaves, but that’s it. My only guess is that the roots can’t grow out into the compacted clay, but I can’t be sure. What can I do to get them growing, and should I do it this fall or wait until spring?
A: Keep in mind that balled & burlapped and potted trees have lost up to 85% of their roots systems. Some studies show it can take up to 5 years for these trees to recover roots lost during the shock of transplanting. I’m pleased to see that you are aware of the whole planting depth issue. In addition to planting depth issue, I like to inspect tree root systems on site at the nursery to check depth within the ball or pot. I’m also checking to make sure there are no stem girdling roots at this time. Take a moment to read through this web site to better understand the issue.
As for your maples, I would dramatically enhance the mulch zone around the trees to enhance their growth. In my opinion, fertilization isn’t the solution to this problem. The mulch will enhance the site conditions and reduce competition.
University of Florida – Landscape Plants – Dr. Ed Gilman Note the links in the research above showing the following mulch best practices: best, recommended, minimum, not recommended, mulch precautions
Faster Growing Trees with Proper Mulch
Proper mulching will help the trees grow faster, decrease competition with weeds & grasses, keep lawn mowers at bay, and improve the overall health & condition of your maple trees.
If have any Tree Care questions please contact info[at]arborday.org and we will be happy to answer them.