I want to turn two viburnums that I am growing into trees. They are Viburnum prunifolium, called blackhaw viburnums, and they are naturally multi stemmed, upright, vase shaped shrubs. They can become quite large.
Here is one of the blackhaws, the year after I planted it, still a small and tidy shrub.
With pruning they can be shaped into trees that look similar to hawthorns, with a rigid form, and a lot of character. That's what I want.
However, I haven't got a clue what I am doing.
You can see from last summer's picture that I have already taken off quite a few lower branches.
Viburnum prunifolium is a very densely branched, twiggy shrub and it suckers. The key is to prune it when young, and in the three short years of this viburnum's life in my garden I have taken off over a third of the branches each year. I also cut back the suckers that form around the base.
The branching of blackhaw viburnum can only be described as congested.
This winter I went at it again. That angled crossing branch to the left looked kind of interesting, but to get a vase shaped tree form, I thought it should come off.
Here it is after pruning. I took off the angled stem and I took off another branch on the upper right too.
By taking off the funny branch I may have removed some of the character I wanted, but I do have an idea in mind. Here is what I am going for. This picture is from Learn2Grow:
Or this, from Willow Landscape Design, which says blackhaw is semi evergreen (it's not for me), and that the leaves are purplish (mine have no purple tinge) -- but what a lovely shape and form:
Like all viburnums, blackhaw has pretty white flowers in spring, interesting berries, and decent fall color. Mine is planted right where I can see it in front of the garden, and although it is still young, it flowered finally last year, with lacy white flat-topped blooms the last week in April.
I have another one that I grew from a six inch seedling planted in 2006. It also needs pruning to become the tree I want it to be. It is smack up against the house, so it will need to be shaped for size as well. I know the stubby lower left branch has to come off, but what else should I be doing with this one?
Does the vertical upright branch in the dead center need to be there? Would it look more open and spreading if I took that out?
The good news is that Viburnum prunifolium is so dense that I can't really make a mistake by cutting off the wrong branches. It just grows more, sometimes oddly and in weird directions, but that's the character of this angled, stiff little hawthorn look-alike.
Still, I'd like to influence these to grow into real trees with a nice shape. Suggestions?