Hi, I’m planning to plant an evergreen hedge along a tall wall to block some unwanted view from behind the wall. I need trees that can grow 15-20 metres tall and stay as narrow as possible (no more than 3 metres). I don’t mind having wider lower branches while the trees are still young. However, due to the shaded spot I believe the lower branches will just naturally die over time, which is actually preferred.
I have narrowed down my selection to a few: Balsam Fir, Norway Spruce, Hoopsi Blue Colorado Spruce, Iseli Columnar Spruce, Blue Weeping Nootka. I don’t know which ones of them grow faster than the others, and which ones can tolerate more shade. Looking for some help to choose one or two that’s most suitable for the purpose.
Thanks a lot!
Hello – You have some interesting trees so far in your selections but I’m not sure that any of them meet your requirements and will thrive in your growing conditions. The first consideration should be the site conditions in which you will be growing your evergreen hedge. You note that the site is a ‘shaded spot’. Most of your selections require full sun which is defined as 5-6 hours of direct sunlight daily. Balsam fir (Abies balsamea) and the Blue Weeping Nootka falsecypress (Chamaecyparis nootkatensis ‘Pendula’) will tolerate part shade – defined as 3-4 hours of sunlight daily. Growing any of your selections in less than their required light conditions will result in bare branches. As a rule of thumb, shade tolerant evergreen species include most Fir (Abies), Yew (Taxus), Arborvitae (Thuja) and Hemlock (Tsuga).
In terms of growth rate, only the Norway Spruce (Picea abies) is fast growing putting on 62 cm or greater of growth annually. The Blue Weeping Nootka has a medium growth rate – 33 to 61 cm of growth annually. The rest are all slow growing with 32 centimetres or less of annual growth. Based on the criteria of light requirements and growth rate, the Blue Weeping Nootka looks to be the best choice. However, this tree has a mature height of 8 metres and width of 4 metres so not the overall form you are looking for. The Blue Weeping Nootka is described as having a low canopy meaning it has a wide, low base created by its weeping nature. It is a striking tree but usually used as a specimen plant to show off it’s interesting shape. Looking at the form of all of your selections, they have a pyramidal form rather than the columnar form suggested by the dimensions you specified.
The Eastern Hemlock (Tsuga canadensis) may be a species to consider. As noted above, the hemlocks are generally shade tolerant and the Eastern Hemlock has a medium growth rate. At maturity it is not quite as tall as the Balsam Fir and has a similar pyramidal form. As an added benefit and again similar to the Balsam Fir, Eastern Hemlock is a North American native tree.
To further fine tune your selections first be clear on your site conditions. Is this a part shade (3-4 hours of sunlight) area? Soil conditions may also be a consideration. Some species will tolerate a wide range of soil conditions while others have specific requirements. Balsam Fir for example, prefers a more acidic soil. Do you have some flexibility in the dimensions you specified? Would the pyramidal form work for you? Is the height you’ve specified a fixed requirement – your selections show a lot of variability in height?
A resource I found very helpful in learning about your tree selections is the web site of the Morton Arboretum (which is located just west of Chicago). They have an extensive database on different species, their landscape use, the site requirements for each species and a list of cultivars of the species. This web site may be helpful to learn more about your selections. I’ve included the link below.