As an arborist I am often faced with the tragic duty of removing lovely healthy trees that are in bad locations due to poor landscape planning. Most often a tree was planted close to a structure when it was small, without consideration as to how large it would become as it matured. There are many factors to consider when choosing your tree so that both you and the tree can coexist happily.
Size is perhaps the most important consideration when your planting site has limited space. Trees start out small and patience can be difficult to come by as you wait for it to grow and fill in an area the way you want. For a successful, sustainable planting, we must look at the long term goal rather than simply the present. Trees are wonderful; however they will not oblige us with instant gratification. When choosing your tree, find out what it’s mature size is expected to be. Look for variants in shape and size if you have odd shaped areas to work with. For instance there are trees that get tall, but have a narrow growth habit. this is referred to as columnar (white oak comes in a variety that is a popular local choice for this growth habit) . There are trees whose canopies grow as wide or wider in width than in height (for instance, Norway maples). If you are planting multiple trees, or already have existing trees, the spacing between them is important. Large trees need a lot of space. If you have a large area to fill, give each large tree plenty of room in respect to it’s projected mature size. It will feel empty for a while, but your trees will end up far healthier if they are not competing with one another for light, water and soil. When you choose your tree, choose it with that mature size and shape in mind.
Roots are often left unconsidered when anticipating the size of a mature tree. In fact, the roots of a tree account for a very large portion of it’s whole; often a third or more of it’s total volume. When it comes to roots keep in mind what will be surrounding the tree on the ground. Is there enough permeable surface so that the roots will receive enough water and oxygen? Is there a sidewalk or driveway nearby that might get lifted if it’s a larger tree; or a foundation that might be damaged? The unseen portion of the tree is no less important than the rest of the tree.
Climate is another important factor in tree selection. We live in what is usually (despite this wonderfully wet spring) a fairly arid region. Beyond the climate, what type of area will your tree be planted in? There are many options on the spectrum between a xeriscaped front yard and an English garden. Find out if your tree needs a lot of water, or if it is drought tolerant. Depending on where in Colorado Springs you live, you should be in a hardiness zone of 4 or 5 according to the USDA hardiness zone map. This refers to the region’s average temperature fluctuations. Know how hardy your tree is before you buy.
Consider disease resistance of different species and sub-species. Is the kind of tree you want prone to certain sicknesses or pests? For instance, fire blight is a common problem amongst fruit trees in our area. If you’re looking at getting a crabapple tree, certain types such as the ‘dolgo’ variety are more resistant to fire blight than others. This information can be found via online research, or just by calling a local tree nursery.
Contemplate the trees surroundings in terms of what other plants are there. If you’re planting flowers or shrubs, do they need full sun? Partial shade? Different trees create different types of shade. Norway maples cause dense shade, while honeylocusts cast a lighter, dappled shade. Will the tree’s roots be in competition with grass? If so, an irrigation system that waters the grass is often insufficient to support a tree (in this case it is often best for the tree to receive supplemental watering at its dripline). Grass can present another dilemma if you plant certain evergreen trees. Many pine and spruce trees cause the surrounding soil to become acidic. This is good for these trees, but many kinds of grasses cannot tolerate acidity. This type of holistic planning can be complicated and time-consuming, but you will be more likely to achieve harmonious coexistence in your landscape if you plan well.
Finally, according to your design, do you want deciduous trees (trees that shed their leaves during winter) or evergreen trees (trees which retain their leaves and/or needles during winter)? Many deciduous trees including green ash have irregularly shaped canopies when they reach maturity; some have more formal appearance, such as columnar varieties. Many evergreen trees like Colorado blue spruce have a more defined single dominant lead, resulting in a more pyramidal shape; while others, for instance ponderosa pine develop irregular canopies as they age.
Tree selection is very important, regardless of whether you just want a few trees in your yard or you want to create a beautiful landscape design. If you choose your trees carefully, you can reduce future complications immensely.