Clients are often surprised when they hear that it is common for our designs to include 5 to 7 trees. An urban lot of standard dimension can easily accommodate two large trees (one on the boulevard and one in the back yard, for example) and 5 small to medium trees.
Here are a couple things to think about…
Oaks first – In general always consider an oak if you have a space that can accommodate the size and slower growth rate. Oak is a great tree for our urban forest since it lives long and has less risk of dropping limbs.
Resist maples – The second rule would be to resist going to a maple as your first choice since maples are over planted right now – especially Autumn Blaze.
Weaknesses – Try not to rule trees out for one characteristic – yes gingkos have smelly fruit, yes walnuts make growing things underneath difficult, yes, Kentucky coffee looks forlorn when young, but these trees can have a place in some landscapes.
Large Trees We Like – ‘Majestic Skies” Oak; ‘Jefferson’ Elm; Swamp White Oak, Kentucky Coffee, Catalpa, Hackberry, basswood, River birch.
MEDIUM TREES (25-40):
Medium size trees can be very useful in urban landscapes. They are sometime faster growing trees that live shorter lives but create privacy and are fairly easy to remove in 30-40 years. Also some slower growing trees that work well with other plants in your landscape.
White Bark – Birches and aspen fit in the medium size category. Aspen is a tree that gets lots of foliar diseases and trunk ailments. But planted in groupings can create an instant effect and can be removed easily. Big tooth aspen is a unique native option. Birches are everyone’s favorite but one of the harder trees to get to thrive. They are effected by transplant shock when planted during the hot part of the summer and should generally be babied more than other trees. Plant in groups with dense underplanting to shade their roots.
Slower – We like slower trees. They generally have fewer issues over the life span of the tree and have low maintenance costs. Ironwood (Ostrya virginiana) – Interesting bark, nice golden fall color. Blue beech (Carpinus) – starts as a small tree but gradually grows to medium. Interesting “muscular” bark. Nice purple fall color. Buckeye – would eventually be a large tree but slow growth keeps it to a medium tree for a long time. Huge flower. Gold fall color.
Faster – Amur chokecherry. Great cinnamon-y bark and fast growth rate makes this a good plant for quick privacy. But doesn’t get overly large and will most likely succumb to disease before 40 years. Japanese tree lilac is a hardy plant with good form and nice thick leaf cover.
Open Canopy – Amur maackia – in the pea family, so has fine compound leaves. Really good plant to grow perennials under because of open canopy. Interesting bark and nice flower makes this one of our favorites. Mountain ash – in the rose family so prone to fire blight and other diseases but a really beautiful plant that has a place in the urban forest.
Flowers – Larger crab apples can be a great plant in the medium height range. New crabs have a great range of flower color choices, form (wide or narrow) and some have interesting dark leaf.
SMALL TREES (10-25’):
We use more small trees than any other type. It is not uncommon to use 3 to 5 small trees on a property. Most of these are ecologically “woodland edge” trees – so they work well in yard where there is some sun but not full sun. These are our workhorse trees – there isn’t a great variety but we use these over and over and over.
Serviceberry– Native plant that can be purchased as a small shrub, small tree or multi-stem shrub. Has thin stems that are smooth and gray. Nice small white flowers in spring and will get a little fall color in sun. Generally upright form.
Red Bud – Has heart-shaped leaves. Really unique in that it flowers profusely with pink flowers before the leaves come out and all along the stems. Form is more vase like and spreading.
Nannyberry Viburnum – Upright plant with similar form to serviceberry. Will take part shade but grow slower. Nice white flowers in spring.
Pagoda Dogwood – Has distinct form in that the branches grow horizontal to the ground. Really beautiful tree that gets a disease called “golden canker” that should be cut out when you see it to insure it doesn’t continue to spread.
Crabapples– There are many crabapples and other spring flowerers in the small category. Here are a few: Candymint crabapple; Prairie fire crabapple, Korean sun pear.