Colorado experiences some severe weather from rain and floods to windstorms and even landslides. That makes for quite a few challenges when planting trees and shrubs. We need to pick the exact right tree or shrub and avoid those that either don’t grow or grow too much, taking over the landscape and causing damage.
We’ve prepared lists of recommended trees and shrubs as well as what to avoid. It’s also important to stay clear of poisonous plants.
Recommended Trees and Shrubs
Recommended trees for planting in Colorado include English oak, hackberry, bur oak, honeylocust, Kentucky coffeetree, American elm, Shumard oak, Norway maple, Ohio buckeye, amur cork tree, Canada red cherry, golden raintree, canyon maple, crabapple species, and redbud.
The best shrubs and bushes to consider for your yard include oakleaf hydrangea, spiraea thunbergii, purple smoke bushes, emerald gaiety, dogwood, Japanese skimmias, blue star juniper, Nanking cherry, Panchito manzanita, Pawnee buttes sand cherry, and dwarf globe blue spruce.
Trees to Avoid
Trees to avoid are primarily fast growing with invasive root systems. The fast growth can overwhelm other trees by blocking sunlight. The invasive roots can cause damage to your home’s foundation, sidewalks, driveway, and patio.
- Quaking aspen. This tree looks great in nature, but it propagates by sending out roots that then sprout into still more trees. That’s the definition of an invasive root structure.
- Siberian elm. These trees take well to most any soil type and condition. But they also send out lots of seeds that can quickly overwhelm your lawn. Their branches are also brittle and prone to breaking in wind and snowstorms.
- Russian olive. This is also listed as a noxious weed due to its ability to send seeds far and wide, establishing growth quickly, and outcompeting native plants.
- Salt cedar or tamarisk. This invasive tree hoards water, light, and nutrients, plus it secretes large amounts of salt. It also attracts beetles that have become their own invasive problem. This isn’t something you want in your yard.
- Tree of heaven. This tree generates a very large number of seeds throughout the growing season, giving you lots of opportunities for raking. Its roots, leaves, and bark release an allelopathic chemical that prevents or kills plants growing nearby.
- Ash. This beautiful and quick-growing tree is under attack by the lethal emerald ash borer insect. It threatens to wipe out the ash trees. Don’t plant new ones.
- Austrees. This is a hybrid willow with highly invasive root systems that can clog sewer lines and septic systems and do a number on your foundation.
- Black walnut. This tree is subject to a fungus called thousand cankers disease. They also secrete a growth-inhibiting toxin that can ruin your flowers and vegetable garden.
- Silver maple. This tree is fast-growing but has shallow roots that make it a hazard in severe weather. Those same roots can cause cracking and heaving of concrete driveways and sidewalks. They don’t do well around foundations.
- Cottonwood. These trees need lots of water and send out lots of shallow roots in search of water. That means they can find foundations and do significant damage.
Shrubs to Avoid
These bushes are extremely invasive. They take over everything around them. Avoid them entirely.
- Shrub honeysuckle. This bush can grow just about anywhere under sun, shade, wet, or dry. Of course, it can also spread anywhere and push out your other plants.
- Japanese barberry. This plant is drought and shade-tolerant as well as deer-resistant. However, it’s a breeding ground for black-legged ticks that can carry Lyme disease. It is also invasive and covered in sharp barbs.
- Burning bush. These shrubs create dense thickets, crowding out smaller plants.
- Common buckthorn. It can grow 20 to 25 feet tall, forming an impenetrable layer of vegetation. This shades out all other plants and contributes to erosion.
Colorado Noxious Weeds
Colorado State University has identified approximately one million acres of noxious weeds in our state. Not only that, but they cost more than $10 million annually in lost productivity. The trick is to make sure your lawn doesn’t contribute to this disaster.
You’ll need to watch for leafy spurge, spotted knapweed, diffuse knapweed, Russian knapweed, Canada thistle, musk thistle, Dalmatian toadflax, yellow toadflax, field bindweed, and purple loosestrife.
Avoid these poisonous plants in your yard. If you find them, carefully dig them up and dispose of them.
- Poison ivy. Birds eat the berries and then spread the seeds, so you may find this plant in your yard. The oil from the plant causes severe allergic reactions. It can be extremely dangerous if it gets into your eyes or lungs.
- Red baneberry. The berries cause nausea, dizziness, increased pulse, and severe gastrointestinal problems.
- Myrtle spurge. This plant has a toxic sap that causes severe skin irritation including blisters. If ingested, it causes nausea, vomiting, and diarrhea.
- Death camas. This can be confused with wild edible onion. This one causes slowed heart rate and diarrhea.
- African rue. It has four toxic alkaloids that are extremely poisonous to livestock and humans.
This list is just a starting point for a large number of plants in our area that are poisonous.
Mulch adds nutrients, insulates plant roots, and decorates your plantings. However, it also collects excess moisture, providing a breeding ground for termites and other pests.
If mulch is piled up around your foundation, it can lead to moisture in your basement or crawl space. It’s best to use a hyper-absorbent mulch that helps your plants and keeps water away from your foundation.
Where to Plant — Sunlight and Shade
It’s wise to review each tree and plant to determine the type of sunlight they need before you plant them. You’ll also need to determine the spacing requirements to prevent them from running into and over each other.
It’s also very important to make sure plants are far enough away from your foundation that their roots are not causing damage. Roots can remove moisture from around the foundation during dry spells and can also place stress on your home’s basement or crawl space walls.
Protect Your Home’s Foundation
Careful water management is the key to protecting your home’s foundation. Landscape grading must allow the water to flow away from your home. Gutters and downspouts should also route water off the roof and away from the foundation.
An irrigation system can be helpful in maintaining just the right balance of moisture in the soil around your foundation as well as for your plants. A smart sensor can adjust the amount of water based on the rainfall or lack of rainfall.
If you’re experiencing a damp basement, consider waterproofing that includes installing a drainage system and sump pump with a backup battery to collect and remove leaks before they become problems.
We recommend you consult the professionals at Complete Basement Systems for a free inspection and repair estimate to identify any issues with your basement or crawl space, as well as the surrounding landscape that needs attention.