As spring arrives, our local nurseries and garden centers will be filling up, especially with the plants, trees, and shrubs that can go in early when temperatures are still a bit erratic. Optimal periods for planting trees in Colorado are spring (March 15 to June 15) and fall (Sept. 1 to Oct. 15). If you are considering adding a new tree to your yard this year, now is the perfect time to do a little research, perhaps just a touch of soul-searching, and decide on what species is the best fit for your landscape.

While it’s true that you can pop just about anything into the ground, whether or not it will thrive or even survive, is a different story entirely. As you begin to think about what kind of tree is right for you, you’ll have several factors to consider.

That brings us to irrigation. What kind of irrigation will be available for your new tree? Automatic sprinkler system, drip irrigation, or will you be hand-watering? As a general survival rule, apply 10 gallons of water for each diameter inch of the tree. For example, a two-inch diameter tree needs 20 gallons per watering. To get your tree’s diameter, go 4.5 feet up the tree and measure around its trunk to get the circumference. Then take your circumference and divide by 3.14.

Trees generally take one year to establish for each inch of trunk diameter. Establishment is achieved when a tree’s root system is well-developed, and it has gotten to the point where it can handle normal stressors without its health suffering or going into decline.

• Growth rate
• Mature size
• Form
• Hardiness ability of a plant to survive low temperatures
• Heat tolerance and drought tolerance
• Pest resistance
• Maintenance issues
• Native versus nonnative species

How to Plant a Tree (Colorado State Forest Service and CSU):

• Dig a hole 2-3 times the diameter of the root ball of the tree being planted and no deeper than the root ball. Use a shovel to measure the depth of your planting hole. When planted, the top of the root ball should be slightly above ground level. The root collar (flare) must be visible 1 inch above final grade after planting; trees planted too deep will drown.
• For balled-and-burlaped trees, cut away the bottom portion of the wire basket. Slowly place the tree in the premeasured hole, being careful not to fracture the root ball. Remove the rest of the wire basket. Remove any remaining wire and twine, then peel back and remove as much of the burlap as possible.
• For plastic container trees, carefully remove the tree, not pulling on the trunk as much as possible. Take a sanitized saw and shave off the outer ½ inch of roots around the entire root ball. This removes girdling roots and ensures outward growth rather than circling growth which results in tree decline and issues. This method has proven to be more effective than just cutting roots with a boxcutter or knife and is well worth the effort.
• Set the root ball on solid ground in the hole and not on loose backfill; this eliminates settling.
• After the root ball is in the hole, check to confirm that the root flare (the flare where the trunk meets the root) is visible. You may have to pull back some of the dirt from the root ball.
• Backfill the hole with the original soil. Adding peat moss, manure or fertilizer to the soil in the planting hole is not necessary and not recommended. Too much added nutrients can cause a “potted tree” effect and restrict root growth.
• Place mulch 3-4 inches deep and at least as wide as the planting hole, but do not mulch within 3-6 inches from the trunk of the tree. This will protect roots, hold soil moisture, reduce weed growth and provide a protective strip to eliminate mechanical damage from lawnmowers and weed-eaters. Do not use plastic or landscape fabric under the mulch and do not bury the root flare. Keep grass and weeds out of mulched areas as they compete for the same water and nutrient resources as the new tree.
• If the tree will be in an extremely windy area, staking may be necessary, but most do not require or benefit from staking. The main tree stem must be able to sway. If it is too rigid, root and stem growth will be adversely affected.
• Use wide canvas straps with grommets to tie trees to stakes on the lower portion of the trunk. Do not use wire, string, rope or rubber hose around a tree. These structures can girdle or “strangle” a growing tree.
• Remove stakes and straps after no longer than 1 year.

*Note that the straps in the illustration should be much lower on the trunk.

If you would like to learn more, search online for the following resources listed below:

• 2024 Front Range Tree Recommendation List: Comprehensive list of trees that perform well in our region.
• Native Trees for Colorado Landscapes – Fact Sheet #7.421
• Trees and Shrubs for Mountain Areas – Fact Sheet #7.423
• Evergreen Trees for Colorado Landscapes – Planttalk #1722