This year marks the 150th anniversary of Arbor Day, when the residents of Nebraska planted more than a million trees on April 10, 1872, to celebrate the first tree planter’s holiday.
“Colorado’s neighbors to the northeast struck upon a wonderful idea back in 1872 and the tradition of planting trees to celebrate Arbor Day continues to this day,” said Dana Coelho, Urban and Community Forestry Program Manager for the Colorado State Forest Service. “In Colorado, spring is an ideal time to plant trees, so many communities across our state will celebrate Arbor Day by planting trees and improving their urban forests. The trees they plant today will beautify and benefit those communities for years to come.”
With Colorado Arbor Day this Friday, April 15 and National Arbor Day on Friday, April 29, the CSFS is encouraging Colorado residents to plant and celebrate trees where they live, work, learn and play.
“See what opportunities exist to join Arbor Day celebrations in your community or plant a tree on your own property and bring more color, beauty and wildlife habitat to your home,” Coelho said. “If the ground is thawed and the temperatures are warm where you live, take advantage of this ideal time of year to plant trees, when they have the best chance of getting established and then thriving.”
Aside from planting at this great time of year, residents of Colorado should be sure they are planting the right tree species for the right location. Trees stand a much better chance of survival when the location, topography, climate, soil and tree’s eventual height and canopy spread are considered in advance. In addition, Coloradans should select trees adapted to the environmental conditions where they live, so newly planted trees are tolerant to drought, extreme temperatures and other factors.
“Careful planning is necessary when selecting a tree to plant,” Coelho said. “Trees are a long-term investment; many trees will outlive the person who planted them.”
The following tips are for trees suited for communities and urban settings. They apply to large container or balled-and-burlap trees. For tips on planting seedling trees suited for backcountry forests, please visit the CSFS Seedling Tree Nursery.
Also, remember to call 811 a few business days before digging to request the approximate location of buried utilities so you don’t unintentionally dig into an underground utility line.
- 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-burlap trees, remove the bottom portion of the wire basket. Slowly place the tree in the pre-measured 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 large container trees, completely remove the container. It is important to remove the entire wire basket or container, as these materials can damage root development.
- Set the root ball on solid ground in the hole and not on loose backfill; this minimizes settling.
- After the root ball is in the hole, check to confirm that the root flare (where the trunk meets the roots) 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 organic mulch such as bark or chipped trees 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. Porous landscape cloth may be placed between the soil and the mulch, but do not use plastic 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 necessary, stake the tree to keep the root ball from shifting in strong winds. The main tree stem must be able to sway. If it is too rigid, root and stem growth will be adversely affected.
- Use wide straps to tie trees to stakes. 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 roots are established, usually after one or two growing seasons.
- Keep soil moist but not saturated. Irrigation is necessary, especially during the heat of summer (water in the early morning or at dusk) and in dry winters (take care not to freeze your pipes).
Optimal periods for planting trees in Colorado are spring (March 15 to June 15) and fall (September 1 to October 15), when outdoor temperatures are not so extreme.
For a video on how to plant a tree, plus tips on selecting, watering and pruning trees, please visit the CSFS website at http://bit.ly/CSFSTreeCare.
For descriptions of trees suitable to plant throughout Colorado, please visit the Colorado Tree Coalition’s website at coloradotrees.org/find. Please visit extension.colostate.edu/docs/pubs/garden/treereclist.pdf for a list of trees recommended for the Front Range.
For more information on the history of Arbor Day, visit arborday.org/celebrate/history.cfm.