If you’re wondering when to plant trees in Colorado, timing is everything for their survival. The best time for planting is during the dormant seasons, but Colorado’s unique climate demands a more specific schedule.
Planting at the right moment gives your tree’s roots a chance to establish without the stress of extreme heat or frozen ground. This simple step is the most important thing you can do to ensure your new tree thrives for decades.
When To Plant Trees In Colorado – Best Time For Planting
The short answer is that fall is generally the champion, with spring as a strong runner-up. Let’s break down why these seasons work and how to choose between them.
Why Fall (September to Mid-October) is Ideal
Fall planting leverages the warm soil and cooler air of autumn. The tree can focus its energy on root growth instead of supporting leaves.
- Warm Soil: Soil stays warm long after air temperatures drop, encouraging root development.
- Cooler Air: Reduced heat stress means the tree loses less water through its leaves.
- Natural Moisture: Fall rains (and winter snows) provide consistent moisture for root establishment.
- Head Start: A fall-planted tree is ready to explode with growth the following spring, already settled in.
Spring Planting (April to Early June)
Spring is the second-best option, especially for more tender species. The key is to plant as soon as the ground is workable.
- Workable Soil: Plant after the frost leaves the ground and it’s no longer soggy from melt.
- Before the Heat: Get your tree in the ground well before Colorado’s intense summer sun arrives.
- Monitor Water: Spring-planted trees require diligent watering through their first summer, as they have a smaller root system to cope with heat.
Seasons to Avoid
Summer and winter planting are risky in Colorado’s climate.
- Summer (July-August): High heat and low humidity cause extreme transplant shock. Watering demands are very high and success rates are low.
- Winter (Late Nov-Feb): Frozen ground makes proper planting impossible. Roots cannot grow in frozen soil, leaving the tree vulnerable.
Colorado’s Climate Zones Matter
Your specific location in the state fine-tunes the calendar. Colorado isn’t just one climate.
Front Range & Urban Corridors (Zone 5-6)
This includes Denver, Colorado Springs, and Fort Collins. Fall planting from mid-September to October 20th is perfect. Spring planting from mid-April to May is also good.
High Mountains (Zone 3-4)
For towns above 7,000 feet, the window is shorter. Aim for late May to late June for spring planting. For fall, plant as soon as possible after Labor Day, as early frosts arrive quickly.
Western Slopes & Grand Valley (Zone 6-7)
Areas like Grand Junction have milder winters but hotter, drier summers. Fall planting is excellent here, often into early November. Spring planting should be done very early, in March or April, to beat the heat.
Step-by-Step Guide to Planting Your Tree
Once you’ve chosen your time, doing the job right is crucial. Follow these steps for the best results.
- Call Before You Dig: Always dial 811 at least a few business days before planting. This ensures you won’t hit underground utilities.
- Choose the Right Tree: Select a species native or well-adapted to your specific Colorado zone. A local nursery can give the best advice.
- Dig a Wide, Shallow Hole: The hole should be 2-3 times wider than the root ball but only as deep as the root ball is tall. Do not dig deeper!
- Handle the Root Ball: Gently remove any container or burlap. Inspect the roots and gently tease apart any that are circling the root ball.
- Place the Tree: Set the tree in the hole so the root flare (where the trunk widens at the base) is slightly above the surrounding soil level.
- Backfill with Native Soil: Use the soil you dug out to backfill. Do not amend it with compost or potting mix, as this can discourage roots from venturing into native soil.
- Water Deeply: As you backfill, water to settle the soil and remove air pockets. Create a small soil berm around the edge to form a watering basin.
- Mulch Generously: Apply 3-4 inches of wood chip mulch in a wide circle around the tree. Keep the mulch a few inches away from the trunk itself to prevent rot.
- Stake Only if Necessary: Most young trees do not need staking. Only stake if the site is very windy, and use loose, flexible ties.
Aftercare: The First Two Critical Years
Your job isn’t over after planting. Consistent aftercare, especially watering, is what truly ensures success.
Watering Schedule
Deep, infrequent watering is better than frequent sprinkles. It encourages deep roots.
- Weeks 1-4: Water every 2-3 days.
- Months 2-3: Water once a week.
- Until Dormancy (Year 1): Water every 10-14 days, depending on rainfall and heat.
- Year 2: Water deeply every 2-3 weeks during dry periods. The goal is to wean the tree to rely on natural precipitation.
Always check soil moisture a few inches down before watering. Overwatering can be as harmful as underwatering in our climate.
Mulch Refreshing and Inspection
Refresh the mulch layer each spring, maintaining that 3-4 inch depth. Keep it away from the trunk. Periodically check for pests, damage, or disease, but avoid the temptation to over-prune. Only remove dead, damaged, or crossing branches in the first few years.
Common Mistakes to Avoid
Even with good timing, these errors can set your tree back.
- Planting Too Deep: This is the #1 cause of tree failure. The root flare must be visible.
- Over-Amending the Soil: As mentioned, backfill with native soil to encourage strong, spreading roots.
- Volcano Mulching: Piling mulch against the trunk invites disease, insects, and rodents.
- Incorrect Watering: Letting the root ball dry out completely or keeping it constantly soggy.
- Choosing the Wrong Species: A tree not suited for your zone or Colorado’s dry climate will struggle no matter when you plant it.
Best Tree Choices for Colorado
Opting for resilient, drought-tolerant species sets you up for success. Here are some reliable choices:
- Shade Trees: Hackberry, Bur Oak, Kentucky Coffeetree, Western Catalpa.
- Ornamental & Smaller Trees: Serviceberry, Hawthorn, Canada Red Chokecherry, Pinyon Pine.
- Conifers: Colorado Blue Spruce (watch for disease in urban areas), Ponderosa Pine, Southwestern White Pine.
Always consult with a local arborist or nursery for the best selection for your exact yard conditions, like sun exposure and soil type.
FAQ: Planting Trees in Colorado
Can I plant a tree in Colorado in the summer if I water it a lot?
It’s not recommended. Even with frequent watering, the heat stress on the tree’s foliage and the high rate of evaporation make establishment very difficult. Survival rates drop significantly.
Is May too late to plant trees in Colorado?
May is usually fine for spring planting, especially in cooler areas. On the Front Range, late May is pushing it before summer heat. Aim for April or early May for a safer margin.
What is the best month to plant trees in Denver?
For fall planting, aim for October. For spring planting, April is ideal. These months typically offer the best balance of soil temperature and moisture.
How do I protect a newly planted tree from late spring frost?
If a hard frost is forecast after leaves have emerged, you can loosely drape a frost cloth or old sheet over the tree for the night. Remove it during the day. Avoid using plastic directly on the foliage.
Can I plant fruit trees at the same time?
Yes, the same seasonal guidelines apply. Fruit trees are often more susceptible to frost damage on blossoms, so choosing a protected site is extra important. Their watering needs may also be higher during fruit production.
By choosing the right time—preferably the fall dormancy period—and following proper planting techniques, you give your tree the strongest possible start. Paying attention to Colorado’s regional variations and committing to thoughtful aftercare will help your investment grow into a healthy, beautiful part of the landscape for generations to come. Remember, the few extra minutes you spend planning and planting correctly will pay off for a lifetime.