If you’re wondering when to plant shrubs in Colorado, timing is everything for success. The state’s unique climate, with its intense sun, drying winds, and dramatic temperature swings, makes choosing the right planting window the most important step.
Get it right, and your shrubs will establish strong roots and thrive for years. Plant at the wrong time, and they’ll struggle with stress, drought, or winter damage. This guide gives you the clear, practical advice you need to plant with confidence.
When to Plant Shrubs in Colorado
The best times to plant shrubs in Colorado are during the “shoulder seasons”—spring and fall. These periods offer the mild temperatures and natural moisture that help roots grow without the strain of summer heat or winter cold.
The Ideal Planting Windows
Spring Planting: Aim for late April through mid-June. Wait until the soil is workable and no longer frozen or soggy. The goal is to get shrubs in the ground after the last hard frost but before the summer heat hits.
- Pros: Gives shrubs a full growing season to establish before winter.
- Cons: Requires more vigilant watering through the summer.
Fall Planting: Target early September through mid-October. You want the soil to still be warm, but the air temperatures to be cooling down.
- Pros: Less heat stress, more natural precipitation, and roots can grow until the ground freezes.
- Cons: A very late, harsh freeze can threaten poorly established plants.
Why Summer and Winter Are Risky
Planting in the Colorado summer (July-August) is generally not advised. The intense sun and low humidity cause extreme transplant shock. New shrubs can’t take up water fast enough to replace what’s lost, leading to scorch or death.
Winter planting is impossible due to frozen ground. Even late fall planting after the ground is cold is risky, as roots won’t grow and the shrub will essentially sit there, vulnerable, until spring.
Exceptions Based on Your Zone
Colorado’s gardening zones range from cold 3a to milder 6a and even higher in microclimates. Your specific location adjusts the calendar.
- Front Range (Zones 5-6): Follow the standard spring/fall windows above.
- High Mountains (Zones 3-4): Opt for spring planting only. Fall comes too early, and winters are too severe for fall-planted shrubs to settle in.
- Western Slopes & Grand Valley (Zones 6-7): You can often extend fall planting later into October, thanks to milder winters.
Special Case: Container vs. Balled-and-Burlapped Shrubs
Most shrubs you buy will be in containers. These offer more flexibility and can be planted anytime the ground isn’t frozen, though spring and fall are still best.
Balled-and-burlapped (B&B) shrubs have a heavier root ball wrapped in fabric. They are best planted in spring or early fall, as the disturbance to their roots is greater.
How to Plant Your Shrubs Correctly
Proper planting technique is just as crucial as timing. Here’s a step-by-step method proven for Colorado conditions.
Step 1: Choose the Right Shrub
Always select shrubs labeled for your zone or colder. Native and drought-tolerant species like Rabbitbrush, Sand Cherry, or Three-leaf Sumac are adapted to thrive here with less fuss.
Step 2: Prepare the Planting Hole
Dig a hole that is 2-3 times wider than the root ball, but no deeper. The shrub should sit so its root flare (where roots meet stem) is slightly above ground level. This prevents settling and rot.
Step 3: Amend the Soil (The Colorado Way)
Our clay soil is tough. Don’t just backfill with it alone. Mix your native soil with a quality compost or planting mix at a 50/50 ratio. This improves drainage and gives roots a better start.
Step 4: Plant and Water Deeply
Place the shrub in the hole, backfill with your soil mix, and tamp down gently. Create a low soil berm around the edge to form a watering basin. Then, water slowly and thoroughly until the entire root zone is soaked.
Step 5: Mulch and Protect
Apply 2-3 inches of wood chip mulch around the base, keeping it a few inches away from the stem. Mulch conserves moisture, regulates soil temperature, and supresses weeds.
Caring for Newly Planted Shrubs
The first two years are critical for establishment. Your care routine makes all the difference.
Watering Schedule is Non-Negotiable
Deep, infrequent watering encourages deep roots. Here’s a general guide:
- Weeks 1-4: Water every 2-3 days.
- Months 2-3: Water deeply once a week.
- First Year: Water every 10-14 days, depending on weather. Always check soil moisture first.
- Year Two: Water every 2-3 weeks, tapering off as the shrub matures.
Water in the morning to reduce evaporation and fungal disease. In winter, remember to water during dry, warm spells when the ground isn’t frozen—this is a common oversight.
Protection from Sun and Wind
New shrubs can sunburn or dry out from wind. Consider using a temporary shade cloth on the south or west side for the first summer. Staking may be necessary for taller shrubs in windy areas, but remove stakes after one year.
When to Fertilize
Avoid fertilizing at planting time. It can burn new roots. Wait until the shrub has been in the ground for at least 6-8 weeks, or better yet, until its second growing season. A light application of a slow-release, balanced fertilizer in spring is usually sufficient.
Pruning After Planting
Resist the urge to prune heavily at planting. Only remove broken, dead, or crossing branches. The leaves are needed to produce energy for root growth. Major shaping can wait a year or two.
Common Mistakes to Avoid
- Planting too deep: This is the number one cause of failure. Keep the root flare visible.
- Overwatering: Soggy soil suffocates roots. Let the soil dry slightly between waterings.
- Ignoring the wind: A temporary windbreak can prevent broken stems and excessive drying.
- Using too much mulch: A “mulch volcano” piled against the stem leads to rot and pest issues.
- Forgetting winter watering: Colorado’s dry winters dessicate plants. Water monthly on warm days.
FAQ: Your Colorado Shrub Questions Answered
What is the absolute best month to plant shrubs in Colorado?
For most of the state, May and September are the ideal months. May offers warming soils and spring moisture. September provides cooling temps and reliable rainfall.
Can I plant shrubs in early spring before the last frost?
You can, but it’s risky. A hard late frost can damage new growth. It’s safer to wait until after your area’s average last frost date. Protect new plantings with frost cloth if a surprise cold snap is forecast.
How late in the fall can you plant shrubs in Colorado?
Aim to finish by mid-October. Roots need about 4-6 weeks of warm soil to establish before the ground freezes solid. If you miss this window, it’s wiser to wait until spring.
What are the best low-water shrubs for Colorado?
Excellent choices include: Apache Plume, Potentilla, Lilac, Rocky Mountain Juniper, and Barberry. These are tough and require minimal water once established, saving you time and resources.
Should I amend the soil when planting shrubs?
Yes, but mix amendments with your native soil. Creating a rich “bathtub” in a clay hole can cause water to pool and roots to circle. Blending compost with your backfill improves structure while encouraging roots to venture out into the native soil.
By following this advice—choosing the right time, planting correctly, and providing attentive follow-up care—you give your Colorado shrubs the strongest possible start. Your reward will be a beautiful, resilient landscape that enhances your garden for many seasons to come.