Temperatures are dropping below freezing in the Denver metro. Time to act fast to protect your plants.
🪴 Bring pots inside
Any potted plants on patios, decks, or balconies — move them indoors or into a garage
🧥 Cover in-ground plants
Use frost cloth, old bedsheets, or newspaper to cover tender perennials and new transplants
🌊 Water before it freezes
Moist soil holds heat better than dry soil — water Thursday evening before temps drop
🚿 Shut off irrigation
Turn off any automatic sprinklers or drip systems to prevent frozen lines
🌱 Colorado Gardening Guide
What to Plant & When in Colorado
A homeowner's guide to Colorado's unique growing season — frost dates, planting calendars, and the surprising ways a beautiful yard can boost your home's value.
📍 Denver Metro Focus🌡️ Zone 5b / 6a📅 Updated for 2026
Colorado's climate is one of the most beautiful — and most unpredictable — in the country. We get 300+ days of sunshine, but we also get surprise June snowstorms. Knowing exactly when to plant isn't just about a prettier yard. It's about protecting your investment, avoiding wasted effort, and making the most of a short but rewarding growing season.
Know Your Frost Dates First
Everything starts here. Planting too early is the #1 mistake Colorado gardeners make.
Denver Metro — Average Frost Dates
Last Spring Frost
May 7–15
Safe to plant warm crops after this
First Fall Frost
Oct 7–15
Start wrapping up warm-season plants
⚠️ Colorado can see surprise snow in late May and even early June — always watch the 10-day forecast before putting warm-season plants in the ground.
Month-by-Month Planting Calendar
Timed for the Denver metro (Zone 5b/6a). Adjust by 1–2 weeks earlier for lower elevations, 1–2 weeks later above 6,500 ft.
Start indoors
Plant outdoors
Caution / frost risk
Trees & shrubs
❄️January – February
Start onions, leeks & celery indoorsStart perennial flowers indoors (lavender, echinacea)Plan your beds — order seeds now
🌤️March
Start tomatoes, peppers & eggplant indoors (6–8 weeks before last frost)Start broccoli, cabbage & cauliflower indoorsDirect sow spinach, lettuce & kale outdoors — they can handle light frostGood time to plant bare-root trees while dormant
🌸April
Transplant cold-hardy starts (broccoli, cabbage) outdoors — watch frostDirect sow peas, carrots, radishes & beetsStart cucumbers & squash indoorsPlant deciduous trees & shrubs — spring rains help establishmentDo NOT put tomatoes, peppers or basil out yet — frost will kill them
🌷May
Early May: harden off warm-season starts — bring outside during dayAfter May 15: transplant tomatoes, peppers, basil outdoorsDirect sow beans, corn, cucumbers & squash after frost datePlant annual flowers: marigolds, zinnias, petunias, cosmosPlant ornamental trees — crabapple, serviceberry, aspen
☀️June
Safe to plant everything — full summer garden goes inSuccession plant lettuce & radishes for fall harvestPlant sunflowers directly — they love Colorado sunMulch beds to retain moisture through hot July & August
🍅July – August
Harvest season begins — tomatoes, beans, squash, cucumbersMid-July: start fall crops indoors (broccoli, cauliflower)Water deeply but less frequently — train roots to go deepLate summer is great for planting ornamental grasses & native perennials
🍂September – October
Direct sow spinach & kale for fall harvest before first frostPlant spring bulbs: tulips, daffodils, crocus (plant before ground freezes)Excellent time to plant trees & shrubs — cool soil, fall rains, roots establish before winterBring in tender plants after first frost warning
🌨️November – December
Mulch perennials & rose beds before hard freezePlant garlic for next year — before ground freezesStart planning & ordering seeds for next season
Your Yard Is an Investment
A well-planted yard isn't just beautiful — it directly affects what your home is worth.
🌳
10–15%
Potential increase in home value from mature trees, per the USDA Forest Service
🏡
7%
Higher sale prices from strong curb appeal, according to a National Association of Realtors study
💧
$500+
Annual energy savings from strategically placed shade trees on south and west exposures
Best Plants for Colorado Homes
Hardy, beautiful, and great for your home's curb appeal. These all thrive in Denver metro conditions.
🌳 Tree
Quaking Aspen
Colorado's signature tree. Stunning gold fall color, fast growing, and gives buyers that mountain-home feeling. Groups of 3 look best.
Incredible spring blooms in pink or white, followed by small colorful fruits. Disease-resistant varieties do great in Colorado's dry climate.
✓ One of the most-photographed spring trees — huge visual impact
🌺 Perennial
Black-Eyed Susan
Drought-tolerant native that blooms bright yellow from June through frost. Returns every year with minimal care — perfect for Colorado.
✓ Low-maintenance native — appeals to buyers who want easy yards
🌺 Perennial
Lavender
Thrives in Colorado's dry, sunny climate. Purple blooms all summer, drought-resistant once established, and smells incredible.
✓ High perceived value — buyers associate lavender with premium homes
🌿 Shrub
Serviceberry (Amelanchier)
Four-season beauty: white spring blooms, edible summer berries, brilliant fall color. Native to Colorado and incredibly tough.
✓ Native, edible, and beautiful — a rare combination
🌿 Shrub
Blue Spruce
Colorado's state tree. The silvery-blue color is striking year-round and instantly signals "this is a well-maintained Colorado home."
✓ Year-round color and structural presence that photographs beautifully
🌿 Quick Tips for Colorado Gardeners
💧Water deeply, not often. Colorado's clay and sandy soils both benefit from slow, deep watering 1–2x per week rather than daily shallow watering. This trains roots to grow deep and survive dry spells.
🌬️Harden off before transplanting. Seedlings started indoors need 7–10 days of gradual outdoor exposure before going in the ground. Start with a few hours of shade and work up to full sun.
🌡️Watch the 10-day forecast in May. Colorado's last frost date averages May 7–15, but we've seen hard freezes in late May and even early June. A $2 frost cloth can save a whole season of work.
🍂Fall is underrated for planting trees. September–October is actually the best time to plant trees and shrubs in Colorado. Cooler temperatures mean less transplant stress, and fall rains help roots establish before winter.
🌱Go native when you can. Plants native to Colorado — blue grama grass, penstemons, serviceberry, rabbitbrush — evolved here. They use less water, survive temperature swings, and support local pollinators.
