When to plant Pansy in Boulder County, CO
Boulder County sits in USDA Zone 6a. Plant Pansy between May 14 (after last frost on May 14) and May 28. A second sowing from August 1 to August 15 extends the harvest into fall.
When to Plant Pansy in Boulder County, CO
Your June planting checklist for Boulder County, Colorado
If you only do a handful of things in the garden this June, make it these. They're sequenced around your zone's frost timing.
Coming up in July — start thinking about
- Starting indoors: pansy
- First harvests: pansy
Pansies (Viola × wittrockiana) are beloved cool-season annuals offering some of the widest color range in the annual garden. Their cheerful "faces" appear in early spring — or even late winter in mild climates — and hold up remarkably well through frosts. Heat causes them to go leggy and stop blooming; replace with warm-season annuals once daytime temps exceed 70°F.
Boulder County, Colorado is in USDA Zone 6a. The average last spring frost is May 14 and the first fall frost is September 26, giving you a growing season of approximately 135 days.
At an elevation of 7,657 feet, Boulder County receives approximately 22.2 inches of rainfall annually with predominantly loam soil. Summer highs average 86°F, providing good warmth for Pansy during the growing season.
Boulder County Soil Profile
Soil Type
Loam
Soil pH
6.7-8
Drainage
Well Drained
Pansy Planting Risk Windows
Percentages indicate frost risk at transplant. The 70% safe window means there is a 30% chance of frost after transplant — suitable for cold-hardy crops or gardeners with frost protection. The 90% safe window is best for tender plants.
Soil Compatibility in Boulder County
How your county's soil matches Pansy's growing requirements.
Soil pH
Your soil pH (6.7–8.0) is more alkaline than Pansy prefers (5.4–6.2). Add sulfur or peat moss to lower pH.
Soil Texture
The loam soil in Boulder County is excellent for Pansy — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Drainage is adequate for Pansy.
Organic Matter
Organic matter is moderate (2.3%). Annual compost additions will help Pansy.
How to Plant Pansy
Fall planting: Sow 8 weeks before your first frost date for a fall harvest.
Succession Planting Pansy
Sow every 8 weeks. Last sowing by Jun 28 to harvest before frost.
For a dedicated fall crop, sow by Aug 01.
Pansy Water Budget
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Pansy
Pansy needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Pansy Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.7" | 0" | ❄️ Dormant |
| Feb | — | 1.3" | 0" | ❄️ Dormant |
| Mar | — | 1.8" | 0" | ❄️ Dormant |
| Apr | — | 2.2" | 0" | ❄️ Dormant |
| May | 4.3" | 3" | 1.3" | 💧 Light watering |
| Jun | 4.3" | 1.6" | 2.7" | 🚿 Regular watering |
| Jul | 4.3" | 2" | 2.3" | 🚿 Regular watering |
| Aug | 4.3" | 2.1" | 2.2" | 🚿 Regular watering |
| Sep | 4.3" | 2.1" | 2.2" | 🚿 Regular watering |
| Oct | — | 1.9" | 0" | ❄️ Dormant |
| Nov | — | 1.4" | 0" | ❄️ Dormant |
| Dec | — | 1.2" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Sep in Boulder County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Pansy Heat Requirements (GDD)
What are Growing Degree Days (GDD)?
Growing Degree Days measure the total warmth your plants receive during the growing season. Think of it as a "heat bank" — every day above 50°F deposits warmth that helps your plants grow.
Each plant needs a certain amount of accumulated heat to mature. If your county provides more GDD than the plant needs, it's a great fit. If it's close, you may want to choose faster-maturing varieties or start seeds indoors to get a head start.
Pansy Planting Timeline — Boulder County, CO
Pansy Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 5 | Mar 5 – Mar 19 |
| Transplant Outdoors | May 14 | May 14 – May 28 |
| Bloom | July 9 | Jul 9 – Sep 10 |
| Fall Sowing | August 1 | Aug 1 – Aug 15 |
Plant 0.3" deep · 7" apart · Rows 10" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | — |
| May | Transplant Outdoors |
| June | — |
| July | Bloom |
| August | Fall Sowing Bloom |
| September | Bloom |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1"/week · 2-3 times/week
📅 Days to Maturity
70–90 days
🧪 Soil pH
Needs 5.4–6.2 · Your soil: too_alkaline
🗺️ USDA Zone
Zone 6a
📆 Growing Season
135 days in Boulder County
Growing Tips for Pansy in Boulder County
Direct sow Pansy outdoors after May 14 in Boulder County when soil has warmed and frost danger has passed.
Boulder County receives only 22" of rain annually. Pansy needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.
General growing tips
Start indoors 10-12 weeks before last frost for spring transplants. In zones 6+, fall planting (8-10 weeks before first frost) gives overwintering plants that bloom earliest in spring. Plant in full sun in cool weather; afternoon shade helps extend bloom in zones 7-8. Deadhead to prevent premature seed set. Shear back by one-third when plants go leggy to extend the season.
Companion Planting
Good Companions
Check more plant combinations with our Companion Planting Checker →
Pansy in Other Locations
Frequently Asked Questions
When should I plant Pansy in Boulder County, CO?
Boulder County is in Zone 6a with an average last frost of May 14. Plan your Pansy planting based on this frost date — see the calendar above for exact timing.
What planting zone is Boulder County, CO?
Boulder County, Colorado is in USDA Hardiness Zone 6a. The average last spring frost is May 14 and first fall frost is September 26.
When should I plant Pansy in Boulder County, CO?
In Boulder County, CO, plant Pansy after the last frost (around May 14) and before the first frost (around September 26). Best results when soil holds above 50°F.
What growing zone is Boulder County, CO for Pansy?
Boulder County sits in USDA Zone 6a. Pansy grows reliably in zones 3a through 10b, so it's a good fit here.
Can Pansy grow in Boulder County's climate?
Yes — Pansy grows well in Boulder County's temperate climate. Boulder County averages a 135-day frost-free season, with last frost around May 14 and first frost around September 26.
Your Boulder County Garden Planner — Free
A 22-page printable planner built for Boulder County (Zone 6a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.