When to plant Daffodils in Boulder County County,
Boulder County County gardeners should plant Daffodils between mid-spring and late spring in spring. With Boulder County County's Zone 6a climate (last frost May 14), Daffodils needs 40 days to mature — plant by August 17 for a full harvest. A second sowing from August 15 to August 29 extends the harvest into fall.
When to Plant Daffodils in Boulder County, CO
June to-do list 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.
Daffodils (Narcissus spp.) are among the most dependable and longest-lived of all spring bulbs. Their cheerful yellow and white blooms emerge in early spring, often while frost is still possible, bringing color weeks before most other flowers. Unlike tulips, established clumps naturalize readily — spreading and returning reliably year after year without replanting. Deer and rodents avoid them due to toxic alkaloids in the bulb and sap, making them a low-maintenance choice for naturalized areas, woodland edges, and mixed borders.
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 Daffodils during the growing season.
Boulder County Soil Profile
Soil Type
Loam
Soil pH
6.7-8
Drainage
Well Drained
Daffodils 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 Daffodils's growing requirements.
Soil pH
Your soil pH (6.7–8.0) is more alkaline than Daffodils prefers (6.0–7.0). Add sulfur or peat moss to lower pH.
Soil Texture
The loam soil in Boulder County is excellent for Daffodils — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Drainage is adequate for Daffodils.
Organic Matter
Organic matter is moderate (2.3%). Annual compost additions will help Daffodils.
How to Plant Daffodils
Fall planting: Sow 6 weeks before your first frost date for a fall harvest.
Succession Planting Daffodils
Sow every 2.3 weeks. Last sowing by Aug 17 to harvest before frost.
For a dedicated fall crop, sow by Aug 15.
Daffodils Water Budget
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Daffodils
Daffodils needs approximately 0.5 inches of water per week (2.2" per month). Here's how your county's rainfall compares month by month.
| Month | Daffodils 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 | 2.2" | 3" | 0" | ✅ Rainfall sufficient |
| Jun | 2.2" | 1.6" | 0.6" | 💧 Light watering |
| Jul | 2.2" | 2" | 0.2" | 💧 Light watering |
| Aug | 2.2" | 2.1" | 0.1" | 💧 Light watering |
| Sep | 2.2" | 2.1" | 0.1" | 💧 Light 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.
Daffodils 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.
Daffodils Planting Timeline — Boulder County, CO
Daffodils Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Bloom | July 11 | Jul 11 – Aug 1 |
| Fall Sowing | August 15 | Aug 15 – Aug 29 |
Plant 7" deep · 7" apart · Rows 8" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | — |
| May | — |
| June | — |
| July | Bloom |
| August | Fall Sowing Bloom |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.5"/week · Natural rainfall sufficient
📅 Days to Maturity
20–40 days
🧪 Soil pH
Needs 6–7 · Your soil: too_alkaline
🗺️ USDA Zone
Zone 6a
📆 Growing Season
135 days in Boulder County
Growing Tips for Daffodils in Boulder County
Direct sow Daffodils outdoors after May 14 in Boulder County when soil has warmed and frost danger has passed.
Your generous 135.0-day season in Boulder County allows multiple plantings of Daffodils. Sow every 10.0 days for continuous harvest.
Common pests for Daffodils in this region include onion maggots and thrips. Use row covers early in the season and inspect plants weekly.
Boulder County receives only 22" of rain annually. Daffodils needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.
General growing tips
Plant bulbs pointed-end up in fall, 6–8 inches deep and 6–8 inches apart in well-drained soil. Allow 12–16 weeks of cold dormancy for proper vernalization. Do not cut back foliage until it turns yellow (6–8 weeks after bloom) — the dying leaves photosynthesize energy into the bulb for next year. Lift and divide overcrowded clumps every 4–5 years in summer after foliage dies back. In zones 7b–9b, select heat-tolerant cultivars (Jonquilla, Tazetta, and Cyclamineus divisions) that perform better with less chill than large-cupped types. Zones 10+: insufficient winter cold; pre-chilling is required but results inconsistent — not recommended for outdoor culture.
Companion Planting
Good Companions
Check more plant combinations with our Companion Planting Checker →
Daffodils in Other Locations
Frequently Asked Questions
When should I plant Daffodils in Boulder County, CO?
Boulder County is in Zone 6a with an average last frost of May 14. Plan your Daffodils 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 Daffodils in Boulder County County, ?
In Boulder County County, , plant Daffodils 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 County, for Daffodils?
Boulder County County sits in USDA Zone 6a. Daffodils grows reliably in zones 3a through 9b, so it's a good fit here.
Can Daffodils grow in Boulder County County's climate?
Yes — Daffodils grows well in Boulder County County's temperate climate. Boulder County 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.