When to Plant Brussels Sprouts in Alamosa County, CO
Brussels sprouts are a cold-hardy brassica that produces miniature cabbage-like heads along a tall stalk. Flavor improves after a light frost.
Alamosa County, Colorado is in USDA Zone 4b. The average last spring frost is May 31 and the first fall frost is September 19, giving you a growing season of approximately 111 days.
At an elevation of 8,366 feet, Alamosa County receives approximately 18.3 inches of rainfall annually with predominantly loam soil. Summer highs average 81°F, so choose short-season varieties of Brussels Sprouts to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Brussels Sprouts successfully. Mulch heavily to conserve soil moisture.
Alamosa County Soil Profile
Soil Type
Loam
Soil pH
6.4-8
Drainage
Well Drained
Plant 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 Alamosa County
How your county's soil matches Brussels Sprouts's growing requirements.
Soil pH
Your soil pH (6.4–8.0) overlaps with Brussels Sprouts's range (6.0–7.5), though not a perfect match.
Soil Texture
The loam soil in Alamosa County is excellent for Brussels Sprouts — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (2.3%). Annual compost additions will help Brussels Sprouts.
How to Plant Brussels Sprouts
Fall planting: Sow 12 weeks before your first frost date for a fall harvest.
Plant Water Budget
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Brussels Sprouts
Brussels Sprouts needs approximately 0.9 inches of water per week (3.9" per month). Here's how your county's rainfall compares month by month.
| Month | Brussels Sprouts Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.3" | 0" | ❄️ Dormant |
| Feb | — | 1.1" | 0" | ❄️ Dormant |
| Mar | — | 1.5" | 0" | ❄️ Dormant |
| Apr | — | 1.9" | 0" | ❄️ Dormant |
| May | 3.9" | 2" | 1.9" | 💧 Light watering |
| Jun | 3.9" | 1.5" | 2.4" | 🚿 Regular watering |
| Jul | 3.9" | 1.5" | 2.4" | 🚿 Regular watering |
| Aug | 3.9" | 1.9" | 2" | 🚿 Regular watering |
| Sep | 3.9" | 1.4" | 2.5" | 🚿 Regular watering |
| Oct | — | 1.6" | 0" | ❄️ Dormant |
| Nov | — | 1.6" | 0" | ❄️ Dormant |
| Dec | — | 1" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Sep in Alamosa County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Brussels Sprouts 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.
Brussels Sprouts Planting Timeline — Alamosa County, CO
Brussels Sprouts Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | April 19 | Apr 19 – May 3 |
| Transplant Outdoors | May 31 | May 31 – Jun 14 |
| Direct Sow | May 24 | May 24 – Jun 14 |
| Harvest | August 30 | Aug 30 – Oct 25 |
| Fall Sowing | June 27 | Jun 27 – Jul 11 |
Plant 1" deep · 15" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Start Indoors |
| May | Start Indoors Transplant Outdoors Direct Sow |
| June | Transplant Outdoors Direct Sow Fall Sowing |
| July | Fall Sowing |
| August | Harvest |
| September | Harvest |
| October | Harvest |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.9"/week · Only during dry spells
📅 Days to Maturity
90–130 days
🧪 Soil pH
Needs 6–7.5 · Your soil: acceptable
🗺️ USDA Zone
Zone 4b
📆 Growing Season
111 days in Alamosa County
Growing Tips for Brussels Sprouts in Alamosa County
Direct sow Brussels Sprouts outdoors after May 31 in Alamosa County when soil has warmed and frost danger has passed.
Your 111.0-day growing season in Alamosa County is tight for Brussels Sprouts (90.0-130.0 days to maturity). Start indoors and choose early-maturing varieties.
Common pests for Brussels Sprouts in this region include cabbage worm and flea beetles. Use row covers early in the season and inspect plants weekly.
Alamosa County receives only 18" of rain annually. Brussels Sprouts needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.
General growing tips
Start seeds indoors 12-14 weeks before first fall frost. Stake tall plants to prevent toppling. Remove lower leaves as sprouts develop to improve air circulation.
Companion Planting
Good Companions
Avoid Planting Near
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Brussels Sprouts in Other Locations
Frequently Asked Questions
When should I plant Brussels Sprouts in Alamosa County, CO?
Alamosa County is in Zone 4b with an average last frost of May 31. Plan your Brussels Sprouts planting based on this frost date — see the calendar above for exact timing.
What planting zone is Alamosa County, CO?
Alamosa County, Colorado is in USDA Hardiness Zone 4b. The average last spring frost is May 31 and first fall frost is September 19.
Plan Your Garden with Confidence
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