When to Plant Mustard Greens in Grand County, CO
May to-do list for Grand County, Colorado
Welcome to May in Zone 5a. These are the moves that will have the biggest impact on your growing season.
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Move mustard greens from tray to bed
Your last frost (May 28) has passed. These warm-season crops can handle outdoor soil now.
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Scatter mustard greens into prepared beds
Rake a smooth bed, make a shallow furrow, drop seeds at the spacing on the packet, water gently, walk away.
Mustard greens are fast-growing brassicas with a spicy, peppery kick. They come in green, red, and purple varieties and are excellent cooked or in salads.
Grand County, Colorado is in USDA Zone 5a. The average last spring frost is May 28 and the first fall frost is September 19, giving you a growing season of approximately 114 days.
At an elevation of 5,397 feet, Grand County receives approximately 22.2 inches of rainfall annually with predominantly loam soil. Summer highs average 82°F, so choose short-season varieties of Mustard Greens to ensure they mature before fall.
Grand County Soil Profile
Soil Type
Loam
Soil pH
6.7-8.3
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 Grand County
How your county's soil matches Mustard Greens's growing requirements.
Soil pH
Your soil pH (6.7–8.3) is more alkaline than Mustard Greens prefers (6.0–7.0). Add sulfur or peat moss to lower pH.
Soil Texture
The loam soil in Grand County is excellent for Mustard Greens — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Drainage is adequate for Mustard Greens.
Organic Matter
Organic matter is moderate (2.2%). Annual compost additions will help Mustard Greens.
How to Plant Mustard Greens
Fall planting: Sow 10 weeks before your first frost date for a fall harvest.
Succession Planting Mustard Greens
Sow every 3.4 weeks. Last sowing by Jul 31 to harvest before frost.
For a dedicated fall crop, sow by Jul 11.
Plant Water Budget
Water stress score is 8/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Mustard Greens
Mustard Greens needs approximately 0.7 inches of water per week (3" per month). Here's how your county's rainfall compares month by month.
| Month | Mustard Greens Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.7" | 0" | ❄️ Dormant |
| Feb | — | 1.2" | 0" | ❄️ Dormant |
| Mar | — | 1.9" | 0" | ❄️ Dormant |
| Apr | — | 2.1" | 0" | ❄️ Dormant |
| May | 3" | 3" | 0" | ✅ Rainfall sufficient |
| Jun | 3" | 1.5" | 1.5" | 🚿 Regular watering |
| Jul | 3" | 2" | 1" | 💧 Light watering |
| Aug | 3" | 2.3" | 0.7" | 💧 Light watering |
| Sep | 3" | 1.6" | 1.4" | 💧 Light watering |
| Oct | — | 2.2" | 0" | ❄️ Dormant |
| Nov | — | 1.5" | 0" | ❄️ Dormant |
| Dec | — | 1.2" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Sep in Grand County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Mustard Greens 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.
Mustard Greens Planting Timeline — Grand County, CO
Mustard Greens Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | April 23 | Apr 23 – May 7 |
| Transplant Outdoors | May 28 | May 28 – Jun 11 |
| Direct Sow | May 14 | May 14 – Jun 4 |
| Harvest | July 2 | Jul 2 – Sep 3 |
| Fall Sowing | July 11 | Jul 11 – Jul 25 |
Plant 0.5" deep · 6" apart · Rows 12" 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 |
| July | Fall Sowing Harvest |
| August | Harvest |
| September | Harvest |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Partial Shade (3-6 hours)
💧 Water
0.7"/week · Only during dry spells
📅 Days to Maturity
30–50 days
🧪 Soil pH
Needs 6–7 · Your soil: too_alkaline
🗺️ USDA Zone
Zone 5a
📆 Growing Season
114 days in Grand County
Growing Tips for Mustard Greens in Grand County
Direct sow Mustard Greens outdoors after May 28 in Grand County when soil has warmed and frost danger has passed.
Common pests for Mustard Greens in this region include cabbage worm and flea beetles. Use row covers early in the season and inspect plants weekly.
General growing tips
Direct sow in early spring or fall. Harvest young leaves for milder flavor. Plants bolt quickly in heat so grow as a cool-season crop or provide shade.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Mustard Greens in Other Locations
Frequently Asked Questions
When should I plant Mustard Greens in Grand County, CO?
Grand County is in Zone 5a with an average last frost of May 28. Plan your Mustard Greens planting based on this frost date — see the calendar above for exact timing.
What planting zone is Grand County, CO?
Grand County, Colorado is in USDA Hardiness Zone 5a. The average last spring frost is May 28 and first fall frost is September 19.
Your Grand County Garden Planner — Free
A 24-page printable planner built for Grand County (Zone 5a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.