When to Plant Mustard Greens in Washington County, CO
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.
Washington County, Colorado is in USDA Zone 5a. The average last spring frost is May 10 and the first fall frost is October 5, giving you a growing season of approximately 148 days.
At an elevation of 6,091 feet, Washington County receives approximately 13 inches of rainfall annually with predominantly loam soil. Summer highs average 85°F, providing good warmth for Mustard Greens during the growing season. With low rainfall, drip irrigation is essential for growing Mustard Greens successfully. Mulch heavily to conserve soil moisture.
Washington County Soil Profile
Soil Type
Loam
Soil pH
6.8-8.3
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.
Plant Water Budget
Water stress score is 10/10 — consider drought-tolerant varieties and mulching
Mustard Greens Planting Timeline — Washington County, CO
Mustard Greens Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | April 5 | Apr 5 – Apr 19 |
| Transplant Outdoors | May 10 | May 10 – May 24 |
| Direct Sow | April 26 | Apr 26 – May 17 |
| Fall Sowing | July 27 | Jul 27 – Aug 10 |
| Harvest | June 14 | Jun 14 – Aug 16 |
Plant 0.5" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Start Indoors Direct Sow |
| May | Transplant Outdoors Direct Sow |
| June | Harvest |
| July | Fall Sowing Harvest |
| August | Fall Sowing Harvest |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
Sun
Partial Shade (3-6 hours)
Water
Moderate — regular watering
Days to Maturity
30–50 days
Soil pH
6 – 7
USDA Zone
Zone 5a
Growing Season
148 days
Growing Tips for Washington County
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
Level Up Your Garden
Mustard Greens in Other Locations
Frequently Asked Questions
When should I plant Mustard Greens in Washington County, CO?
Washington County is in Zone 5a with an average last frost of May 10. Plan your Mustard Greens planting based on this frost date — see the calendar above for exact timing.
What planting zone is Washington County, CO?
Washington County, Colorado is in USDA Hardiness Zone 5a. The average last spring frost is May 10 and first fall frost is October 5.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Washington County gardeners in Zone 5a organize planting dates, track what's growing, and never miss a planting window.
Get Your Free Garden Planner →Free download. Plan your entire garden season in minutes.