When to Plant Mizuna in San Juan County, UT
Mizuna is a mild-flavored Japanese mustard green with feathery, deeply serrated leaves. It is fast-growing and makes an excellent addition to salads and stir-fries.
San Juan County, Utah is in USDA Zone 5b. The average last spring frost is May 2 and the first fall frost is October 11, giving you a growing season of approximately 162 days.
At an elevation of 5,225 feet, San Juan County receives approximately 13.7 inches of rainfall annually with predominantly loam soil. Summer highs average 84°F, so choose short-season varieties of Mizuna to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Mizuna successfully. Mulch heavily to conserve soil moisture.
San Juan County Soil Profile
Soil Type
Loam
Soil pH
6.5-7.8
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 San Juan County
How your county's soil matches Mizuna's growing requirements.
Soil pH
Your soil pH (6.5–7.8) overlaps with Mizuna's range (6.0–7.5), though not a perfect match.
Soil Texture
The loam soil in San Juan County is excellent for Mizuna — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (2.5%). Annual compost additions will help Mizuna.
How to Plant Mizuna
Fall planting: Sow 10 weeks before your first frost date for a fall harvest.
Succession Planting Mizuna
Sow every 3.4 weeks. Last sowing by Aug 27 to harvest before frost.
For a dedicated fall crop, sow by Aug 02.
Plant Water Budget
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Mizuna
Mizuna needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Mizuna Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1" | 0" | ❄️ Dormant |
| Feb | — | 0.9" | 0" | ❄️ Dormant |
| Mar | — | 1.1" | 0" | ❄️ Dormant |
| Apr | — | 1.3" | 0" | ❄️ Dormant |
| May | 4.3" | 1.6" | 2.7" | 🚿 Regular watering |
| Jun | 4.3" | 1" | 3.3" | 🚿 Regular watering |
| Jul | 4.3" | 1" | 3.3" | 🚿 Regular watering |
| Aug | 4.3" | 1.6" | 2.7" | 🚿 Regular watering |
| Sep | 4.3" | 1.2" | 3.1" | 🚿 Regular watering |
| Oct | 4.3" | 1.2" | 3.1" | 🚿 Regular watering |
| Nov | — | 0.9" | 0" | ❄️ Dormant |
| Dec | — | 0.9" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Oct in San Juan County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Mizuna 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.
Mizuna Planting Timeline — San Juan County, UT
Mizuna Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 28 | Mar 28 – Apr 11 |
| Transplant Outdoors | May 2 | May 2 – May 16 |
| Direct Sow | April 18 | Apr 18 – May 9 |
| Harvest | June 6 | Jun 6 – Jul 4 |
| Fall Sowing | August 2 | Aug 2 – Aug 16 |
Plant 0.5" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Start Indoors Direct Sow |
| May | Transplant Outdoors Direct Sow |
| June | Harvest |
| July | Harvest |
| August | Fall Sowing |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Partial Shade (3-6 hours)
💧 Water
1"/week · 2-3 times/week
📅 Days to Maturity
30–45 days
🧪 Soil pH
Needs 6–7.5 · Your soil: acceptable
🗺️ USDA Zone
Zone 5b
📆 Growing Season
162 days in San Juan County
Growing Tips for Mizuna in San Juan County
Direct sow Mizuna outdoors after May 02 in San Juan County when soil has warmed and frost danger has passed.
Your generous 162.0-day season in San Juan County allows multiple plantings of Mizuna. Sow every 15.0 days for continuous harvest.
Common pests for Mizuna in this region include cabbage worm and flea beetles. Use row covers early in the season and inspect plants weekly.
San Juan County receives only 14" of rain annually. Mizuna needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.
General growing tips
Direct sow in spring or fall. Harvest outer leaves as needed for a cut-and-come-again approach. Mizuna is one of the most cold-tolerant Asian greens.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Mizuna in Other Locations
Frequently Asked Questions
When should I plant Mizuna in San Juan County, UT?
San Juan County is in Zone 5b with an average last frost of May 2. Plan your Mizuna planting based on this frost date — see the calendar above for exact timing.
What planting zone is San Juan County, UT?
San Juan County, Utah is in USDA Hardiness Zone 5b. The average last spring frost is May 2 and first fall frost is October 11.
Plan Your Garden with Confidence
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