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When to Plant Kohlrabi in San Juan County, NM

San Juan County, New Mexico Zone 7a May

May in the garden — San Juan County, New Mexico

We've pulled the most time-sensitive tasks for San Juan County, New Mexico this May and put them front and centre. Tackle them in order.

Avg. last frost May 12
Avg. first frost October 6
Soil temp (4") 32°F
Watering Critical
Pest pressure Low
Daylight 13.9 hrs
  1. Set out kohlrabi seedlings

    Pick a cloudy afternoon or evening to plant. Less transplant shock, and your seedlings will barely blink.

Coming up in June — start thinking about
  • Starting indoors: kohlrabi
  • First harvests: kohlrabi

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Kohlrabi is an unusual brassica that forms a swollen stem above ground with a mild, sweet turnip-like flavor. Both the bulb and tender leaves are edible.

San Juan County, New Mexico is in USDA Zone 7a. The average last spring frost is May 12 and the first fall frost is October 6, giving you a growing season of approximately 147 days.

At an elevation of 8,301 feet, San Juan County receives approximately 14.3 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 87°F, providing good warmth for Kohlrabi during the growing season. Sandy soil warms quickly in spring — great for early planting — but Kohlrabi will need more frequent watering and organic matter to retain nutrients. With low rainfall, drip irrigation is essential for growing Kohlrabi successfully. Mulch heavily to conserve soil moisture.

San Juan County, NM (Zone 7a) Short season
147 days
Last Spring Frost May 12
147 growing days
First Fall Frost October 6

San Juan County Soil Profile

Soil Type

Sandy Loam

Soil pH

7.3-8.5

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (60 days to spare)
Start indoors: Mar 31 Transplant: May 5 🍅 Harvest: Jun 23 – Jul 28
Recommended (50%) ✓ Fits season (63 days to spare)
Start indoors: Apr 7 Transplant: May 12 🍅 Harvest: Jun 30 – Aug 4
Safe Start (90%) ✓ Fits season (57 days to spare)
Start indoors: Apr 28 Transplant: Jun 2 🍅 Harvest: Jul 21 – Aug 25

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 Kohlrabi's growing requirements.

Soil pH

Your soil pH (7.3–8.5) is more alkaline than Kohlrabi prefers (6.0–7.5). Add sulfur or peat moss to lower pH.

Soil Texture

Sandy soil in San Juan County warms quickly in spring but drains fast. Kohlrabi will need more frequent watering and regular compost additions to retain nutrients.

Drainage

Drainage is adequate for Kohlrabi.

Organic Matter

Organic matter is low (0.9%). Add 2-3 inches of compost before planting Kohlrabi.

How to Plant Kohlrabi

0.5"
Planting Depth
4"
Between Plants
12"
Between Rows

Fall planting: Sow 10 weeks before your first frost date for a fall harvest.

Succession Planting Kohlrabi

3
successive plantings in your 147-day season

Sow every 5.1 weeks. Last sowing by Aug 02 to harvest before frost.

For a dedicated fall crop, sow by Jul 28.

Plant Water Budget

Plant needs
0.7″/week
Rainfall provides
0.4″/week
You supply
0.6″/week
Watering frequency 1-2 times/week
Season total 787 gal / 100 sq ft
Drought risk

Water stress score is 10/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Kohlrabi

Kohlrabi needs approximately 0.7 inches of water per week (3" per month). Here's how your county's rainfall compares month by month.

Month Kohlrabi Needs Rainfall You Supplement Action
Jan 1.1" 0" ❄️ Dormant
Feb 0.8" 0" ❄️ Dormant
Mar 0.8" 0" ❄️ Dormant
Apr 0.5" 0" ❄️ Dormant
May 3" 0.3" 2.7" 🚿 Regular watering
Jun 3" 0.5" 2.5" 🚿 Regular watering
Jul 3" 2.5" 0.5" 💧 Light watering
Aug 3" 2.6" 0.4" 💧 Light watering
Sep 3" 2.2" 0.8" 💧 Light watering
Oct 3" 1.3" 1.7" 🚿 Regular watering
Nov 0.8" 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.

Kohlrabi 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.

Kohlrabi needs ~839 GDD — county provides 2,241 GDD Excellent fit

Kohlrabi Planting Timeline — San Juan County, NM

Kohlrabi Planting Calendar

Activity When Date Range
Start Indoors April 7 Apr 7 – Apr 21
Transplant Outdoors May 12 May 12 – May 26
Direct Sow April 28 Apr 28 – May 19
Harvest June 30 Jun 30 – Aug 4
Fall Sowing July 28 Jul 28 – Aug 11

Plant 0.5" deep · 4" apart · Rows 12" apart

Month-by-Month Timeline

MonthActivities
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

Full Sun (6-8+ hours)

💧 Water

0.7"/week · 1-2 times/week

📅 Days to Maturity

45–65 days

🧪 Soil pH

Needs 6–7.5 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 7a

📆 Growing Season

147 days in San Juan County

Growing Tips for Kohlrabi in San Juan County

Direct sow Kohlrabi outdoors after May 12 in San Juan County when soil has warmed and frost danger has passed.

Sandy soil in San Juan County dries quickly — mulch Kohlrabi with 2-3 inches of straw and water deeply 2-3 times per week rather than lightly every day.

Common pests for Kohlrabi 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 spring or fall. Harvest when bulbs are 2-3 inches in diameter for best texture and flavor. Larger bulbs may become woody and fibrous.

Companion Planting

Good Companions

Avoid Planting Near

  • Tomatoes
  • Strawberries

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Kohlrabi in San Juan County, NM?

San Juan County is in Zone 7a with an average last frost of May 12. Plan your Kohlrabi planting based on this frost date — see the calendar above for exact timing.

What planting zone is San Juan County, NM?

San Juan County, New Mexico is in USDA Hardiness Zone 7a. The average last spring frost is May 12 and first fall frost is October 6.

🌱

Your San Juan County Garden Planner — Free

A 24-page printable planner built for San Juan County (Zone 7a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

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Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for San Juan County, NM. Local conditions may vary. Last updated: May 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.