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When to Plant Kohlrabi in Dewey County, SD

Dewey County, South Dakota Zone 4b May

May to-do list for Dewey County, South Dakota

A quick May briefing for Dewey County, South Dakota gardeners — what's urgent, what's next, and what can wait.

Avg. last frost May 11
Avg. first frost October 3
Soil temp (4") 56°F
Watering Moderate
Pest pressure Low
Daylight 14.7 hrs
  1. Plant out kohlrabi

    Bring a watering can to the bed. Each transplant gets a drink the moment it's in the ground, not ten minutes later.

  2. Scatter kohlrabi into prepared beds

    These tolerate cool soil, so you're not gambling by sowing now.

Get ahead of June
  • 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.

Dewey County, South Dakota is in USDA Zone 4b. The average last spring frost is May 11 and the first fall frost is October 3, giving you a growing season of approximately 145 days.

At an elevation of 1,004 feet, Dewey County receives approximately 25.2 inches of rainfall annually with predominantly loam soil. Summer highs average 84°F, so choose short-season varieties of Kohlrabi to ensure they mature before fall.

Dewey County, SD (Zone 4b) Short season
145 days
Last Spring Frost May 11
145 growing days
First Fall Frost October 3

Dewey County Soil Profile

Soil Type

Loam

Soil pH

6.2-7.6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (64 days to spare)
Start indoors: Mar 21 Transplant: May 2 🍅 Harvest: Jun 20 – Jul 25
Recommended (50%) ✓ Fits season (61 days to spare)
Start indoors: Mar 30 Transplant: May 11 🍅 Harvest: Jun 29 – Aug 3
Safe Start (90%) ✓ Fits season (66 days to spare)
Start indoors: Apr 7 Transplant: May 19 🍅 Harvest: Jul 7 – Aug 11

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 Dewey County

How your county's soil matches Kohlrabi's growing requirements.

Soil pH

Your soil pH (6.2–7.6) overlaps with Kohlrabi's range (6.0–7.5), though not a perfect match.

Soil Texture

The loam soil in Dewey County is excellent for Kohlrabi — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (3.9%). Annual compost additions will help Kohlrabi.

How to Plant Kohlrabi

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

Fall planting: Sow 12 weeks before your first frost date for a fall harvest.

Succession Planting Kohlrabi

3
successive plantings in your 145-day season

Sow every 5.1 weeks. Last sowing by Jul 30 to harvest before frost.

For a dedicated fall crop, sow by Jul 11.

Plant Water Budget

Plant needs
0.7″/week
Rainfall provides
0.7″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — 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 1.5" 0" ❄️ Dormant
Feb 1.3" 0" ❄️ Dormant
Mar 2" 0" ❄️ Dormant
Apr 2.9" 0" ❄️ Dormant
May 3" 3.3" 0" ✅ Rainfall sufficient
Jun 3" 1.8" 1.2" 💧 Light watering
Jul 3" 2.1" 0.9" 💧 Light watering
Aug 3" 2.8" 0.2" 💧 Light watering
Sep 3" 2.3" 0.7" 💧 Light watering
Oct 3" 2.3" 0.7" 💧 Light watering
Nov 1.5" 0" ❄️ Dormant
Dec 1.4" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Dewey 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 ~715 GDD — county provides 1,885 GDD Excellent fit

Kohlrabi Planting Timeline — Dewey County, SD

Kohlrabi Planting Calendar

Activity When Date Range
Start Indoors March 30 Mar 30 – Apr 13
Transplant Outdoors May 11 May 11 – May 25
Direct Sow May 4 May 4 – May 25
Harvest June 29 Jun 29 – Aug 3
Fall Sowing July 11 Jul 11 – Jul 25

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

Month-by-Month Timeline

MonthActivities
January
February
March Start Indoors
April Start Indoors
May Transplant Outdoors Direct Sow
June Harvest
July Fall Sowing Harvest
August Harvest
September
October
November
December

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.7"/week · Natural rainfall sufficient

📅 Days to Maturity

45–65 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 4b

📆 Growing Season

145 days in Dewey County

Growing Tips for Kohlrabi in Dewey County

Direct sow Kohlrabi outdoors after May 11 in Dewey County when soil has warmed and frost danger has passed.

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 Dewey County, SD?

Dewey County is in Zone 4b with an average last frost of May 11. Plan your Kohlrabi planting based on this frost date — see the calendar above for exact timing.

What planting zone is Dewey County, SD?

Dewey County, South Dakota is in USDA Hardiness Zone 4b. The average last spring frost is May 11 and first fall frost is October 3.

🌱

Your Dewey County Garden Planner — Free

A 24-page printable planner built for Dewey County (Zone 4b). 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 Dewey County, SD. 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.