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When to Plant Rhubarb in Aitkin County, MN

Aitkin County, Minnesota Zone 4a May

This month in Aitkin County, Minnesota

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

Avg. last frost May 9
Avg. first frost October 3
Soil temp (4") 48°F
Watering Moderate
Pest pressure Low
Daylight 14.8 hrs
Looking ahead to June
  • Transplants going out: rhubarb

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Rhubarb is a long-lived perennial vegetable grown for its tart, colorful stalks. Only the stalks are edible as the leaves contain toxic oxalic acid.

Aitkin County, Minnesota is in USDA Zone 4a. The average last spring frost is May 9 and the first fall frost is October 3, giving you a growing season of approximately 147 days.

At an elevation of 1,188 feet, Aitkin County receives approximately 35 inches of rainfall annually with predominantly silt loam soil. Summer highs average 78°F, so choose short-season varieties of Rhubarb to ensure they mature before fall.

Aitkin County, MN (Zone 4a) Short season
147 days
Last Spring Frost May 9
147 growing days
First Fall Frost October 3

Aitkin County Soil Profile

Soil Type

Silt Loam

Soil pH

5.8-7.1

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season
Transplant: May 29
Recommended (50%) ✓ Fits season
Transplant: Jun 6
Safe Start (90%) ✓ Fits season
Transplant: Jun 23

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 Aitkin County

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

Soil pH

Your soil pH (5.8–7.1) overlaps with Rhubarb's range (6.0–7.0), though not a perfect match.

Soil Texture

The silt loam soil in Aitkin County is excellent for Rhubarb — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is excellent (4.9%) — Rhubarb will thrive.

How to Plant Rhubarb

1"
Planting Depth
30"
Between Plants
42"
Between Rows

Plant Water Budget

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

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Rhubarb

Rhubarb needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Rhubarb Needs Rainfall You Supplement Action
Jan 1.4" 0" ❄️ Dormant
Feb 1.5" 0" ❄️ Dormant
Mar 2.6" 0" ❄️ Dormant
Apr 3.6" 0" ❄️ Dormant
May 4.3" 3.7" 0.6" 💧 Light watering
Jun 4.3" 5.1" 0" ✅ Rainfall sufficient
Jul 4.3" 3.9" 0.4" 💧 Light watering
Aug 4.3" 3.5" 0.8" 💧 Light watering
Sep 4.3" 2.8" 1.5" 💧 Light watering
Oct 4.3" 2.7" 1.6" 💧 Light watering
Nov 2.4" 0" ❄️ Dormant
Dec 1.9" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Aitkin County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Rhubarb 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.

Rhubarb needs ~4,654 GDD — county provides 1,249 GDD May not mature

Rhubarb Planting Timeline — Aitkin County, MN

Rhubarb Planting Calendar

Activity When Date Range
Transplant Outdoors June 6 Jun 6 – Jun 20

Plant 1" deep · 30" apart · Rows 42" apart

Month-by-Month Timeline

MonthActivities
January
February
March
April
May
June Transplant Outdoors
July
August
September
October
November
December

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Natural rainfall sufficient

📅 Days to Maturity

365–730 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 4a

📆 Growing Season

147 days in Aitkin County

Growing Tips for Rhubarb in Aitkin County

Direct sow Rhubarb outdoors after May 09 in Aitkin County when soil has warmed and frost danger has passed.

Your 147.0-day growing season in Aitkin County is tight for Rhubarb (365.0-730.0 days to maturity). Start indoors and choose early-maturing varieties.

General growing tips

Plant crowns in early spring in rich, well-drained soil. Do not harvest stalks the first year. Pull (do not cut) stalks at harvest to avoid introducing rot.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Rhubarb in Aitkin County, MN?

Aitkin County is in Zone 4a with an average last frost of May 9. Plan your Rhubarb planting based on this frost date — see the calendar above for exact timing.

What planting zone is Aitkin County, MN?

Aitkin County, Minnesota is in USDA Hardiness Zone 4a. The average last spring frost is May 9 and first fall frost is October 3.

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Your Aitkin County Garden Planner — Free

A 24-page printable planner built for Aitkin County (Zone 4a). 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 Aitkin County, MN. 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.