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When to plant Crocus in Mahnomen County, MN

Mahnomen County's climate puts the Crocus spring window between mid-spring and late spring. be cautious and check the 10-day forecast before planting tender crops. A second sowing from August 16 to August 30 extends the harvest into fall.

When to Plant Crocus in Mahnomen County, MN

Mahnomen County, Minnesota Zone 4a August

Top priorities for Mahnomen County, Minnesota gardeners in August

A quick August briefing for Mahnomen County, Minnesota gardeners — what's urgent, what's next, and what can wait.

Avg. last frost May 13
Avg. first frost September 27
Soil temp (4") 69°F
Watering Moderate
Pest pressure Moderate
Daylight 14.1 hrs
  1. Start your fall crops: crocus

    Keep young seedlings shaded and moist in summer heat. A row of taller crops works as natural shade.

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Crocuses (Crocus spp.) are the heralds of spring — small, gem-like blooms that push up through frozen ground or even snow, often weeks before any other flower. Their compact corms naturalize readily in lawns, rock gardens, and borders, creating drifts of purple, white, and yellow that expand year after year. Bees prize early crocus as one of their first nectar and pollen sources of the season. The saffron crocus (C. sativus) blooms in fall and yields the world's most expensive spice.

Mahnomen County, Minnesota is in USDA Zone 4a. The average last spring frost is May 13 and the first fall frost is September 27, giving you a growing season of approximately 137 days.

At an elevation of 1,223 feet, Mahnomen County receives approximately 33.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 80°F, so choose short-season varieties of Crocus to ensure they mature before fall.

Bulb Blooms in Spring Pollinator-friendly Fragrant
Mahnomen County, MN (Zone 4a) Short season
137 days
Last Spring Frost May 13
137 growing days
First Fall Frost September 27

Mahnomen County Soil Profile

Soil Type

Silt Loam

Soil pH

5.9-7

Drainage

Well Drained

Crocus Planting Risk Windows

Early Start (70% safe) ✓ Fits season (172 days to spare)
Transplant: May 7 🌸 Bloom: Mar 12 – Apr 2
Recommended (50%) ✓ Fits season (172 days to spare)
Transplant: May 13 🌸 Bloom: Mar 18 – Apr 8
Safe Start (90%) ✓ Fits season (179 days to spare)
Transplant: May 23 🌸 Bloom: Mar 28 – Apr 18

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 Mahnomen County

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

Soil pH

Your soil pH (5.9–7.0) overlaps with Crocus's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Drainage

Drainage is adequate for Crocus.

Organic Matter

Organic matter is excellent (4.0%) — Crocus will thrive.

How to Plant Crocus

4"
Planting Depth
3"
Between Plants
4"
Between Rows

Fall planting: Sow 6 weeks before your first frost date for a fall harvest.

Succession Planting Crocus

16
successive plantings in your 137-day season

Sow every 1.1 weeks. Last sowing by Sep 07 to harvest before frost.

For a dedicated fall crop, sow by Aug 16.

Crocus Water Budget

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

Monthly Watering Guide for Crocus

Crocus needs approximately 0.5 inches of water per week (2.2" per month). Here's how your county's rainfall compares month by month.

Month Crocus Needs Rainfall You Supplement Action
Jan 1.3" 0" ❄️ Dormant
Feb 1.5" 0" ❄️ Dormant
Mar 2.2" 0" ❄️ Dormant
Apr 2.9" 0" ❄️ Dormant
May 2.2" 4.3" 0" ✅ Rainfall sufficient
Jun 2.2" 3.8" 0" ✅ Rainfall sufficient
Jul 2.2" 3.7" 0" ✅ Rainfall sufficient
Aug 2.2" 3.6" 0" ✅ Rainfall sufficient
Sep 2.2" 3.1" 0" ✅ Rainfall sufficient
Oct 2.4" 0" ❄️ Dormant
Nov 2.4" 0" ❄️ Dormant
Dec 2" 0" ❄️ Dormant

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

Crocus 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.

Crocus needs ~150 GDD — county provides 1,370 GDD Excellent fit

Crocus Planting Timeline — Mahnomen County, MN

Crocus Planting Calendar

Activity When Date Range
Bloom June 21 Jun 21 – Jul 12
Fall Sowing August 16 Aug 16 – Aug 30

Plant 4" deep · 3" apart · Rows 4" apart

Month-by-Month Timeline

MonthActivities
January
February
March
April
May
June Bloom
July Bloom
August Fall Sowing
September
October
November
December

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.5"/week · Natural rainfall sufficient

📅 Days to Maturity

10–20 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 4a

📆 Growing Season

137 days in Mahnomen County

Growing Tips for Crocus in Mahnomen County

Direct sow Crocus outdoors after May 13 in Mahnomen County when soil has warmed and frost danger has passed.

Your generous 137.0-day season in Mahnomen County allows multiple plantings of Crocus. Sow every 5.0 days for continuous harvest.

General growing tips

Plant corms 3–4 inches deep and 2–3 inches apart in fall, when soil temperature drops below 60°F. Mass plantings (at least 25 corms per cluster) create the most visual impact. Plant in well-drained soil — corms rot in standing water. Crocus naturalize well under deciduous trees; the tree leafs out after crocus dormancy begins, so light competition is minimal. Squirrels and chipmunks dig corms — plant deeper (4 inches) or use wire mesh baskets in high-predation areas. Allow foliage to die back naturally before mowing lawns. In zones 8a–8b, plant in December with pre-chilled corms for best results.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Crocus in Mahnomen County, MN?

Mahnomen County is in Zone 4a with an average last frost of May 13. Plan your Crocus planting based on this frost date — see the calendar above for exact timing.

What planting zone is Mahnomen County, MN?

Mahnomen County, Minnesota is in USDA Hardiness Zone 4a. The average last spring frost is May 13 and first fall frost is September 27.

When should I plant Crocus in Mahnomen County, MN?

In Mahnomen County, MN, plant Crocus after the last frost (around May 13) and before the first frost (around September 27). Best results when soil holds above 50°F.

What growing zone is Mahnomen County, MN for Crocus?

Mahnomen County sits in USDA Zone 4a. Crocus grows reliably in zones 3a through 8b, so it's a good fit here.

Can Crocus grow in Mahnomen County's climate?

Yes — Crocus grows well in Mahnomen County's temperate climate. Mahnomen County averages a 137-day frost-free season, with last frost around May 13 and first frost around September 27.

🌱

Your Mahnomen County Garden Planner — Free

A 22-page printable planner built for Mahnomen 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 Mahnomen County, MN. Local conditions may vary. Last updated: August 2026.

Sources & credits

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