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When to Plant Shallot in Summit County, CO

Shallots are a gourmet allium prized for their complex, sweet, and mild flavor. Each bulb multiplies into a cluster, making them easy and rewarding to grow.

Summit County, Colorado is in USDA Zone 4a. The average last spring frost is June 16 and the first fall frost is September 4, giving you a growing season of approximately 80 days.

At an elevation of 7,005 feet, Summit County receives approximately 17.5 inches of rainfall annually with predominantly loam soil. Summer highs average 81ยฐF, so choose short-season varieties of Shallot to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Shallot successfully. Mulch heavily to conserve soil moisture.

Summit County, CO (Zone 4a) Very short season
80 days
Last Spring Frost June 16
80 growing days
First Fall Frost September 4

Summit County Soil Profile

Soil Type

Loam

Soil pH

6.8-8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Apr 29 Transplant: Jun 10 🍅 Harvest: Sep 9 – Oct 28
Recommended (50%) ✗ May not fit
Start indoors: May 5 Transplant: Jun 16 🍅 Harvest: Sep 15 – Nov 3
Safe Start (90%) ✗ May not fit
Start indoors: May 15 Transplant: Jun 26 🍅 Harvest: Sep 25 – Nov 13

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.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.9″/week
You supply
0.5″/week
Watering frequency 1-2 times/week
Season total 326 gal / 100 sq ft
Drought risk

Water stress score is 8/10 โ€” consider drought-tolerant varieties and mulching

Shallot needs ~1,129 GDD — county provides 860 GDD May not mature

Shallot Planting Timeline โ€” Summit County, CO

Shallot Planting Calendar

Activity When Date Range
Start Indoors May 5 May 5 โ€“ May 19
Transplant Outdoors June 16 Jun 16 โ€“ Jun 30
Direct Sow June 9 Jun 9 โ€“ Jun 30
Fall Sowing June 12 Jun 12 โ€“ Jun 26
Harvest September 15 Sep 15 โ€“ Nov 3

Plant 1" deep ยท 6" apart ยท Rows 12" apart

Month-by-Month Timeline

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

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

90โ€“120 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 4a

Growing Season

80 days

Growing Tips for Summit County

Plant sets in fall for spring harvest or early spring for summer harvest. Mulch heavily if overwintering. Harvest when tops brown and dry, then cure for storage.

Companion Planting

Good Companions

Avoid Planting Near

  • Peas
  • Green Beans

Level Up Your Garden

Frequently Asked Questions

When should I plant Shallot in Summit County, CO?

Summit County is in Zone 4a with an average last frost of June 16. Plan your Shallot planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Summit County, CO?

Summit County, Colorado is in USDA Hardiness Zone 4a. The average last spring frost is June 16 and first fall frost is September 4.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Summit County gardeners in Zone 4a organize planting dates, track what's growing, and never miss a planting window.

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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 Summit County, CO. Local conditions may vary. Last updated: April 2026.