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When to plant Tatsoi in Summit County, CO

In Zone 5a (Summit County), direct-sow Tatsoi between June 2 and June 23 for spring, after the June 16 last-frost mark. A second sowing from June 26 to July 10 extends the harvest into fall.

When to Plant Tatsoi in Summit County, CO

Summit County, Colorado Zone 5a July

July in the garden — Summit County, Colorado

Each item below is timed to Summit County, Colorado's frost dates and soil temperatures. Skip nothing, stress about nothing.

Avg. last frost June 16
Avg. first frost September 4
Soil temp (4") 51°F
Watering High
Pest pressure High
Daylight 14.5 hrs
  1. Start tatsoi under lights

    These need a head start before your last frost (June 16). Sow into cells now so you're ready to transplant in a few weeks.

  2. Pick tatsoi

    Check every 1–2 days. Many of these get tough or go to seed if you wait too long.

To set up a strong August, finish these tasks
  • First harvests: tatsoi

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Tatsoi is a compact Asian green forming beautiful rosettes of dark, spoon-shaped leaves with a mild mustard flavor. It is extremely cold-hardy and versatile.

Summit County, Colorado is in USDA Zone 5a. 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 81°F, so choose short-season varieties of Tatsoi to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Tatsoi successfully. Mulch heavily to conserve soil moisture.

Summit County, CO (Zone 5a) 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

Tatsoi Planting Risk Windows

Early Start (70% safe) ✓ Fits season (8 days to spare)
Start indoors: May 6 Transplant: Jun 10 🍅 Harvest: Jul 15 – Aug 19
Recommended (50%) ✓ Fits season (10 days to spare)
Start indoors: May 12 Transplant: Jun 16 🍅 Harvest: Jul 21 – Aug 25
Safe Start (90%) ✓ Fits season (16 days to spare)
Start indoors: May 22 Transplant: Jun 26 🍅 Harvest: Jul 31 – Sep 4

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 Summit County

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

Soil pH

Your soil pH (6.8–8.0) overlaps with Tatsoi's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Drainage

Drainage is adequate for Tatsoi.

Organic Matter

Organic matter is moderate (2.1%). Annual compost additions will help Tatsoi.

How to Plant Tatsoi

0.5"
Planting Depth
6"
Between Plants
12"
Between Rows

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

Succession Planting Tatsoi

2
successive plantings in your 80-day season

Sow every 4 weeks. Last sowing by Jul 16 to harvest before frost.

For a dedicated fall crop, sow by Jun 26.

Tatsoi 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 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Tatsoi

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

Month Tatsoi Needs Rainfall You Supplement Action
Jan 1.4" 0" ❄️ Dormant
Feb 1.1" 0" ❄️ Dormant
Mar 1.6" 0" ❄️ Dormant
Apr 1.7" 0" ❄️ Dormant
May 1.8" 0" ❄️ Dormant
Jun 4.3" 1.3" 3" 🚿 Regular watering
Jul 4.3" 1.5" 2.8" 🚿 Regular watering
Aug 4.3" 1.9" 2.4" 🚿 Regular watering
Sep 4.3" 1.3" 3" 🚿 Regular watering
Oct 1.6" 0" ❄️ Dormant
Nov 1.2" 0" ❄️ Dormant
Dec 1.2" 0" ❄️ Dormant

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

Tatsoi 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.

Tatsoi needs ~457 GDD — county provides 860 GDD Excellent fit

Tatsoi Planting Timeline — Summit County, CO

Tatsoi Planting Calendar

Activity When Date Range
Start Indoors May 12 May 12 – May 26
Transplant Outdoors June 16 Jun 16 – Jun 30
Direct Sow June 2 Jun 2 – Jun 23
Harvest July 21 Jul 21 – Aug 25
Fall Sowing June 26 Jun 26 – Jul 10

Plant 0.5" deep · 6" apart · Rows 12" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · 1-2 times/week

📅 Days to Maturity

35–50 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 5a

📆 Growing Season

80 days in Summit County

Growing Tips for Tatsoi in Summit County

Direct sow Tatsoi outdoors after June 16 in Summit County when soil has warmed and frost danger has passed.

Common pests for Tatsoi in this region include cabbage worm and flea beetles. Use row covers early in the season and inspect plants weekly.

Summit County receives only 18" of rain annually. Tatsoi needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Direct sow in spring or fall. Tatsoi tolerates frost down to 15F. Harvest outer leaves or cut whole rosettes. Excellent in salads, stir-fries, or lightly wilted.

Companion Planting

Good Companions

Avoid Planting Near

  • Strawberries

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Tatsoi in Summit County, CO?

Summit County is in Zone 5a with an average last frost of June 16. Plan your Tatsoi planting based on this frost date — see the calendar above for exact timing.

What planting zone is Summit County, CO?

Summit County, Colorado is in USDA Hardiness Zone 5a. The average last spring frost is June 16 and first fall frost is September 4.

When should I plant Tatsoi in Summit County, CO?

In Summit County, CO, plant Tatsoi after the last frost (around June 16) and before the first frost (around September 4). Best results when soil holds above 50°F.

What growing zone is Summit County, CO for Tatsoi?

Summit County sits in USDA Zone 5a. Tatsoi grows reliably in zones 2a through 11b, so it's a good fit here.

Can Tatsoi grow in Summit County's climate?

Yes — Tatsoi grows well in Summit County's temperate climate. Summit County averages a 80-day frost-free season, with last frost around June 16 and first frost around September 4.

🌱

Your Summit County Garden Planner — Free

A 22-page printable planner built for Summit County (Zone 5a). 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 Summit County, CO. Local conditions may vary. Last updated: July 2026.

Sources & credits

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