Blog

When to Plant Mache in Jefferson County, MT

Jefferson County, Montana Zone 4b April

April in Jefferson County, Montana — your action list

Here's what deserves your attention in Jefferson County, Montana this month. Everything below is tailored to Zone 4b and timed around your local frost dates.

Avg. last frost June 15
Avg. first frost September 7
Soil temp (4") 17°F
Watering High
Pest pressure Low
Daylight 13.3 hrs

Instant PDF download. No spam, unsubscribe any time.

Mache (corn salad) is a cold-hardy salad green with small, rounded, tender leaves and a mild, nutty flavor. It thrives in cool weather and even overwinters in many climates.

Jefferson County, Montana is in USDA Zone 4b. The average last spring frost is June 15 and the first fall frost is September 7, giving you a growing season of approximately 84 days.

At an elevation of 7,214 feet, Jefferson County receives approximately 21.5 inches of rainfall annually with predominantly loam soil. Summer highs average 82°F, so choose short-season varieties of Mache to ensure they mature before fall.

Jefferson County, MT (Zone 4b) Very short season
84 days
Last Spring Frost June 15
84 growing days
First Fall Frost September 7

Jefferson County Soil Profile

Soil Type

Loam

Soil pH

6.4-7.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (8 days to spare)
Start indoors: Apr 28 Transplant: Jun 9 🍅 Harvest: Jul 21 – Aug 25
Recommended (50%) ✓ Fits season (7 days to spare)
Start indoors: May 4 Transplant: Jun 15 🍅 Harvest: Jul 27 – Aug 31
Safe Start (90%) ✓ Fits season (13 days to spare)
Start indoors: May 12 Transplant: Jun 23 🍅 Harvest: Aug 4 – Sep 8

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 Jefferson County

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

Soil pH

Your soil pH (6.4–7.9) overlaps with Mache's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Drainage

Drainage is adequate for Mache.

Organic Matter

Organic matter is moderate (2.5%). Annual compost additions will help Mache.

How to Plant Mache

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

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

Succession Planting Mache

2
successive plantings in your 84-day season

Sow every 4.6 weeks. Last sowing by Jul 09 to harvest before frost.

For a dedicated fall crop, sow by Jun 15.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
1.1″/week
You supply
0.3″/week
Watering frequency Only during dry spells
Season total 202 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Mache

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

Month Mache Needs Rainfall You Supplement Action
Jan 1.5" 0" ❄️ Dormant
Feb 1.4" 0" ❄️ Dormant
Mar 2" 0" ❄️ Dormant
Apr 2" 0" ❄️ Dormant
May 2.5" 0" ❄️ Dormant
Jun 4.3" 1.5" 2.8" 🚿 Regular watering
Jul 4.3" 2" 2.3" 🚿 Regular watering
Aug 4.3" 2" 2.3" 🚿 Regular watering
Sep 4.3" 2" 2.3" 🚿 Regular watering
Oct 1.8" 0" ❄️ Dormant
Nov 1.4" 0" ❄️ Dormant
Dec 1.4" 0" ❄️ Dormant

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

Mache 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.

Mache needs ~575 GDD — county provides 966 GDD Excellent fit

Mache Planting Timeline — Jefferson County, MT

Mache Planting Calendar

Activity When Date Range
Start Indoors May 4 May 4 – May 18
Transplant Outdoors June 15 Jun 15 – Jun 29
Direct Sow June 8 Jun 8 – Jun 29
Harvest July 27 Jul 27 – Aug 31
Fall Sowing June 15 Jun 15 – Jun 29

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 Harvest
August Harvest
September
October
November
December

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

40–60 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 4b

📆 Growing Season

84 days in Jefferson County

Growing Tips for Mache in Jefferson County

Direct sow Mache outdoors after June 15 in Jefferson County when soil has warmed and frost danger has passed.

Jefferson County receives only 22" of rain annually. Mache needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Direct sow in early spring or late summer for fall and winter harvest. Seeds need light to germinate so press gently into soil surface. Harvest whole rosettes.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Mache in Jefferson County, MT?

Jefferson County is in Zone 4b with an average last frost of June 15. Plan your Mache planting based on this frost date — see the calendar above for exact timing.

What planting zone is Jefferson County, MT?

Jefferson County, Montana is in USDA Hardiness Zone 4b. The average last spring frost is June 15 and first fall frost is September 7.

🌱

Your Jefferson County Garden Planner — Free

A 24-page printable planner built for Jefferson 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.

Instant PDF download. No spam, unsubscribe any time.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Jefferson County, MT. Local conditions may vary. Last updated: April 2026.

Sources & credits

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