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When to plant Chard in Bonner County, ID

The best window to plant Chard in Bonner County, is April 21–May 12, when soil warms to 50°F. Last frost typically hits May 5; first frost October 3. A second sowing from July 25 to August 8 extends the harvest into fall.

When to Plant Chard in Bonner County, ID

Bonner County, Idaho Zone 6b June

June in the garden — Bonner County, Idaho

June is a pivotal month for Bonner County, Idaho gardens. Focus on these tasks first and you'll set up the rest of the season for success.

Avg. last frost May 5
Avg. first frost October 3
Soil temp (4") 45°F
Watering Critical
Pest pressure High
Daylight 15.8 hrs
  1. Fire up the seed-starting tray: chard

    These need a head start before your last frost (May 5). Sow into cells now so you're ready to transplant in a few weeks.

  2. Harvest chard as they ripen

    This is the payoff month. Bring a basket, bring a friend, and get into the beds.

Coming up in July — start thinking about
  • First harvests: chard
  • Fall sowing: chard

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Swiss chard is a colorful, heat-tolerant green with large crinkled leaves and vibrant stalks in red, yellow, and white. Both the leaves and stems are edible and nutritious.

Bonner County, Idaho is in USDA Zone 6b. The average last spring frost is May 5 and the first fall frost is October 3, giving you a growing season of approximately 151 days.

At an elevation of 7,480 feet, Bonner County receives approximately 12.9 inches of rainfall annually with predominantly loam soil. Summer highs average 86°F, providing good warmth for Chard during the growing season. With low rainfall, drip irrigation is essential for growing Chard successfully. Mulch heavily to conserve soil moisture.

Bonner County, ID (Zone 6b) Moderate season
151 days
Last Spring Frost May 5
151 growing days
First Fall Frost October 3

Bonner County Soil Profile

Soil Type

Loam

Soil pH

6.4-8.2

Drainage

Well Drained

Chard Planting Risk Windows

Early Start (70% safe) ✓ Fits season (40 days to spare)
Start indoors: Mar 24 Transplant: Apr 28 🍅 Harvest: Jun 23 – Aug 11
Recommended (50%) ✓ Fits season (46 days to spare)
Start indoors: Mar 31 Transplant: May 5 🍅 Harvest: Jun 30 – Aug 18
Safe Start (90%) ✓ Fits season (41 days to spare)
Start indoors: Apr 27 Transplant: Jun 1 🍅 Harvest: Jul 27 – Sep 14

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 Bonner County

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

Soil pH

Your soil pH (6.4–8.2) is more alkaline than Chard prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.4%). Annual compost additions will help Chard.

How to Plant Chard

1"
Planting Depth
15"
Between Plants
24"
Between Rows

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

Succession Planting Chard

3
successive plantings in your 151-day season

Sow every 5.7 weeks. Last sowing by Aug 04 to harvest before frost.

For a dedicated fall crop, sow by Jul 25.

Chard Water Budget

Plant needs
0.8″/week
Rainfall provides
0.4″/week
You supply
0.5″/week
Watering frequency 1-2 times/week
Season total 712 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Chard

Chard needs approximately 0.8 inches of water per week (3.5" per month). Here's how your county's rainfall compares month by month.

Month Chard Needs Rainfall You Supplement Action
Jan 0.9" 0" ❄️ Dormant
Feb 0.7" 0" ❄️ Dormant
Mar 1.1" 0" ❄️ Dormant
Apr 1.5" 0" ❄️ Dormant
May 3.5" 1.5" 2" 🚿 Regular watering
Jun 3.5" 0.9" 2.6" 🚿 Regular watering
Jul 3.5" 1.1" 2.4" 🚿 Regular watering
Aug 3.5" 1.2" 2.3" 🚿 Regular watering
Sep 3.5" 1.1" 2.4" 🚿 Regular watering
Oct 3.5" 1.1" 2.4" 🚿 Regular watering
Nov 0.9" 0" ❄️ Dormant
Dec 0.7" 0" ❄️ Dormant

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

Chard 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.

Chard needs ~798 GDD — county provides 2,189 GDD Excellent fit

Chard Planting Timeline — Bonner County, ID

Chard Planting Calendar

Activity When Date Range
Start Indoors March 31 Mar 31 – Apr 14
Transplant Outdoors May 5 May 5 – May 19
Direct Sow April 21 Apr 21 – May 12
Harvest June 30 Jun 30 – Aug 18
Fall Sowing July 25 Jul 25 – Aug 8

Plant 1" deep · 15" apart · Rows 24" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

0.8"/week · 1-2 times/week

📅 Days to Maturity

50–60 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 6b

📆 Growing Season

151 days in Bonner County

Growing Tips for Chard in Bonner County

Direct sow Chard outdoors after May 05 in Bonner County when soil has warmed and frost danger has passed.

General growing tips

Direct sow or transplant after last frost. Harvest outer leaves regularly to encourage continuous production. Chard tolerates both heat and light frost.

Companion Planting

Good Companions

Avoid Planting Near

  • Corn
  • Cucumbers

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Chard in Bonner County, ID?

Bonner County is in Zone 6b with an average last frost of May 5. Plan your Chard planting based on this frost date — see the calendar above for exact timing.

What planting zone is Bonner County, ID?

Bonner County, Idaho is in USDA Hardiness Zone 6b. The average last spring frost is May 5 and first fall frost is October 3.

When should I plant Chard in Bonner County, ID?

In Bonner County, ID, plant Chard after the last frost (around May 5) and before the first frost (around October 3). Best results when soil holds above 50°F.

What growing zone is Bonner County, ID for Chard?

Bonner County sits in USDA Zone 6b. Chard grows reliably in zones 2a through 11b, so it's a good fit here.

Can Chard grow in Bonner County's climate?

Yes — Chard grows well in Bonner County's temperate climate. Bonner County averages a 151-day frost-free season, with last frost around May 5 and first frost around October 3.

🌱

Your Bonner County Garden Planner — Free

A 22-page printable planner built for Bonner County (Zone 6b). 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 Bonner County, ID. Local conditions may vary. Last updated: June 2026.

Sources & credits

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