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When to plant Snapdragon in Custer County County,

In Custer County County, Snapdragon is a spring-only crop. Plant June 4–June 25 once soil hits 50°F.

When to Plant Snapdragon in Custer County, ID

Custer County, Idaho Zone 5b June

June to-do list for Custer County, Idaho

A quick June briefing for Custer County, Idaho gardeners — what's urgent, what's next, and what can wait.

Avg. last frost June 18
Avg. first frost September 5
Soil temp (4") 51°F
Watering High
Pest pressure High
Daylight 15.3 hrs
  1. Move snapdragon into the garden

    Pick a cloudy afternoon or evening to plant. Less transplant shock, and your seedlings will barely blink.

  2. Scatter snapdragon into prepared beds

    Sow every 2 weeks for a continuous harvest. A single big planting means a single big glut.

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Snapdragons (Antirrhinum majus) are classic cool-season annuals whose upright spikes of dragon-lipped flowers are among spring's most dramatic displays. Tolerating light frosts, they bloom from early spring until summer heat shuts them down — then often revive in fall. In zones 9-11 they are grown as fall-planted winter annuals and may re-seed to naturalize.

Custer County, Idaho is in USDA Zone 5b. The average last spring frost is June 18 and the first fall frost is September 5, giving you a growing season of approximately 79 days.

At an elevation of 5,189 feet, Custer County receives approximately 20.6 inches of rainfall annually with predominantly loam soil. Summer highs average 80°F, so choose short-season varieties of Snapdragon to ensure they mature before fall.

Annual Blooms in Spring Pollinator-friendly Deer-resistant Good for cutting Fragrant
Custer County, ID (Zone 5b) Very short season
79 days
Last Spring Frost June 18
79 growing days
First Fall Frost September 5

Custer County Soil Profile

Soil Type

Loam

Soil pH

6.3-8

Drainage

Well Drained

Snapdragon Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Apr 2 Transplant: Jun 11 🌸 Bloom: Aug 20 – Oct 29
Recommended (50%) ✗ May not fit
Start indoors: Apr 9 Transplant: Jun 18 🌸 Bloom: Aug 27 – Nov 5
Safe Start (90%) ✗ May not fit
Start indoors: Apr 20 Transplant: Jun 29 🌸 Bloom: Sep 7 – Nov 16

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 Custer County

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

Soil pH

Your soil pH (6.3–8.0) is more alkaline than Snapdragon prefers (6.2–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.3%). Annual compost additions will help Snapdragon.

How to Plant Snapdragon

9"
Between Plants
12"
Between Rows

Snapdragon Water Budget

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

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Snapdragon

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

Month Snapdragon Needs Rainfall You Supplement Action
Jan 1.3" 0" ❄️ Dormant
Feb 1.3" 0" ❄️ Dormant
Mar 1.7" 0" ❄️ Dormant
Apr 2.4" 0" ❄️ Dormant
May 2.3" 0" ❄️ Dormant
Jun 4.3" 1.5" 2.8" 🚿 Regular watering
Jul 4.3" 2" 2.3" 🚿 Regular watering
Aug 4.3" 2.1" 2.2" 🚿 Regular watering
Sep 4.3" 1.7" 2.6" 🚿 Regular watering
Oct 1.6" 0" ❄️ Dormant
Nov 1.4" 0" ❄️ Dormant
Dec 1.2" 0" ❄️ Dormant

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

Snapdragon 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.

Snapdragon needs ~850 GDD — county provides 790 GDD Tight fit

Snapdragon Planting Timeline — Custer County, ID

Snapdragon Planting Calendar

Activity When Date Range
Start Indoors April 9 Apr 9 – Apr 23
Transplant Outdoors June 18 Jun 18 – Jul 2
Direct Sow June 4 Jun 4 – Jun 25
Bloom August 27 Aug 27 – Nov 5

· 9" apart · Rows 12" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Natural rainfall sufficient

📅 Days to Maturity

70–100 days

🧪 Soil pH

Needs 6.2–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 5b

📆 Growing Season

79 days in Custer County

Growing Tips for Snapdragon in Custer County

Direct sow Snapdragon outdoors after June 18 in Custer County when soil has warmed and frost danger has passed.

Your 79.0-day growing season in Custer County is tight for Snapdragon (70.0-100.0 days to maturity). Start indoors and choose early-maturing varieties.

Custer County receives only 21" of rain annually. Snapdragon needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Start indoors 10-12 weeks before last frost; seeds need light to germinate — press into moist medium and do not cover. Transplant after hardening off, even if light frosts remain. Pinch seedlings once to encourage branching. Deadhead to prolong blooming. In zones 8-11, sow in fall for a winter-to-spring show. Tall varieties (24-36") make excellent cut flowers.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Snapdragon in Custer County, ID?

Custer County is in Zone 5b with an average last frost of June 18. Plan your Snapdragon planting based on this frost date — see the calendar above for exact timing.

What planting zone is Custer County, ID?

Custer County, Idaho is in USDA Hardiness Zone 5b. The average last spring frost is June 18 and first fall frost is September 5.

When should I plant Snapdragon in Custer County, ?

In Custer County, , plant Snapdragon after the last frost (around June 18) and before the first frost (around September 5). Best results when soil holds above 50°F.

What growing zone is Custer County, for Snapdragon?

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

Can Snapdragon grow in Custer County's climate?

Yes — Snapdragon grows well in Custer County's temperate climate. Custer County averages a 79-day frost-free season, with last frost around June 18 and first frost around September 5.

🌱

Your Custer County Garden Planner — Free

A 22-page printable planner built for Custer County (Zone 5b). 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 Custer 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.