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When to Plant Valerian in Adams County, ID

Adams County, Idaho Zone 6a May

This month in Adams County, Idaho

Welcome to May in Zone 6a. These are the moves that will have the biggest impact on your growing season.

Avg. last frost May 20
Avg. first frost September 25
Soil temp (4") 39°F
Watering High
Pest pressure Low
Daylight 14.6 hrs
  1. Move valerian from tray to bed

    Water the tray well an hour before you transplant. Roots slide out cleanly and settle in faster.

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Valerian is a tall perennial herb with fragrant white or pink flower clusters, valued for its root which is used as a natural sleep aid. It attracts pollinators and earthworms.

Adams County, Idaho is in USDA Zone 6a. The average last spring frost is May 20 and the first fall frost is September 25, giving you a growing season of approximately 128 days.

At an elevation of 6,593 feet, Adams County receives approximately 20.6 inches of rainfall annually with predominantly loam soil. Summer highs average 85°F, providing good warmth for Valerian during the growing season.

Adams County, ID (Zone 6a) Short season
128 days
Last Spring Frost May 20
128 growing days
First Fall Frost September 25
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Adams County Soil Profile

Soil Type

Loam

Soil pH

6.3-8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: May 12 🍅 Harvest: Sep 15 – Nov 24
Recommended (50%) ✗ May not fit
Transplant: May 27 🍅 Harvest: Sep 30 – Dec 9
Safe Start (90%) ✓ Fits season (286 days to spare)
Transplant: Jun 30 🍅 Harvest: Nov 3 – Jan 12

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 Adams County

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

Soil pH

Your soil pH (6.3–8.0) is more alkaline than Valerian prefers (5.5–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Drainage

Drainage is adequate for Valerian.

Organic Matter

Organic matter is moderate (2.2%). Annual compost additions will help Valerian.

How to Plant Valerian

0.5"
Planting Depth
8"
Between Plants
12"
Between Rows

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.7″/week
You supply
0.8″/week
Watering frequency 2-3 times/week
Season total 853 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Valerian

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

Month Valerian Needs Rainfall You Supplement Action
Jan 1.4" 0" ❄️ Dormant
Feb 1.1" 0" ❄️ Dormant
Mar 1.9" 0" ❄️ Dormant
Apr 2" 0" ❄️ Dormant
May 4.3" 2.6" 1.7" 💧 Light watering
Jun 4.3" 1.4" 2.9" 🚿 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 1.8" 0" ❄️ Dormant
Nov 1.4" 0" ❄️ Dormant
Dec 1.2" 0" ❄️ Dormant

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

Valerian 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.

Valerian needs ~2,062 GDD — county provides 1,760 GDD May not mature

Valerian Planting Timeline — Adams County, ID

Valerian Planting Calendar

Activity When Date Range
Transplant Outdoors May 27 May 27 – Jun 10
Harvest September 30 Sep 30 – Dec 9

Plant 0.5" deep · 8" apart · Rows 12" apart

Month-by-Month Timeline

MonthActivities
January
February
March
April
May Transplant Outdoors
June Transplant Outdoors
July
August
September Harvest
October Harvest
November Harvest
December Harvest
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Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · 2-3 times/week

📅 Days to Maturity

120–180 days

🧪 Soil pH

Needs 5.5–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 6a

📆 Growing Season

128 days in Adams County

Growing Tips for Valerian in Adams County

Direct sow Valerian outdoors after May 20 in Adams County when soil has warmed and frost danger has passed.

Your 128.0-day growing season in Adams County is tight for Valerian (120.0-180.0 days to maturity). Start indoors and choose early-maturing varieties.

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

General growing tips

Start seeds indoors and transplant after last frost. Harvest roots in fall of the second year. Deadhead flowers unless you want self-seeding. Cats are attracted to valerian root.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Valerian in Adams County, ID?

Adams County is in Zone 6a with an average last frost of May 20. Plan your Valerian planting based on this frost date — see the calendar above for exact timing.

What planting zone is Adams County, ID?

Adams County, Idaho is in USDA Hardiness Zone 6a. The average last spring frost is May 20 and first fall frost is September 25.

🌱

Your Adams County Garden Planner — Free

A 24-page printable planner built for Adams County (Zone 6a). 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 Adams County, ID. Local conditions may vary. Last updated: May 2026.

Sources & credits

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