When to Plant Rhubarb in Kootenai County, ID
May to-do list for Kootenai County, Idaho
If you only do a handful of things in the garden this May, make it these. They're sequenced around your zone's frost timing.
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Get rhubarb in the ground
Harden off for 7 days — a little more sun each day — before planting. That's the difference between a seedling that thrives and one that stalls.
Rhubarb is a long-lived perennial vegetable grown for its tart, colorful stalks. Only the stalks are edible as the leaves contain toxic oxalic acid.
Kootenai County, Idaho is in USDA Zone 6b. The average last spring frost is April 29 and the first fall frost is October 8, giving you a growing season of approximately 162 days.
At an elevation of 5,986 feet, Kootenai County receives approximately 20.7 inches of rainfall annually with predominantly loam soil. Summer highs average 86°F, providing good warmth for Rhubarb during the growing season.
Kootenai County Soil Profile
Soil Type
Loam
Soil pH
6.7-7.7
Drainage
Well Drained
Plant Planting Risk Windows
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 Kootenai County
How your county's soil matches Rhubarb's growing requirements.
Soil pH
Your soil pH (6.7–7.7) is more alkaline than Rhubarb prefers (6.0–7.0). Add sulfur or peat moss to lower pH.
Soil Texture
The loam soil in Kootenai County is excellent for Rhubarb — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (2.3%). Annual compost additions will help Rhubarb.
How to Plant Rhubarb
Plant Water Budget
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Rhubarb
Rhubarb needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Rhubarb Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.5" | 0" | ❄️ Dormant |
| Feb | — | 1.2" | 0" | ❄️ Dormant |
| Mar | — | 1.7" | 0" | ❄️ Dormant |
| Apr | 4.3" | 2.4" | 1.9" | 💧 Light watering |
| May | 4.3" | 2.7" | 1.6" | 💧 Light watering |
| Jun | 4.3" | 1.3" | 3" | 🚿 Regular watering |
| Jul | 4.3" | 1.9" | 2.4" | 🚿 Regular watering |
| Aug | 4.3" | 2" | 2.3" | 🚿 Regular watering |
| Sep | 4.3" | 1.9" | 2.4" | 🚿 Regular watering |
| Oct | 4.3" | 1.5" | 2.8" | 🚿 Regular watering |
| Nov | — | 1.3" | 0" | ❄️ Dormant |
| Dec | — | 1.3" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Kootenai County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Rhubarb 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.
Rhubarb Planting Timeline — Kootenai County, ID
Rhubarb Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | May 20 | May 20 – Jun 3 |
Plant 1" deep · 30" apart · Rows 42" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | — |
| May | Transplant Outdoors |
| June | Transplant Outdoors |
| July | — |
| August | — |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1"/week · 1-2 times/week
📅 Days to Maturity
365–730 days
🧪 Soil pH
Needs 6–7 · Your soil: too_alkaline
🗺️ USDA Zone
Zone 6b
📆 Growing Season
162 days in Kootenai County
Growing Tips for Rhubarb in Kootenai County
Direct sow Rhubarb outdoors after April 29 in Kootenai County when soil has warmed and frost danger has passed.
Your 162.0-day growing season in Kootenai County is tight for Rhubarb (365.0-730.0 days to maturity). Start indoors and choose early-maturing varieties.
Kootenai County receives only 21" of rain annually. Rhubarb needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.
General growing tips
Plant crowns in early spring in rich, well-drained soil. Do not harvest stalks the first year. Pull (do not cut) stalks at harvest to avoid introducing rot.
Companion Planting
Good Companions
Check more plant combinations with our Companion Planting Checker →
Rhubarb in Other Locations
Frequently Asked Questions
When should I plant Rhubarb in Kootenai County, ID?
Kootenai County is in Zone 6b with an average last frost of April 29. Plan your Rhubarb planting based on this frost date — see the calendar above for exact timing.
What planting zone is Kootenai County, ID?
Kootenai County, Idaho is in USDA Hardiness Zone 6b. The average last spring frost is April 29 and first fall frost is October 8.
Your Kootenai County Garden Planner — Free
A 24-page printable planner built for Kootenai 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.