When to Plant Rhubarb in Shoshone County, ID
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.
Shoshone County, Idaho is in USDA Zone 5a. The average last spring frost is May 10 and the first fall frost is September 26, giving you a growing season of approximately 139 days.
At an elevation of 6,353 feet, Shoshone County receives approximately 14.1 inches of rainfall annually with predominantly loam soil. Summer highs average 84°F, so choose short-season varieties of Rhubarb to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Rhubarb successfully. Mulch heavily to conserve soil moisture.
Shoshone County Soil Profile
Soil Type
Loam
Soil pH
6.6-7.7
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 Shoshone County
How your county's soil matches Rhubarb's growing requirements.
Soil pH
Your soil pH (6.6–7.7) is more alkaline than Rhubarb prefers (6.0–7.0). Add sulfur or peat moss to lower pH.
Soil Texture
The loam soil in Shoshone County is excellent for Rhubarb — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Drainage is adequate for Rhubarb.
Organic Matter
Organic matter is moderate (2.8%). Annual compost additions will help Rhubarb.
How to Plant Rhubarb
Plant Water Budget
Water stress score is 8/10 — 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" | 0" | ❄️ Dormant |
| Feb | — | 0.7" | 0" | ❄️ Dormant |
| Mar | — | 1.2" | 0" | ❄️ Dormant |
| Apr | — | 1.3" | 0" | ❄️ Dormant |
| May | 4.3" | 1.9" | 2.4" | 🚿 Regular watering |
| Jun | 4.3" | 0.9" | 3.4" | 🚿 Regular watering |
| Jul | 4.3" | 1.2" | 3.1" | 🚿 Regular watering |
| Aug | 4.3" | 1.5" | 2.8" | 🚿 Regular watering |
| Sep | 4.3" | 1.3" | 3" | 🚿 Regular watering |
| Oct | — | 1.2" | 0" | ❄️ Dormant |
| Nov | — | 0.9" | 0" | ❄️ Dormant |
| Dec | — | 0.9" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Sep in Shoshone 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 — Shoshone County, ID
Rhubarb Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | May 31 | May 31 – Jun 14 |
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 · 2-3 times/week
📅 Days to Maturity
365–730 days
🧪 Soil pH
Needs 6–7 · Your soil: too_alkaline
🗺️ USDA Zone
Zone 5a
📆 Growing Season
139 days in Shoshone County
Growing Tips for Rhubarb in Shoshone County
Direct sow Rhubarb outdoors after May 10 in Shoshone County when soil has warmed and frost danger has passed.
Your 139.0-day growing season in Shoshone County is tight for Rhubarb (365.0-730.0 days to maturity). Start indoors and choose early-maturing varieties.
Shoshone County receives only 14" 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 Shoshone County, ID?
Shoshone County is in Zone 5a with an average last frost of May 10. Plan your Rhubarb planting based on this frost date — see the calendar above for exact timing.
What planting zone is Shoshone County, ID?
Shoshone County, Idaho is in USDA Hardiness Zone 5a. The average last spring frost is May 10 and first fall frost is September 26.
Plan Your Garden with Confidence
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