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Growing Walla Walla in Zone 5b
Allium cepa
✓ Well Suited for Zone 5b
Score: 100/100
🌡️ USDA Hardiness Zone 5b
Moderate Continental
USDA 2023 Verified
Growing Season
140-170 days
Winter Minimum
-15°F to -10°F
(-26.1°C to -23.3°C)
AHS Heat Zone 3-7
8 to 14 heat days per year • Low heat stress
Typical regions: Central US, Mid-Atlantic highlands, Pacific Northwest foothills
📊 Data Source:
USDA Plant Hardiness Zone Map 2023 • Last verified: 1/22/2026
✓ Zone Compatibility Analysis
high confidenceExcellent match: 105 days to maturity with 65 days buffer in 170-day season.
Recommendation: Direct sowing and transplanting both viable. Excellent fit for this zone.
💾 Suitability computed by Solara Agricultural Intelligence Platform
📅 Zone 5b Planting Calendar for Walla Walla
🌱 Start Seeds Indoors
March 12
✓ Database-computed optimal date
🪴 Transplant Outdoors
April 30
✓ Database-computed optimal date
🌾 Direct Sow (Alternative)
2 weeks after last frost
For warm-season crops
🥕 Expected Harvest
August 13
💡 Zone 5b Growing Tips
- • Growing season: 140-170 frost-free days
- • Excellent match for this zone - both direct sowing and transplanting work well
- • Monitor soil temperature before transplanting (minimum 55-60°F for most crops)
⚠️ Zone 5b Challenges
⚠️Variable spring weather
⚠️Occasional late frosts
⚠️Summer drought possible
✅ Best Plants for Zone 5b
✓Full vegetable garden
✓Most fruit trees
✓Wide variety of ornamentals
❄️ Winter in Zone 5b
Moderately cold winters with lows reaching -10°F to -15°F.
☀️ Summer in Zone 5b
Warm to hot summers with extended growing season.
🔥 Heat Management for AHS Zone 3-7
This zone experiences 8 to 14 heat days per year with low heat stress.
🌡️Light mulching
🌡️Adequate watering during heat spells
Source: American Horticultural Society
📊 Walla Walla Quick Facts
Days to Maturity
90-120
Difficulty
intermediate
Season
summer
Type
OP
📍 View Walla Walla Guide for Other Zones
🌱 Other Onion Varieties for Zone 5b
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