SproutSmart
SproutSmart Intelligent Garden Sowing

White Castle · Onion

Zone 1a Save Garden

Planting Schedule

Add White Castle to your garden to build a schedule and get reminders.
MilestoneDate
Start IndoorsDirect Sow
Last FrostJun 15th
Transplant / Direct Sow OutdoorsJun 8th
Harvest BeginsOct 6th
Harvest EndsJul 15th

Crop Details

Transplant Conditions: Wait until soil reaches 45°F and nights stay above 35°F before moving outdoors. Harden off for 7 days first.
TraitValue
Days to Maturity120
Sun RequirementsFull Sun
Growth HabitBulbing
Support NeededNone
Planting DepthNormal
Germination Temp (°F)65
Min Soil Temp (°F)45
Min Night Temp (°F)35
Harden Off (days)7
Expert Note: For sweet caramelizing onions, keep soil evenly moist and avoid nitrogen-heavy feed once bulbs begin swelling.