When to plant onion in Fremont
Onion is cold-hardy, so every date keys off Fremont's frost dates of Feb 25.
Step 1 · Sow
Start seeds indoors
Dec 17 – Jan 7
Before your last frost, on a warm windowsill or heat mat.
Step 2 · Plant
Transplant outdoors
Feb 16 – Mar 9
Once frost risk has passed and nights stay mild.
Step 3 · Harvest
Harvest window
May 17 – Jun 6
Picking runs until conditions turn against the crop.
Window
Days to maturity
90 – 110 d
Fremont's 277-day season leaves this much room.
Onion on Fremont's growing year
Frost-bounded season with crops mapped onto the 12-month axis.
Frost risk Growing Harvest
JAN
FEB
MAR
APR
MAY
JUN
JUL
AUG
SEP
OCT
NOV
DEC
FROST
FROST
FEB 25
NOV 29
Common questions
When will onion be ready to harvest in Fremont?
Expect to harvest from around mid May (May 17–Jun 6) in Fremont, based on its local frost dates. Confidence 72%.
When should I start onion seeds indoors in Fremont?
Start seeds indoors around mid December (Dec 17–Jan 7) in Fremont, based on its local frost dates. Confidence 76%.
When can I transplant onion outdoors in Fremont?
Transplant outdoors around mid February (Feb 16–Mar 9) in Fremont, based on its local frost dates. Confidence 78%.
How long is the growing season in Fremont?
Fremont has roughly 277 frost-free days, which is enough time to grow onion to maturity outdoors.
The rule of thumb
Sow onion as soon as the soil is workable — it tolerates cool weather and light frost. Every date on this page is derived from that rule and Fremont's frost dates.
Confidence 80/100 · Curated · based on NOAA GHCN-Daily 1991–2020 normal · frost dates are probabilities, not guarantees.