When to plant onion in Arlington
Onion is cold-hardy, so every date keys off Arlington's frost dates of Apr 8.
Step 1 · Sow
Start seeds indoors
Jan 28 – Feb 18
Before your last frost, on a warm windowsill or heat mat.
Step 2 · Plant
Transplant outdoors
Apr 9 – Apr 30
Once frost risk has passed and nights stay mild.
Step 3 · Harvest
Harvest window
Jul 8 – Jul 28
Picking runs until conditions turn against the crop.
Window
Days to maturity
90 – 110 d
Arlington's 206-day season leaves this much room.
Onion on Arlington'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
APR 8
NOV 3
Common questions
When will onion be ready to harvest in Arlington?
Expect to harvest from around early July (Jul 8–Jul 28) in Arlington, based on its local frost dates. Confidence 79%.
When should I start onion seeds indoors in Arlington?
Start seeds indoors around late January (Jan 28–Feb 18) in Arlington, based on its local frost dates. Confidence 84%.
When can I transplant onion outdoors in Arlington?
Transplant outdoors around early April (Apr 9–Apr 30) in Arlington, based on its local frost dates. Confidence 85%.
How long is the growing season in Arlington?
Arlington has roughly 206 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 Arlington's frost dates.
Confidence 88/100 · Curated · based on NOAA GHCN-Daily 1991–2020 normal · frost dates are probabilities, not guarantees.