When to plant onion in Dallas
Onion is cold-hardy, so every date keys off Dallas's frost dates of Mar 3.
Step 1 · Sow
Start seeds indoors
Dec 23 – Jan 13
Before your last frost, on a warm windowsill or heat mat.
Step 2 · Plant
Transplant outdoors
Dec 25 – Jan 15
Once frost risk has passed and nights stay mild.
Step 3 · Harvest
Harvest window
Mar 25 – Apr 14
Picking runs until conditions turn against the crop.
Window
Days to maturity
90 – 110 d
Dallas's 276-day season leaves this much room.
Onion on Dallas'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
MAR 3
NOV 28
Common questions
When will onion be ready to harvest in Dallas?
Expect to harvest from around late March (Mar 25–Apr 14) in Dallas, based on its local frost dates. Confidence 80%.
When should I start onion seeds indoors in Dallas?
Start seeds indoors around late December (Dec 23–Jan 13) in Dallas, based on its local frost dates. Confidence 85%.
When can I transplant onion outdoors in Dallas?
Transplant outdoors around late December (Dec 25–Jan 15) in Dallas, based on its local frost dates. Confidence 86%.
How long is the growing season in Dallas?
Dallas has roughly 276 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 Dallas's frost dates.
Confidence 89/100 · Curated · based on NOAA GHCN-Daily 1991–2020 normal · frost dates are probabilities, not guarantees.