When to plant onion in Knoxville
Onion is cold-hardy, so every date keys off Knoxville'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
Mar 29 – Apr 19
Once frost risk has passed and nights stay mild.
Step 3 · Harvest
Harvest window
Jun 27 – Jul 17
Picking runs until conditions turn against the crop.
Window
Days to maturity
90 – 110 d
Knoxville's 201-day season leaves this much room.
Onion on Knoxville'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
OCT 28
Common questions
When will onion be ready to harvest in Knoxville?
Expect to harvest from around late June (Jun 27–Jul 17) in Knoxville, based on its local frost dates. Confidence 80%.
When should I start onion seeds indoors in Knoxville?
Start seeds indoors around late January (Jan 28–Feb 18) in Knoxville, based on its local frost dates. Confidence 85%.
When can I transplant onion outdoors in Knoxville?
Transplant outdoors around late March (Mar 29–Apr 19) in Knoxville, based on its local frost dates. Confidence 86%.
How long is the growing season in Knoxville?
Knoxville has roughly 201 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 Knoxville's frost dates.
Confidence 89/100 · Curated · based on NOAA GHCN-Daily 1991–2020 normal · frost dates are probabilities, not guarantees.