When to plant spinach in Boise
Spinach is cold-hardy, so every date keys off Boise's frost dates of May 2.
Step 1 · Sow
Direct sow outdoors
Mar 21 – Apr 11
Sow straight into warm, workable soil.
Step 2 · Harvest
Harvest window
Apr 30 – May 10
Picking runs until conditions turn against the crop.
Step 3 · Second sowing
Autumn / second sowing
Aug 7 – Aug 21
A second window for a fall crop, timed to mature before the first frost.
Step 4 · Second harvest
Autumn crop harvest
Sep 23 – Oct 3
Maturity window for the second sowing.
Window
Days to maturity
40 – 50 d
Boise's 168-day season leaves this much room.
Spinach on Boise'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
MAY 2
OCT 17
Common questions
When can I sow spinach outdoors in Boise?
Direct-sow around late March (Mar 21–Apr 11) in Boise, based on its local frost dates. Confidence 89%.
When will spinach be ready to harvest in Boise?
Expect to harvest from around late April (Apr 30–May 10) in Boise, based on its local frost dates. Confidence 80%.
Can I plant spinach in autumn in Boise?
Yes — Boise supports a second, autumn sowing of spinach around early August (Aug 7–Aug 21), timed to mature before the first fall frost.
How long is the growing season in Boise?
Boise has roughly 168 frost-free days, which is enough time to grow spinach to maturity outdoors.
The rule of thumb
Sow spinach 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 Boise's frost dates.
Confidence 89/100 · Curated · based on NOAA GHCN-Daily 1991–2020 normal · frost dates are probabilities, not guarantees.