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When to plant swiss chard in Boston

Swiss chard is cold-hardy, so every date keys off Boston's frost dates of Apr 4.
Step 1 · Sow
Start seeds indoors
Mar 7 – Mar 28
Before your last frost, on a warm windowsill or heat mat.
Step 2 · Plant
Transplant outdoors
Apr 7 – Apr 28
Once frost risk has passed and nights stay mild.
Step 3 · Harvest
Harvest window
May 27 – Jun 6
Picking runs until conditions turn against the crop.
Step 4 · Second sowing
Autumn / second sowing
Aug 11 – Aug 25
A second window for a fall crop, timed to mature before the first frost.
Step 5 · Second harvest
Autumn crop harvest
Oct 7 – Oct 17
Maturity window for the second sowing.
Window
Days to maturity
50 – 60 d
Boston's 220-day season leaves this much room.
Swiss chard on Boston'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
APR 4
NOV 9

Common questions

When can I sow swiss chard outdoors in Boston?

Direct-sow around early April (Apr 7–Apr 28) in Boston, based on its local frost dates. Confidence 86%.

When will swiss chard be ready to harvest in Boston?

Expect to harvest from around late May (May 27–Jun 6) in Boston, based on its local frost dates. Confidence 80%.

When should I start swiss chard seeds indoors in Boston?

Start seeds indoors around early March (Mar 7–Mar 28) in Boston, based on its local frost dates. Confidence 85%.

When can I transplant swiss chard outdoors in Boston?

Transplant outdoors around early April (Apr 7–Apr 28) in Boston, based on its local frost dates. Confidence 86%.

Can I plant swiss chard in autumn in Boston?

Yes — Boston supports a second, autumn sowing of swiss chard around mid August (Aug 11–Aug 25), timed to mature before the first fall frost.

How long is the growing season in Boston?

Boston has roughly 220 frost-free days, which is enough time to grow swiss chard to maturity outdoors.

The rule of thumb

Sow swiss chard 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 Boston's frost dates.

Confidence 89/100 · Curated · based on NOAA GHCN-Daily 1991–2020 normal · frost dates are probabilities, not guarantees.
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