Marigold · Qingpu, Shanghai, China
When to sow marigolds in Qingpu
Main outdoor window
9-23 Mar
The window this page is built around.
Timed from last spring frost
2 March
In Qingpu, on your chosen risk.
Ready to pick
28 Apr - 18 May
If you plant at the start of the window.
The average last frost. Half of all years are later than this.
Step by step in Qingpu
Each window is a range, not a single day. Earlier in the range buys you a longer season; later in it buys you a safer one.
Start indoors
19 Jan - 2 Feb
Six weeks before your last frost, under cover or on a windowsill.
Sow direct
9-23 Mar
One week after your last frost.
Plant out
9-23 Mar
One week after your last frost.
In flower
28 Apr - 18 May
Marigolds through the year
Against the frost risk in Qingpu
Why these dates
Six weeks indoors produces flowering plants at transplant time. Direct sowing works but flowers three weeks later.
Killed by frost at both ends of the season, with no tolerance at any growth stage.
Seed packets and extension guides express timing as weeks either side of the last spring frost, because that is the only reference point that travels. Marigolds are timed from 6 weeks before that frost for an indoor start, with planting out 1 weeks after it, and this page simply resolves those offsets against the frost date computed for Qingpu.
The median frost-free season here is 287 days, against 50 to 70 days to first flower for this crop counted from sowing. That margin is what decides whether a late sowing is worth attempting.
Also in Qingpu
Other flowers to time
Growing marigolds in Qingpu
When should I plant marigolds in Qingpu?
Aim for 9-23 Mar in an average year. If you would rather not gamble on the weather, wait until 21 Mar - 4 Apr - by then frost has finished in nine years out of ten.
When will marigolds be ready to harvest in Qingpu?
Expect to start picking around 28 Apr - 18 May, based on 50 to 70 days to maturity from the planting date calculated for this location.
How much frost will marigolds tolerate?
Killed by frost at both ends of the season, with no tolerance at any growth stage.