Forget-me-not · Putuo, Shanghai, China
When to sow forget-me-nots in Putuo
Main outdoor window
14 Apr - 12 May
The window this page is built around.
Timed from last spring frost
3 March
In Putuo, on your chosen risk.
Ready to pick
1 Apr - 31 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 Putuo
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.
Sow direct
14 Apr - 12 May
Six weeks after your last frost.
Move to final position
21 Jul - 18 Aug
20 weeks after your last frost.
In flower
1 Apr - 31 May
Forget-me-nots through the year
Against the frost risk in Putuo
Why these dates
Sow in early summer, six weeks after the last frost, and move the seedlings in autumn to wherever the spring bulbs are planted. Flowers the following April and May, then pull the plants out as they brown and shake them over the bed to sow next year's crop.
Hardy to about -20C as a rosette. Needs a cold winter, and mildews badly in a humid summer, which is why it is best pulled as soon as flowering finishes.
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. Forget-me-nots are timed with planting out 20 weeks after it, and this page simply resolves those offsets against the frost date computed for Putuo.
Hardiness is not the obstacle here. Putuo is zone 9a, comfortably inside the range this crop is rated for, so an established plant should come through an average winter without protection.
This is a two-season crop, so the dates above describe a sowing in one year and a flowering in the next. The plant spends the winter in the ground as a small rosette, which is why the frost-free season in Putuo does not limit it the way it would limit a tomato: it is not trying to finish before the cold arrives, it is trying to be well enough rooted to sit through it. Sowing too late is the real risk, because a plant that goes into winter undersized often fails to flower at all the following year.
Also in Putuo
Other flowers to time
Growing forget-me-nots in Putuo
When should I plant forget-me-nots in Putuo?
Aim for 14 Apr - 12 May in an average year. If you would rather not gamble on the weather, wait until 25 Apr - 23 May - by then frost has finished in nine years out of ten.
When will forget-me-nots be ready to harvest in Putuo?
Expect to start picking around 1 Apr - 31 May, based on 300 to 335 days to maturity from the planting date calculated for this location.
How much frost will forget-me-nots tolerate?
Hardy to about -20C as a rosette. Needs a cold winter, and mildews badly in a humid summer, which is why it is best pulled as soon as flowering finishes.