Calendula · Khulna, Khulna Division, Bangladesh
When to sow calendulas in Khulna
Main outdoor window
not outdoors here
The window this page is built around.
Timed from last spring frost
no spring frost
In Khulna, on your chosen risk.
First autumn frost
no autumn frost
The far end of the outdoor season.
The average last frost. Half of all years are later than this.
Step by step in Khulna
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.
Calendulas through the year
Against the frost risk in Khulna
Why these dates
Sow direct three weeks before the last frost, or start indoors six weeks before it for the earliest flowers. Sow again every three weeks until midsummer for continuous bloom. In mild winters an autumn sowing overwinters as a small rosette and flowers a month earlier than anything sown in spring.
Takes light frost to about -8C without stopping, and often flowers straight through a mild winter in zone 9 and warmer. Heat is the greater enemy: it sulks and mildews above 30C and is best treated as a spring and autumn flower in hot climates.
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. Calendulas are timed from 6 weeks before that frost for an indoor start, with planting out 2 weeks before it, and this page simply resolves those offsets against the frost date computed for Khulna.
Hardiness is not the obstacle here. Khulna is zone 11a, comfortably inside the range this crop is rated for, so an established plant should come through an average winter without protection.
Growing calendulas in Khulna
How much frost will calendulas tolerate?
Takes light frost to about -8C without stopping, and often flowers straight through a mild winter in zone 9 and warmer. Heat is the greater enemy: it sulks and mildews above 30C and is best treated as a spring and autumn flower in hot climates.