Cosmos · Phnom Penh, Phnom Penh, Cambodia
When to sow cosmos in Phnom Penh
Main outdoor window
not outdoors here
The window this page is built around.
Timed from last spring frost
no spring frost
In Phnom Penh, 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 Phnom Penh
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.
Cosmos through the year
Against the frost risk in Phnom Penh
Why these dates
Sow direct around the last frost date. Pinch young plants once to produce a bushier, more productive plant.
Frost-tender at both ends, but flowers freely until the first autumn frost stops it outright.
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. Cosmos are timed from 4 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 Phnom Penh.
Also in Phnom Penh
Other flowers to time
Growing cosmos in Phnom Penh
How much frost will cosmos tolerate?
Frost-tender at both ends, but flowers freely until the first autumn frost stops it outright.