Gladiolus · Shanghai, Shanghai, China
When to sow gladioli in Shanghai
Main outdoor window
16 Mar - 13 Apr
The window this page is built around.
Timed from last spring frost
2 March
In Shanghai, on your chosen risk.
Ready to pick
1 Jul - 30 Sep
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 Shanghai
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.
Plant the corms
16 Mar - 13 Apr
After the last frost, once the soil has warmed. This crop is never fully dormant, so it cannot be planted bare-root in winter.
In flower
1 Jul - 30 Sep
Gladioli through the year
Against the frost risk in Shanghai
Why these dates
Plant corms after the last frost once the soil is above 12C, 10cm deep, and keep planting at two-week intervals until midsummer for a succession of spikes. Tall cultivars need staking or a sheltered spot; a spike in full flower is top-heavy and snaps at the base in wind.
Killed by frost at about -2C. The corms will not survive a freezing soil, so below zone 8 lift them once the leaves yellow, dry them for a fortnight and store frost-free.
Gladioli are planted once and then left in place, so there is no sowing offset to resolve. Nor is there a dormant season to plant into: this crop keeps its leaves and keeps growing through the winter, which is exactly why cold damages it. The window on this page therefore waits until the last frost in Shanghai has passed and the soil has begun to warm, giving the roots the longest possible run before the cold returns.
Hardiness is not the obstacle here. Shanghai is zone 9a, comfortably inside the range this crop is rated for, so an established plant should come through an average winter without protection.
Also in Shanghai
Other flowers to time
Growing gladioli in Shanghai
When should I plant gladioli in Shanghai?
Aim for 16 Mar - 13 Apr in an average year. If you would rather not gamble on the weather, wait until 28 Mar - 25 Apr - by then frost has finished in nine years out of ten.
When will gladioli be ready to harvest in Shanghai?
Expect to start picking around 1 Jul - 30 Sep, based on 70 to 100 days to maturity from the planting date calculated for this location.
How much frost will gladioli tolerate?
Killed by frost at about -2C. The corms will not survive a freezing soil, so below zone 8 lift them once the leaves yellow, dry them for a fortnight and store frost-free.