Sweet alyssum · Mexico City, Mexico City, Mexico
When to sow sweet alyssum in Mexico City
Main outdoor window
2 Feb - 2 Mar
The window this page is built around.
Timed from last spring frost
9 February
In Mexico City, on your chosen risk.
Ready to pick
24 Mar - 8 Apr
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 Mexico City
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
15 Dec - 12 Jan
Eight weeks before your last frost, under cover or on a windowsill.
Sow direct
2 Feb - 2 Mar
One week before your last frost.
Plant out
2 Feb - 2 Mar
One week before your last frost.
In flower
24 Mar - 8 Apr
Sweet alyssum through the year
Against the frost risk in Mexico City
Why these dates
Sow direct a week before the last frost, or start indoors eight weeks earlier for immediate effect. Shear the whole plant back by half when it stops flowering in midsummer heat and it will flower again within three weeks. Self-seeds into paving cracks and is welcome there.
Takes light frost to about -6C and often keeps flowering after the first autumn frosts have finished everything around it. In zone 9 and warmer it flowers through winter and behaves as a short-lived perennial.
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. Sweet alyssum are timed from 8 weeks before that frost for an indoor start, with planting out 1 weeks before it, and this page simply resolves those offsets against the frost date computed for Mexico City.
Hardiness is not the obstacle here. Mexico City is zone 9b, comfortably inside the range this crop is rated for, so an established plant should come through an average winter without protection.
The median frost-free season here is 281 days, against 50 to 65 days to first flower for this crop counted from sowing. That margin is what decides whether a late sowing is worth attempting.
Nearby
Sweet alyssum in places close by
Also in Mexico City
Other flowers to time
Growing sweet alyssum in Mexico City
When should I plant sweet alyssum in Mexico City?
Aim for 2 Feb - 2 Mar in an average year. If you would rather not gamble on the weather, wait until 27 Feb - 27 Mar - by then frost has finished in nine years out of ten.
When will sweet alyssum be ready to harvest in Mexico City?
Expect to start picking around 24 Mar - 8 Apr, based on 50 to 65 days to maturity from the planting date calculated for this location.
How much frost will sweet alyssum tolerate?
Takes light frost to about -6C and often keeps flowering after the first autumn frosts have finished everything around it. In zone 9 and warmer it flowers through winter and behaves as a short-lived perennial.