Marigold · Karaj, Alborz Province, Iran
When to sow marigolds in Karaj
Main outdoor window
8-22 May
The window this page is built around.
Timed from last spring frost
1 May
In Karaj, on your chosen risk.
Ready to pick
27 Jun - 17 Jul
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 Karaj
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
20 Mar - 3 Apr
Six weeks before your last frost, under cover or on a windowsill.
Sow direct
8-22 May
One week after your last frost.
Plant out
8-22 May
One week after your last frost.
In flower
27 Jun - 17 Jul
Marigolds through the year
Against the frost risk in Karaj
Why these dates
Six weeks indoors produces flowering plants at transplant time. Direct sowing works but flowers three weeks later.
Killed by frost at both ends of the season, with no tolerance at any growth stage.
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. Marigolds are timed from 6 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 Karaj.
The median frost-free season here is 179 days, against 50 to 70 days to first flower for this crop counted from sowing. That margin is what decides whether a late sowing is worth attempting.
Also in Karaj
Other flowers to time
Growing marigolds in Karaj
When should I plant marigolds in Karaj?
Aim for 8-22 May in an average year. If you would rather not gamble on the weather, wait until 24 May - 7 Jun - by then frost has finished in nine years out of ten.
When will marigolds be ready to harvest in Karaj?
Expect to start picking around 27 Jun - 17 Jul, based on 50 to 70 days to maturity from the planting date calculated for this location.
How much frost will marigolds tolerate?
Killed by frost at both ends of the season, with no tolerance at any growth stage.