Shiso · Penza, Penza Oblast, Russia
When to plant shiso in Penza
Main outdoor window
9-30 May
The window this page is built around.
Timed from last spring frost
2 May
In Penza, on your chosen risk.
Ready to pick
25 Jul - 14 Aug
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 Penza
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
21 Mar - 11 Apr
Six weeks before your last frost, under cover or on a windowsill.
Sow direct
9-30 May
One week after your last frost.
Plant out
16 May - 6 Jun
Two weeks after your last frost.
Harvest
25 Jul - 14 Aug
Shiso through the year
Against the frost risk in Penza
Why these dates
Killed by the first frost, like basil.
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. Shiso are timed from 6 weeks before that frost for an indoor start, with planting out 2 weeks after it, and this page simply resolves those offsets against the frost date computed for Penza.
The median frost-free season here is 155 days, against 70 to 90 days to maturity for this crop counted from planting out. That margin is what decides whether a late sowing is worth attempting.
Growing shiso in Penza
When should I plant shiso in Penza?
Aim for 9-30 May in an average year. If you would rather not gamble on the weather, wait until 30 May - 20 Jun - by then frost has finished in nine years out of ten.
When will shiso be ready to harvest in Penza?
Expect to start picking around 25 Jul - 14 Aug, based on 70 to 90 days to maturity from the planting date calculated for this location.
How much frost will shiso tolerate?
Killed by the first frost, like basil.