Romanesco · Philadelphia, Pennsylvania, United States
When to plant romanesco in Philadelphia
Main outdoor window
7-28 Apr
The window this page is built around.
Timed from last spring frost
14 April
In Philadelphia, on your chosen risk.
Ready to pick
1 Sep - 30 Nov
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 Philadelphia
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
3-24 Mar
Six weeks before your last frost, under cover or on a windowsill.
Transplant
7-28 Apr
One week before your last frost.
Harvest
1 Sep - 30 Nov
Romanesco through the year
Against the frost risk in Philadelphia
Why these dates
Start indoors six weeks before the last frost and plant out around it, aiming for the head to form in the cooling weather of early autumn rather than in midsummer heat.
Hardy to about -5C. The curd itself is more tender than the leaves and browns after a hard frost, so cut once it is sized rather than leaving it out.
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. Romanesco are timed from 6 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 Philadelphia.
The median frost-free season here is 202 days, against 75 to 100 days to maturity for this crop counted from planting out. That margin is what decides whether a late sowing is worth attempting.
Nearby
Romanesco in places close by
Also in Philadelphia
Other vegetables to time
Growing romanesco in Philadelphia
When should I plant romanesco in Philadelphia?
Aim for 7-28 Apr in an average year. If you would rather not gamble on the weather, wait until 16 Apr - 7 May - by then frost has finished in nine years out of ten.
When will romanesco be ready to harvest in Philadelphia?
Expect to start picking around 1 Sep - 30 Nov, based on 75 to 100 days to maturity from the planting date calculated for this location.
How much frost will romanesco tolerate?
Hardy to about -5C. The curd itself is more tender than the leaves and browns after a hard frost, so cut once it is sized rather than leaving it out.