Stromboli F1 is your go-to for the earliest calabrese harvests, with tasty, domed heads and plenty of side shoots. It's a vigorous variety that can be autumn-sown for overwintering or spring-sown for a late summer/autumn crop.
Thanks to its resistance to cold-induced growth inhibition, Stromboli can be overwintered with protection. In milder areas, you might be picking as early as January, though most crops are ready from May onward after the slower winter growth.
To grow for an early crop:
Sow in modules from September to early November
Pot on or plant into greenhouse borders or polytunnels, spaced at 50cm apart
Protect from hard frosts with floating fleece
For flexibility, grow in large pots—you can move them outside in spring to free up space indoors
Spring sowings:
Space plants 60–75cm apart—they’ll grow bigger in warmer weather
A note on cold-induced growth inhibition: This isn’t fully understood—cold temperatures are a factor, but low light levels (especially in winter) also play a part. To give your plants the best chance:
Space them out well to maximise available light
Only use fleece when necessary—it reduces light levels
Clean greenhouse glass or polytunnel covers to let in as much light as possible
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