Florence fennel bolts easily in the UK — timing is critical. Here's when to sow, which varieties to choose, and how to avoid the most common failure.
Ready to start growing? Read our full How to Grow Fennel UK →
Sowing dates and growing advice verified against RHS guidance by the SoilCommander Growing Team.
Part of the UK Vegetable Planting Calendar — see all sowing dates and monthly guides.
Florence Fennel Planting Calendar
| Task | Timing | Notes |
|---|---|---|
| Sow Florence indoors (bolt-resistant) | April – May | Individual pots; handle roots gently at transplant |
| Sow Florence outdoors | Late May – June | After last frost; soil 10°C+; south England only |
| Harvest Florence | August – October | When bulb is 8–10cm across; earth up to blanch |
Critical: Always Use Bolt-Resistant Varieties
Standard fennel bolts before forming a bulb in the UK. Always choose Romanesco, Orion F1, or Victorio. Do not sow before mid-April.
Browse all sowing dates in the UK vegetable planting calendar · Explore all UK vegetable growing guides
Plan The Timing Before You Sow
Use the planting window with a planner, seed-starting setup, and the full calendar so dates stay practical for your garden.
Plan the next step
Use the printable UK Vegetable Garden Planner to turn this guide into sowing dates, bed layouts, and weekly garden tasks.