Seed Starting Calculator
UK Seed Starting Calculator
Planting Timeline
Note: These dates are guidelines based on average frost dates. Always monitor local weather conditions and adjust accordingly.
Perfect Timing for UK Garden Success
Take the guesswork out of seed starting with our UK-specific calculator. Tailored to British growing conditions and regional frost dates, this tool helps you determine the optimal times to start seeds indoors and safely transplant outdoors.UK Regional Frost Dates
| Region | Last Spring Frost | First Autumn Frost |
|---|---|---|
| Southern England | Late March - Early April | Late October - November |
| Midlands | Mid-April | Mid-October |
| Northern England | Late April - Early May | Early October |
| Scotland | Early-Mid May | Late September |
REGIONAL ADVICE
- Coastal areas typically have milder temperatures and later frosts
- Urban areas can be 2-3°C warmer than rural locations
- Highland regions need additional frost protection
- Microclimates in your garden can vary significantly
Popular UK Vegetables - When to Sow
| Vegetable | Indoor Sowing | Outdoor Sowing | Weeks to Germination |
|---|---|---|---|
| Tomatoes | Late February - March | Late May | 7-14 days |
| Broad Beans | February | March - April | 7-14 days |
| Runner Beans | April | May - June | 5-10 days |
| Courgettes | April | Late May | 5-7 days |
| Brussels Sprouts | March | April | 5-10 days |
| Leeks | January - February | March - April | 14-21 days |
WEATHER WATCH TIP
Monitor these conditions before transplanting:- Night temperatures consistently above 8°C
- Soil temperature at least 10°C
- No frost forecast for 2 weeks
- Avoid waterlogged soil conditions
Indoor Starting Requirements
- Maintain temperature between 18-22°C
- Provide 12-16 hours of light daily
- Use proper seed starting compost
- Ensure good air circulation
- Monitor moisture levels carefully
Hardening Off Schedule
| Day | Duration | Conditions |
|---|---|---|
| 1-2 | 1-2 hours | Sheltered spot, mild day |
| 3-4 | 2-4 hours | Partial shelter |
| 5-7 | 4-6 hours | More exposed position |
| 8-10 | 6-8 hours | Full exposure |
| 11-14 | All day & night | Full exposure, protect if frost forecast |
SUCCESSION PLANTING TIP
For continuous harvests throughout the season:- Sow short-season crops every 2-3 weeks
- Plant both early and late varieties
- Use cold frames to extend the season
- Consider polytunnel or greenhouse growing
Protection Methods
- Cloches for individual plants
- Horticultural fleece for rows
- Cold frames for hardening off
- Polytunnels for larger areas
- Wall-side growing for tender plants
AUTUMN SOWING NOTE
For autumn/winter crops, calculate sowing dates backwards from first frost:- Add 2 weeks for hardening off period
- Add growing time to maturity
- Add germination time
- Consider shorter daylight hours