Season Fit Worksheet
Two dates from your extension service, one number from the packet. Everything else follows.
BFCBrilliance · bfcbrilliance.com/tools/frost-date-planting-calculator
The arithmetic
- Frost-free days
- last spring frost → first autumn frost
- Days needed
- maturity + picking window + buffer
- Slack
- frost-free days − days needed
- Slack is ALSO
- latest sowing, days after spring frost
- Longest variety that fits
- season − window − buffer
- Successions
- slack ÷ gap, + 1
- ⚠ Negative slack
- it does not fit — change something
- ⚠ Days to maturity
- from SOWING or PLANTING OUT?
- ⚠ Both frost dates
- probabilities, not promises
This crop
- Crop and variety
- My last spring frost
- My first autumn frost
- FROST-FREE DAYS
- Days to maturity
- Counts from (sow / plant out)
- Picking window
- Buffer
- DAYS NEEDED
- SLACK
- SUCCESSIONS
- Longest variety that fits
Crops against your season
| Crop | Maturity | Needs | Slack | Fits? |
|---|---|---|---|---|
Before you order seed
- Both frost dates from a local source, not a national average
- Days to maturity checked: from sowing or from planting out?
- Picking window included, not just first harvest
- Buffer set deliberately rather than left at zero
- Longest-variety figure taken to the catalogue if it does not fit
- Later successions expected to run slower than the packet says
- Season extension considered - cloche, tunnel, fleece, warm wall
- Day length considered for crops that care about it
- Actual dates recorded this year for next year's planning
Maturity is the first harvest, not the last
A crop that matures exactly at the first frost gives you one picking, not a season of them. If you intend to harvest over three weeks, those weeks belong inside the season alongside the growing time - which is why the picking window is a separate field rather than something folded into maturity.
If it does not fit, buy a shorter variety
The longest-maturing-variety figure turns a negative slack into a concrete shopping instruction: filter the catalogue below that number. The other three options are starting indoors, extending the season with cover, and growing something else - all real, all better than sowing something that runs out of season in October.