Scottish growing tool
Harvest Window Calculator
Every crop has a Sow, Plant and Harvest window, but the standard version is a UK-wide average. This checks it against your region's actual frost dates, so you can see whether that timing genuinely fits where you garden.
Sources
Sow/Plant/Harvest months, per crop:
- Aubergines
- Basil
- Beetroot
- Broad Beans
- Broccoli
- Brussels Sprouts
- Cabbage
- Calabrese
- Carrots
- Cauliflower
- Celeriac
- Celery
- Chard
- Chervil
- Chillies
- Coriander
- Courgettes
- Cucumbers
- Dill
- Endive
- Florence Fennel
- French Beans
- Garlic
- Jerusalem Artichoke
- Kale
- Kohlrabi
- Leeks
- Lettuce
- Onions
- Pak Choi
- Parsley
- Parsnips
- Peas
- Peppers
- Potatoes
- Pumpkins
- Radish
- Rocket
- Runner Beans
- Shallots
- Spinach
- Spring Onions
- Squash
- Swede
- Sweetcorn
- Tomatoes
- Turnip
Frost dates: Met Office location-specific long-term averages and historic station data, 1991-2020 averages, same station data as the Frost Date Calculator.
How it works
Each crop's sow, plant and harvest months come from its RHS growing calendar, which is drawn for the UK as a whole. The calculator sets those months against your region's frost dates, the same Met Office station averages for 1991 to 2020 behind the Frost Date Calculator, split into lowland and upland. For crops that frost kills, it checks two things: whether the RHS planting month comes before it's safe to plant out where you are, and whether the harvest runs on past your first autumn frost.
A worked example
The UK-wide calendar has outdoor tomatoes planted in May or June and picked from July to October. In an upland garden in the north-east, using the Braemar station, it isn't safe to plant out until mid June, and the first autumn frost comes in mid-to-late September. The calculator flags both: plant later than the calendar says, and expect frost to cut the harvest short. In a lowland Edinburgh garden, mid-May planting is fine, but the first frost in late October still lands inside the October harvest, so it warns about that end of the season and suggests lifting the last plants to ripen their fruit under cover.
Reading the result
Frost dates are averages rounded to the half month, and your own plot can run two to four weeks later in a frost pocket, or earlier against a warm wall. Hardy crops don't get these warnings, because frost isn't what limits them.