GardenCalc
Updated August 2026. Reference point: postcode district G1, Glasgow city centre reference point. Your own postcode may differ by a week or two, so check your exact frost dates.
Glasgow frost dates at a glance
Sowing and planting-out windows for Glasgow, 2026
Every date below is worked out from Glasgow's safe last-frost date (6 May) using RHS and Thompson & Morgan sowing offsets. Windows are for outdoor-grown plants; greenhouse crops start earlier.
| Crop | Sow indoors | Sow direct outside | Plant out |
|---|---|---|---|
| Tomatoes tender | 11 Mar to 25 Mar | – | 6 May to 20 May |
| Potatoes tender | – | 18 Mar to 22 Apr | 18 Mar to 22 Apr |
| Runner beans tender | 25 Mar to 15 Apr | 6 May to 17 Jun | 6 May to 20 May |
| Sweet peas hardy | 1 Feb to 25 Mar (held to February, the earliest in the cited guidance) | 25 Mar to 6 May | 25 Mar to 6 May |
| Dahlias tender | 11 Feb to 25 Mar | 8 Apr to 22 Apr | 6 May to 20 May |
| Courgettes tender | 25 Mar to 15 Apr | 6 May to 3 Jun | 13 May to 27 May |
| Cucumbers (outdoor) tender | 1 Apr to 15 Apr | 13 May to 3 Jun | 13 May to 27 May |
| Sunflowers half-hardy | 11 Mar to 8 Apr | 8 Apr to 20 May | 6 May to 20 May |
| Pumpkins and winter squash tender | 25 Mar to 15 Apr | 6 May to 3 Jun | 6 May to 27 May |
| Sweetcorn tender | 25 Mar to 8 Apr | 6 May to 27 May | 6 May to 27 May |
| French beans tender | 1 Apr to 22 Apr | 6 May to 24 Jun | 6 May to 20 May |
| Chillies tender | 1 Feb to 11 Mar (held to February, the earliest in the cited guidance) | – | 13 May to 3 Jun |
| Sweet peppers tender | 25 Feb to 18 Mar | – | 13 May to 3 Jun |
| Basil tender | 11 Mar to 22 Apr | 20 May to 17 Jun | 13 May to 3 Jun |
| Geraniums and tender bedding half-hardy | – | – | 6 May to 20 May |
Get windows for your own postcode → Full UK planting calendar →
Before the first frost in Glasgow (typically 10 Nov)
- Tomatoes: Pick all remaining fruit before the first frost and ripen it indoors, or lift whole plants and hang them under cover. Source
- Potatoes: Lift maincrop potatoes on a dry day before the first hard frost; frosted tubers rot in store. Source
- Runner beans: Pick the last pods before the first frost, then cut plants down to the base and leave the nitrogen-rich roots in the soil. Source
- Sweet peas: Hardy, so no rescue needed; pull up finished plants in autumn, and overwinter any autumn-sown seedlings in a cold frame. Source
- Dahlias: The first frost blackens the foliage; cut stems down, then lift and store the tubers somewhere frost free, or mulch deeply and leave them in the ground in mild areas. Source
- Courgettes: Pick all remaining fruit before the first frost, which kills the plants outright. Source
- Cucumbers (outdoor): Harvest the remaining fruit before the first frost; outdoor plants collapse in the first freeze. Source
- Sunflowers: Plants die back with the first frosts; leave the seedheads standing for the birds, or cut and dry them first if you want the seed. Source
- Pumpkins and winter squash: Harvest and cure the fruits before the first frost; frosted pumpkins cannot be stored. Source
- Sweetcorn: Pick any remaining cobs before the first frost, which ends the crop. Source
- French beans: Pick the last beans before the first frost; even a light frost kills the plants. Source
- Chillies: Bring plants under cover, or pick every remaining fruit, before the first frost; chillies will not survive it outside. Source
- Sweet peppers: Pick the remaining fruit, and fleece outdoor plants or bring potted ones under cover, before the first frost. Source
- Basil: Bring pots indoors or pick the remaining leaves before the first frost; one cold night finishes basil outdoors. Source
- Geraniums and tender bedding: Bring containers under cover, and lift and pot up bedded plants, before the first frost; or take cuttings in late summer and treat the parents as annuals. Source
Is there a frost risk tonight? Live forecast → Farm shops near Glasgow →
Ground frost days by month, Glasgow
Average number of days with a ground frost each month, 1991 to 2020 (observed, Met Office).
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 17 | 15 | 14 | 9 | 3 | 0 | 0 | 0 | 1 | 6 | 12 | 18 |
Glasgow frost and sowing questions
When is the last frost in Glasgow?
In Glasgow the last air frost is typically around 9 Apr, and it is safe (9 years in 10) from about 6 May. The latest recorded in the 30-year record was 12 May. Based on Met Office HadUK-Grid 5 km data, 1991 to 2020, for postcode district G1.
When is the first frost in Glasgow?
The first autumn air frost in Glasgow typically arrives around 10 Nov. It has come as early as 16 Oct in the 30-year record.
How many frost-free days does Glasgow get?
About 215 frost-free days a year, between the typical last spring frost and the typical first autumn frost.
When can I plant out tomatoes in Glasgow?
After the safe last-frost date, so from about 6 May in Glasgow, and within the first two weeks after it. Sow them indoors 6 to 8 weeks before that.
Where these dates come from
Frost dates: Met Office HadUK-Grid 5 km gridded daily minimum temperature, 1991 to 2020, air frost at 0°C, for postcode district G1 (Contains public sector information licensed under the Open Government Licence v3.0). "Safe" means 9 years in 10 the last frost had already passed by that date. Limits: a 5 km grid smooths frost hollows, valley bottoms and urban heat islands, so a sheltered city garden or an exposed edge-of-town plot can differ. Sowing offsets: RHS and Thompson & Morgan grow guides, linked per crop above. This page is not a forecast; use the live forecast for tonight.
Frost warnings and sowing reminders for Glasgow
Join the GardenCalc newsletter. Three short emails a week (Mondays, Thursdays and Fridays), plain talk on what to sow now, and a heads-up when frost is coming.
No spam. Unsubscribe anytime. We respect your inbox.