Gardening in Shetland, the Western Isles & Argyll

The islands are maritime through and through. Stornoway's first autumn frost band is early November, later than at the main station of any other region here, and it records about 22 air-frost days a year, against about 43 at Edinburgh's Royal Botanic Garden and 38 at Inverness. Tiree, in the Inner Hebrides, has fewer still at about 9 days a year, with no air frost recorded in May.

The limit is the cool summer, not the winter. July's mean daily maximum is 16.3C at Stornoway and Tiree and 14.4C at Lerwick, against 19.3C at Edinburgh's Royal Botanic Garden, so heat-loving crops need the warmest, most sheltered spot you have. Rainfall is about 1,240 to 1,280mm a year at all three stations, and Tiree is the sunniest of them at about 1,520 hours a year, against about 1,160 at Lerwick.

Lerwick matches Stornoway on the frost bands but has more frost days, about 29 a year, with 2.5 days of air frost in April and 2.2 in November, while Tiree is milder than Stornoway, so read the table as a middle case for the islands. On exposed ground, wind and salt spray are likely to limit growing as much as frost does.

The figures describe low coastal and island ground, so one maritime figure is given rather than a lowland and upland split. None of the stations used sits on the higher ground inland in Argyll, so a glen garden may run later than these dates. Orkney (KW) is covered with the Highlands.

Where this covers

• ZE Shetland
• HS the Western Isles
• KA27 Arran
• PA20-PA78 Argyll and its islands, including Bute, Mull and Islay

Frost dates for Shetland, the Western Isles & Argyll

• Maritime (all populated ground): last frost late April, first autumn frost early November, safe to plant out mid May.

Dates are rounded to the nearest half month, from named Met Office stations (1991-2020 averages). One figure covers the whole area: its stations are all low-lying and close to the sea, which sets the frost pattern here.

Checked against station records at Lerwick and Tiree.

What this means for growing here

Sow and plant out to these dates rather than a UK calendar, and remember they are regional averages. Your own plot can run two to four weeks later in a frost pocket, or earlier against a warm wall. On exposed island sites, shelter from wind and salt usually does more than chasing an early date. The Planting Calendar turns these into a month-by-month plan.

When to plant out tender crops here

Frost-tender crops go outside only once the safe planting-out date has passed, about two weeks after the last frost: mid May across Shetland, the Western Isles & Argyll. That applies to tomatoes, basil, cucumbers, sweetcorn, peppers, chillies and aubergines grown outdoors. That date is the earliest they can go out, not a promise they will ripen: on exposed ground, shelter from wind and salt matters as much as the date.

Articles for gardens in Shetland, the Western Isles & Argyll

• Growing on Machair: What Actually Works on Scotland's Shell-Sand Ground
• Growing Through the Dark: Shetland and Orkney's Six-Hour Winter Days
• Shelter Belt Planting for Exposed Coastal and Island Gardens
• Crofting Law and Growing Rights
• Seaweed Feed: Kelp Meal, Liquid, and What You Can Actually Gather