Peak growth, main harvest, and the blight watch.
Scotland’s summer is short but generous: long daylight drives fast growth, and by June frost is behind all but the highest ground. It is the season to plant out the last tender crops, harvest in earnest, and keep succession-sowing for autumn. The catch is the weather: warm, wet, humid spells are the trigger for blight, mildew and grey mould, so airflow and vigilance matter more here than any calendar date.
Month by month
What's in season across summer
Every crop that has a sowing, planting or harvest window in any of these three months, pooled here and detailed by month in the guides above.
🌿 To plant out
Sowing, planting and harvest windows are UK-wide guidance, adjusted only so far as to never open earlier than that guidance states. They are not Scottish-specific dates: much of Scotland runs two to four weeks later than the UK guide, and later still in the north and at altitude. For timing tuned to your own garden, use the region-aware tools below.
Region-aware toolFrost Date CalculatorYour local last and first frost bands: the single most useful number for timing a Scottish season.Watch out for in summer
Vine weevil (adults)
Adults notch leaf edges through summer. The adult stage is recorded as a summer season rather than exact months.
Leek mothRHS UK timing · uncertain in Scotland
Two UK generations: May–June and a more numerous August–October flight. Mesh over alliums is again the practical control.
UK timing, and conditional in the same way as allium leaf miner; presence in Scotland is uncertain and local timing is unverified.
Carrot flyRHS UK timing · uncertain in Scotland
The avoidance model: sowing after mid-May dodges the first generation, and lifting before late August dodges the second. A 60cm fleece/mesh barrier helps whenever carrots are up.
The generation timing is the UK model; the Scottish calendar is not separately sourced. Use it as an avoidance strategy, not a dated forecast.
Mint rustbroad seasonal window
Symptoms can appear from spring until autumn. Cut affected mint to the ground and never propagate from infected plants.
Timing is broad, close to "the whole growing season", so treat it as a standing watch rather than a monthly alert.
Allium leaf minerRHS UK timing · uncertain in Scotland
Two egg-laying periods on alliums: March–April and late summer–autumn. Covering leeks, onions and garlic with fine mesh over those windows is the main defence.
UK timing, and conditional: the pest may not be established across all of Scotland, and where it is, Scottish generations have consistently lagged the UK ones. Treat these as a UK guide, not a Scottish forecast.
These track the weather, not the calendar. Their month-by-month activity isn't sourced, so we tie them to the conditions that trigger them rather than pretend a date:
Grey mould (botrytis)
Watch when: cool, damp, still air, especially under cover
Can occur year-round with latent infections; ventilation and airflow are the real controls. Peaks when growth is soft and air is stagnant.
Slugs & snails
Watch when: mild, wet, damp conditions, worst around soft young growth
Activity tracks moisture and temperature, so risk climbs in any mild damp spell. Pressure is highest on tender seedlings in spring and again in a wet autumn.
Potato & tomato blight
Watch when: warm, humid, muggy spells in the main growing season
June onwards for the UK; Scottish onset not separately sourced, so we tie it to the weather. Watch potatoes and outdoor tomatoes after warm, wet spells.
Powdery mildew
Watch when: dry spells and drought stress at the roots
Driven by dry, warm weather and plants short of water. Keep roots watered and airflow open around courgettes and peas.
Leek rust
Watch when: warm, wet summers with poor airflow
A wet-summer disease that is genuinely more of a Scottish problem than the allium insects. Space alliums generously; driven by leaf wetness, not a date.
Sources
- RHS: grow-your-own guides: sowing, planting and harvest timing for all 25 crops (each window hand-derived from the crop's own RHS prose)
- GrowScotland: pest activity framing: which pests to flag each season is our own reading of RHS activity data. We surface only what RHS sources, and frame weather-driven diseases by trigger conditions rather than inventing a Scottish calendar