September in the Garden
September brings a clear change of pace. Days are shorter, mornings can be dewy and cooler, yet there is often enough warmth for a productive final flush. Maincrop potatoes, apples, pears, beans and tomatoes need regular attention, while squashes must be gathered before cold, wet weather arrives. Empty spaces now offer an opportunity to sow cover crops, plant bulbs and put the plot into good order for autumn.
What to sow & plant in September
Sow hardy winter salads, spinach, land cress, rocket and mustard greens under cover or beneath cloches for late leaves. Sow green manures, such as field beans, grazing rye or winter tares, on cleared ground to protect and improve soil. Plant spring-flowering bulbs in borders, pots and naturalised grass, except tulips which can wait until November. Plant out spring cabbage and overwintering onions where suitable. Later in the month, plant garlic in a sunny, free-draining bed if local conditions are not too wet.
Garden jobs for September
Harvest maincrop potatoes on a dry day and store only sound, dry tubers somewhere cool, dark and frost-free. Cut squashes with a short stem and cure them in a warm, airy place before storage. Gather apples and pears carefully as they ripen, handling them gently. Remove spent vegetable plants, but leave healthy roots in the soil where practical. Tie in autumn-fruiting raspberries, divide overcrowded perennials and continue deadheading. Rake up diseased leaves separately from healthy compost material, and clean greenhouse glass to maximise autumn light.
Northern England & Scotland
In northern England and Scotland, first cool nights can arrive early, so gather squashes, outdoor tomatoes and beans before growth stalls. Choose quick green manures and protect salad seedlings beneath fleece or in a greenhouse. Garlic is often best planted in a raised, free-draining bed to avoid winter waterlogging. Lift maincrop potatoes promptly if wet weather becomes persistent, and store them frost-free.
Southern England
Milder southern gardens often retain useful warmth through September, allowing another worthwhile sowing of spinach, rocket and radish outdoors. Tomatoes, peppers and courgettes may continue well, but remove shading and improve ventilation as light levels fall. Spring bulbs can go into warm, workable soil early in the month. Delay garlic planting if conditions remain very dry, watering the bed first if needed.
Gardening in September: frequently asked questions
What can I sow or plant in September in the UK?
Sow hardy winter salads, spinach, land cress, rocket and mustard greens under cover or beneath cloches for late leaves.
What garden jobs are there in September?
Harvest maincrop potatoes on a dry day and store only sound, dry tubers somewhere cool, dark and frost-free.
What is different in northern Britain in September?
In northern England and Scotland, first cool nights can arrive early, so gather squashes, outdoor tomatoes and beans before growth stalls.
Timing varies with the season and your local conditions; the RHS or a local garden centre can advise. Page updated 19 Sep 2026.