September Gardening Jobs: Your Early‑Autumn Checklist

As summer begins to soften into early autumn, September offers the perfect moment to prepare your garden for the cooler months ahead. The soil remains warm, moisture levels rise, and conditions are ideal for planting, pruning, and refreshing tired borders. With a little attention now, your garden will stay vibrant well into autumn — and be well‑prepared for spring.

Sowing & Planting:

- Spring bulbs

Daffodils, snowdrops and tulips create beautiful spring displays in borders and containers. Most spring‑flowering bulbs should be planted by the end of September, with the exception of tulips, which are best planted in November to reduce the risk of disease. Look out for new varieties alongside classic favourites.

For containers, plant two staggered layers of daffodil bulbs to achieve a fuller, more dramatic display. Plant deeply enough to allow winter and spring bedding — such as pansies, primroses, violas and wallflowers — to be added on top.

- Sweet peas

Autumn sowing often produces stronger sweet pea plants. Avoid soaking seeds, as they may rot. Use a good seed and potting compost and sow into root trainers, sweet pea tubes, pots or trays. Cover with glass or place in a propagator at around 15°C (59°F). Once seedlings emerge, move them to a cold frame and pinch out the tips when they reach 10cm (4in).

- Seasonal bedding

Once summer bedding fades, refresh containers, baskets and gaps in borders with winter pansies, violas, cyclamen, wallflowers and sweet Williams.

- Perennials

Late September is an excellent time to plant new perennials. The soil is still warm, and increasing moisture helps roots establish quickly.

Propagation:

-Collecting seeds

Gather seed heads from annuals and perennials, placing them in paper bags to dry for a few days. Clean and store in labelled envelopes for next year.

- Rose cuttings

Shrub roses and ramblers can be propagated easily now. Take a 30cm (12in) stem, trim just below a leaf joint, remove the soft tip, and strip all but the top two or three leaves. Insert the cutting halfway into a well‑prepared trench and leave for twelve months to root.

Edibles:

- Quick‑maturing salads

In southern England, you can still sow fast crops such as summer lettuce, radish, rocket, sorrel, chicory and fennel. Use a cloche outdoors to speed up germination.

- Autumn and winter crops

Continue sowing spring cabbage, turnips, Oriental vegetables and overwintering onions.

- Green manures

Sow crimson clover or Italian ryegrass to improve soil structure and protect bare ground. When dug in, they conserve nutrients and enrich the soil.

Lawn Care:

As growth slows, mow less frequently and raise the cutting height to help the lawn withstand changing weather.

Apply an autumn lawn fertiliser high in potash and phosphates to strengthen grass against frost. Avoid high‑nitrogen feeds, which encourage soft growth easily damaged by cold.

You can still re‑seed bare patches, and September is an excellent time to prepare ground for sowing a new lawn while the soil remains warm.

Click here to read our Autumn Lawn Care blog.

In the Greenhouse:

Reduce damping down as temperatures fall. Water early in the day so the greenhouse dries before evening — damp, cool nights encourage grey mould (Botrytis) and damping off.

Damping off causes seedlings to collapse under white fungal growth and is particularly common when sowing indoors or under glass, so good ventilation and careful watering are essential.

General Garden Care:

Continue deadheading, watering and feeding containers and hanging baskets.

Keep newly planted areas well watered, using rain or grey water where possible.

Prune climbing roses once they have finished flowering; side shoots from the main branches can be cut back to a couple of buds. Any dead, diseased or spindly growth should be cut out and new young shoots tied in to the supports, from the base. If there is an old, thick and woody, unproductive stem, it can be removed from the base to stimulate more vigorous growth.

Give evergreen hedges a final trim before winter.

Clear fallen leaves promptly to reduce disease risk. Shred them first to speed up composting.

Click here to visit our Garden care page for information.