September In The Garden

Peacock butterfly

Peacock butterfly, Charles J Sharp, CC BY-SA

The extreme heat of late August will have stressed many garden plants. Learning to recognise the signs of stress such as wilting, pale foliage, patches of brown and yellow or dropped flowers and leaves will help you manage and revive plants in the aftermath a heat wave. Most plants will need a long and deep watering to soak the soil to a reasonable depth. Watering in the early morning or late evening is the best time for plants to absorb water and to help them recover from a period of drought.

As summer makes way for autumn, days shorten and temperatures are cooler. Colours in the garden are fading, while seeds and fruits ripen. With cooler temperatures, wildlife begins to prepare for winter, fattening up off autumn’s bounty and seeking safe places to roost and shelter at night. Resident birds are quieter now, no longer needing to defend territory and many visiting birds, such as swallows, have begun to migrate south. Peacock and small tortoiseshell butterflies can be seen feeding on nectar while they prepare for winter hibernation in sheds, crevices or tree holes.

In the garden

Tulbaghia violacea 'Variegata'

Tulbaghia violacea ‘Variegata’, Wouter Hagens, CC BY-SA

While September hues are more muted there is still plenty of colour to be found. Gardens with late summer and autumn flowering plants can still look vibrant. Flowers in bloom include the bright yellow daisy heads of the black eyed Susan (Rudbekia); society garlic (Tulbaghia violacea) with delicate clusters of lilac flowers dancing on tall, clump forming stems; the flat headed flowers of the iceplant (Hytophelium sp., formerly known as Sedum spectible); the star burst thistle flowers of sea holly (Eryngium sp.); the yellow plumes of native species golden rod (Soldagio); the blousy, soft pinks or whites of Japanese anemones (such as Anemone ‘Dreaming Swan’ or Anemone x hybrida ‘September Charm’); Asters (Aster frikartii and Aster novi-belgii) with their brightly coloured, daisy like flowers, loved by bees and of course the many brilliant Dahlias.

Carniolan honey bee on goldenrod

Carniolan honey bee on goldenrod, No machine-readable source provided, MikePhobos assumed (based on copyright claims), CC BY-SA

All of these plants provide a late season boost of nectar for insects. If you look closely at these autumn flowering plants you will see they are likely to be crawling with bees and butterflies. Overwintering butterflies, such as the small tortoiseshells, need to take on large quantities of nectar to survive hibernation. Many of the late flowering plants, such as the goldenrod and sea holly, will also have attractive seed heads that can last well into winter and provide seeds and shelter for insects and birds.

Sea buckthorn (Hippophae rhamnoides)

Sea buckthorn (Hippophae rhamnoides), Alan Murray-Rust, CC BY-SA

Bright berries are appearing on many earlier flowering shrubs such as the firethorns (Pyracanthus), Cotoneaster, Viburnum sp and sea buckthorn (Hippophae rhamnoides) and many roses have formed colourful hips. As well as adding colour and form to an early autumn garden, these berries provide food for a wide range of birds, mammals and other creatures.

Traditionally gardens were tidied in autumn but this reduces forage and shelter for wildlife. Structural standing seed heads look beautiful covered in frost and will provide food for wildlife throughout the winter. Piles of logs, twigs, fallen leaves and hollow stems provide habitat and shelter for ladybirds, amphibians and other creatures.

Plant spring flowering bulbs

Wild daffodil (narcissus)

Wild daffodil (narcissus), Martin Hirtreiter, CC BY-SA

It’s time to plant spring flowering bulbs. Daffodils, crocus, hyacinth and allium should be planted in early – mid autumn to enable them to establish and build energy to flower next season. As a general rule plant bulbs to a depth of about 3 times their diameter with a handful of organic compost added to the planting pit to encourage healthy root growth and sand or grit at the base to prevent rotting. Planting in informal groups of 3, 5, or 7 gives a more naturalistic effect. In larger areas, such as lawns, throw handfuls gently and plant them where they land. If planting daffodils, crocus or other bulbs in grass consider that the foliage should not be cut back for 6 weeks after flowering so the area planted will not be able to be mown during this time. Crocus, allium, snake’s head frittilary and grape hyacinth are particularly good for wildlife, providing early nectar for pollinators.

Cover ponds with a net to catch falling leaves

For those lucky enough to have a pond, it is a good time to place a net over the top of it to collect fallen leaves from any surrounding deciduous foliage before the autumn leaf fall starts in earnest. Fallen leaves will eventually turn to silt in the pond, increasing nitrates in the water and risking clouding the pond the following year. It is better to prevent this happening than having to clear the pond of rotting leaves. Use rocks, sticks or pins to hold a reasonable finely meshed net in place taking care not to damage healthy aquatic foliage or tie it higher up between surrounding tougher trunks or stems or well secured canes.

Plant out biennials and perennials

Wallflowers (Erysimum sp)

Wallflowers (Erysimum sp), Mike Pennington, CC BY-SA

Plant out any biennial plants sown earlier in the year and they will have a head start on those planted in the spring. If you didn’t have time to self sow then it should still be possible to buy plants now. These includes foxgloves (Digitalis sp), wallflowers (Erysimum sp), and violets (Viola sp).

September is also good time to plant new perennial plants as the soil is still warm and there is generally more rainfall for them to root in a little before their winter dormancy. Be aware of the eventual height and spread when deciding on an appropriate spot to put them. Be sure to water the plants in well and keep a weather eye out for the possibility of a drier autumn spell in case they need continued irrigation.

Divide perennials

Lifting and dividing congested and spreading clump forming perennials when they are not in active growth will reinvigorate them, keep their spread in check and provide new plants to use or give away. First lift the clump out of the bed by teasing all the way around its base using a hand or garden fork whilst applying gentle upwards force to encourage it to lift away from the soil. Shake off excess soil from the roots back into the planting pit. Separate the plant by hand into distinct smaller plants, either tease smaller distinct plantlets away from the clump or pull more firmly on stronger more fibrous rooted clumps. On larger, heavier clumps, use two forks back to back to form a dividing lever to pull apart larger, firmer clumps or use a sharp knife to divide dense and woody clumps. Aim for good sized new clumps with at least 3-5 healthy shoots. Trim off dead or damaged foliage or roots with a sharp clean knife or secateurs and replant the required new clumps in their chosen space or pot up for later use. Add organic matter to the soil, firm the plants in and water well.

Store apples and pears

Worcester black pear

Worcester black pear, Bob Embleton, CC BY-SA

Apples and pears can be stored in some cases for many months. The fruit that ripens later in the season keeps better than earlier varieties. They prefer a cool, dark, slightly moist environment such as a shaded shed or outhouse. Choose firm, unblemished specimens for storage and keep each fruit separate. They can be stored in boxes or shelves wrapped in greaseproof paper, newspaper or in the formed trays you might find at a greengrocers. Windfalls and earlier fruiting varieties that do not store well can be used for chutneys, jams and juicing.

Collect seeds

Keep collecting seeds for sharing, storing or for planting next season. Try to leave some seed heads on the plants too – they can look very attractive going into winter and provide valuable food for birds and shelter for insects. Store seeds in a cool, dry and dark place. Label the containers with the plant name and date of collection.

Make a habitat box or shelter for hibernating insects

There are many different types of insect hibernation boxes or shelters, many are easy to build, take up very little space and can help beneficial creatures survive the winter. Ladybirds shelter in dead wood, drilling holes in a log and leaving it in a warm dry place, with a roof or cover to keep it dry will create a space for them to overwinter and be ready to tackle aphids in the spring. Twigs and hollow stems, set in a small, simple timber box and hung on a wall or fence may help lacewings that like ladybirds eat aphids. Designs and instructions for making bug boxes, large and small, can be found online.

Gardening tasks in September

Woody Plants

  • Relocate evergreen shrubs.
  • Give hedges a final trim before winter.


  • Continue to deadhead to promote a last flush of flowers.
  • Plant spring flowering bulbs. As a general rule plant bulbs to a depth of about 3 times their diameter with a handful of organic compost in the planting pit to encourage a healthy root growth and sand or grit at the base to prevent rotting. It may help to use a bulb planter for larger bulbs.
  • Collect seeds for next season. Store seeds in a cool, dry and dark place. Label the containers with the plant name and date of collection.
  • Plant new perennial plants. Be aware of their eventual height and spread when deciding on an appropriate spot to put them.
  • Divide and replant congested herbaceous perennials.


  • Cut off and plant out strawberry runners.
  • Think about ordering new bushes and trees for winter planting.
  • Harvest strawberries, autumn raspberries, blackberries, plums, peaches and nectarines, apricots, figs, apples and pears.
  • Prune back to the ground the spent stems of blackberries when the fruits have been harvested.
  • Tie in the new shoots of blackberries that will provide next year’s crop.
  • Prune out the mildewed foliage of apples, pears and gooseberries.


  • Have a gentle tidy. Remove and destroy diseased foliage and clear fallen leaves if they are in access areas and risk becoming slippery. However leave areas of potential shelter in less disturbed areas as well as healthy stems and attractive seed heads that will provide winter forage for birds and mammals and shelter for insects.
  • If planning a bonfire, dismantle the pile and rebuild it in another place before lighting to avoid harming toads, frogs or hedgehogs which may have taken up residence.

Sustainable Practices

  • Cover ponds with a net before the autumn leaf fall starts in earnest. Use rocks, sticks or pins to hold a reasonable finely meshed net in place taking care not to damage healthy aquatic foliage or tie it higher up between surrounding tougher trunks or stems or well secured canes.
  • Renovate or plant a lawn from seed.
  • Take notes of gaps in your planting and areas that have worked or been problematic to prepare for rethinking in the following growing year.

Relaxing reading

The Garden Jungle

Dave Goulson

Learn how to garden to encourage biodiversity and discover the creatures that live in our parks and gardens, pavement cracks and in the soil beneath us.

Buy >

How to Grow Stuff

Alice Vincent

This books gives you the basic knowledge needed to grow plants inside and out in the smallest of spaces.

Buy >

We are a participant in the Amazon EU Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Our recommendations are independent and are in no way influenced by any advertiser or commercial initiative, but we may earn a small commission if a reader clicks through and makes a purchase. By clicking on an affiliate link, you accept that third-party cookies will be set.

Things to see, places to go

Magic Mushroom Mondays (Fungi Identification)

Get started exploring the diversity of fungi to be found in South London's woods and commons this Autumn at these weekly identification sessions. Beginners and experts alike are welcome to bring their finds and share their knowledge.


2nd September 2019, 5pm - 8pm; then every Monday until 25 November 2019


South London Botanical Institute, 323 Norwood Road, London SE24 9AQ

Learn more >

Save, Share, Love: Seed Saving for Beginners

Learn the basics of saving your own seed from common vegetables, herbs and flowers to become more self-sufficient, to save money and to grow healthier, more vigorous crops which are adapted to your local environment.


19 September 2019, 6pm - 8.30pm


Rainbow Grow, Hackney CVS / The Adiaha Antigha Centre, 24-30 Dalston Lane, London E8 3AZ

Learn more >

Catriona Andrews


Catriona is a landscape designer and environmental educator. Her work combines naturalistic planting and sustainable practices to create spaces that are sensitive to the environment and welcoming to wildlife. She designs private gardens, community gardens and public spaces and leads courses and workshops on garden and planting design and the environment.