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.
August has seemed dull and bleak with flooding, storms and grey skies. The rain has brought benefits to plants leaving grass green, shrubs and trees verdant and gardens needing little watering. Flowers and more delicate plants can be damaged by heavy rain and stormy weather but gardens seem to have held up well. The hedges are now filled with fruits; haws, sloes, rosehips and blackberries, rich food for birds and mammals, before the cold weather draws in.
In the garden
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); 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.
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.
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
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
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.
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.
Make semi ripe cuttings
Cuttings taken after the stems have started to ripen and harden are called semi ripe cuttings. These are often easier to root as the stems are less likely to wilt. Many shrubs and woody perennials can be propagated this way. Plants include Buxus, Choisya, Cistus, Escallonia, Fuchsia, Hydrangea, Lavandula, penstemon, Salvia and Weigela.
Choose a fresh stem from the current seasons growth with a hard base and a soft tip. Cut out the soft leading tip and then a 5-15cm shoot below this point, remove the lower leaves leaving one or two pairs at the top and partially cut away any large leaves to reduce water loss. Cut into the hard part of the stem and remove a sliver of bark at the base to increase the likelihood of rooting. Plant the stems in a mix of 50.50 peat free compost and grit. Keep moist but not too wet. Place in a warm, light position but not in direct sunlight. Cover the pot with a plastic bag to keep damp. Roots will develop over the next few months producing small, new plants.
Store apples and pears
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.
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.
Rethink your growing space
Now is a good time to take stock of your growing space. Take notes and photos, make sketches, think about what worked and any problems or gaps. Are there any dead spaces? Is there enough colour and texture in the space? Do particular times of year lack interest? You can get inspiration for improvements or experiments next year from gardening books and magazines, or visiting local gardens open under the NGS and local community gardens, both often sell plants cheaply too.
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
- Relocate evergreen shrubs.
- Begin to plant smaller shrubs particularly towards the end of September when the weather is conducive to new root growth and establishment.
- Give hedges a final trim before winter.
- Collect tree and shrub seeds for sowing.
- 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.
- Plant out or transplant biennials.
- Sow seeds of perennials and hardy annuals such as calendula, cerinthse, scabiosa, cornflowers and ammi to flower next summer.
- Plant up autumn flowering containers using plants such as sedums, heathers, heucheras, cyclamen, skimmias and pansies.
- Fill gaps with late flowering perennials to provide nectar for pollinators.
- Divide and replant congested herbaceous perennials.
- Prune lavender stems after flowering.
- Deadhead dahlias.
- 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 before they are blown down.
- Store undamaged fruits, preserve any blemished fruits after removing damaged parts in jars, as jams and jellies, by drying or in the freezer.
- Prune back to the ground the spent stems of blackberries when the fruits have been harvested.
- Prune back last years canes of summer fruiting raspberries to the ground and tie in the fresh stems.
- 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.
- Leave sunflower heads for birds to feed on.
- 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.
- Wash and disinfect bird feeders.
- Leave fallen fruit, sticky plums and over ripe bananas on a feeding table to attract butterflies.
- Sow a wildflower patch for flowering next spring and summer.
- 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.
- Scarify and aerate lawns then apply an autumn feed high in potassium.
- Renovate or plant a lawn from seed.
- Repair patchy turf.
- Take notes of gaps in your planting and areas that have worked or been problematic to prepare for rethinking in the following growing year.
- Clear water butts and check fittings in preparation for autumn rains.
- Begin to collect fallen leaves to turn into leaf mould.
A biography of the plants and creatures that inhab a meadow over a period of year.
The Holistic Orchard: Tree Fruits and Berries the Biological Way
How to manage an orchard holistically including orchard design, soil biology, organic treatments and a healthy orchard ecosystem.
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Things to see, places to go
RHS Chelsea Flower Show
Held for the first time ever in September, booking essential.
Tues 21st Sept-Sun 26th Sept
Royal Hospital Chelsea, Royal Hospital Road, London SW11 4BY
Brixton Orchard Volunteer Sessions
Free sessions by Urban Growth Learning Gardens.
Thursday in September: 9th/13th/23rd/30th from 13.00-14.30
Brixton Hill, London SW2 1EG