Celebrate the Start of Autumn

The days are distinctly shorter and there is a chill in the air that is hard to ignore, but September should be a celebration for the start of Autumn in all of its glory instead of about mourning the end of Summer.

In the garden

Black-eyed Susan, Rudbekia

Black-eyed Susan, Rudbekia, Urszula, CC0

In September, the garden is still full of colour with many late summer and autumn flowering plants performing well. These include the bright yellow daisy flowers of the black eyed Susan, Rudbekia; the rounded clusters of tubular flowers of the African lily, Agapanthus; the flat headed flowers of the iceplant, Hytophelium sp. (formerly known as Sedum spectible); the star burst thistle flowers of sea holly, Eryngium sp. and yellow plumes of native species golden rod, Soldagio.

All of these plants provide a much needed late season boost of nectar for insects. Look closely and the ice plants and black eyed Susan’s, for example, are likely to be crawling with bees and butterflies. Several 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, Manfred Antranias Zimmer, CC0

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

Getting ready for Autumn

As autumn progresses a recurring task will be to keep the garden tidy as the deciduous plants and trees enter their declining phase and die back and loose their foliage. It is good to keep an eye on decaying material as this can harbor pests and disease but a slash and burn approach of cutting back everything and removing all fallen leaves is not necessary. A more relaxed approach to the Autumn clean up is beneficial to wildlife, reduces unnecessary effort and favours the lower back.

Remove and destroy diseased foliage and clear large areas of fallen leaves if they are in access areas and risk becoming slippery mush but aim to leave healthy stems and seedheads on plants and leave a few piles of leaves in less disturbed areas. Perhaps allow hollow stems that are removed from plants to remain on the ground under shrubs or hedges. All of these features will hardly disrupt the overall tidy aspect of a space and provide much needed winter shelter for wildlife such as insects, small mammals and amphibians.

Plant spring flowering bulbs

The spring bulb planting window is officially open. Bulbs such as 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. Do not plant bulbs out in formal drills but in informal groups instead of 3, 5, or 7 bulbs for a more naturalistic effect. In larger areas, such as lawns, throw handfuls gently and plant them where they fall. If planting daffodils in lawn consider that the foliage should not be cut back for 6 weeks after flowering so the lawn will not be able to be mown during this time.

Cover ponds with a net to catch fallen 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. These fallen leaves will eventually turn to a mushy stinky silt in the pond and need clearing out, which is an unpleasant and awkward job that is best done a little as necessary. 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

Siberian Wallflower, Erysimum allionii

Siberian Wallflower, Erysimum allionii, Kirisame, CC BY-SA

Plant out any biennial plants sown earlier in the year and they will have a head start on those planted in spring time. If you didn’t have time to self sow then it should still be possible to buy plants now. These includes foxgloves, digitalis sp, wallfowers, Erysium 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 extra irrigation.

Relocating evergreen shrubs

While the soil is still fairly warm in early autumn it is a good time to relocate evergreen shrubs that may have outgrown their allotted space or be in the wrong place aesthetically. Identify where the plant is to be moved and water it well the day before relocation. If it is a well-established plant be aware that the root system may be quite extensive and will need careful teasing with a garden spade and fork to remove enough of a root ball for the plant to grow on. It is OK to sever some of the very thick or unmoveable roots with a sharp knife if it helps to free up a good network of roots for the plant as a whole. Replant the plant facing the desired direction in a pre dug pit that is half as wide as the root ball and with loosened soil at the base to give plenty of room for the plant to stretch out and breath. Water the shrub well and mulch the base with an organic mulch.

Dividing perennials

Dividing untidy and spreading clump forming perennials into smaller plants when they are not in active growth will reinvigorate them and keep their spread in check. 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, which are likely to be apparent in the parent plant. 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, 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. Add organic matter to the soil, firm the plants in and water well.

Collect seeds

Keep collecting seeds for sharing, storing or for planting next season. Consider the plants natural form of dispersal – popping seed pods, wind dispersal or attaching to clothes or fur with burrs for example. If it’s a popping capsule be aware that the lightest touch may send the seeds flying and be prepared for this. 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.

Gardening tasks in September

  • Keep the garden clear of damaged and diseased stems and build up of leaves in access areas.
  • 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. It may help to use a bulb planter for larger bulbs.
  • Begin the autumn tidy. Remove and destroy diseased foliage and clear large areas of fallen leaves if they are in access areas and risk becoming slippery mush. Aim to leave healthy stems and seedheads on plants and leave a few piles of leaves in less disturbed areas.
  • 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.
  • 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.
  • Plant new perennial plants. Be aware of their eventual height and spread when deciding on an appropriate spot to put them.
  • Relocate evergreen shrubs.
  • Divide perennials.
  • Give hedges a final trim before winter.
Elaine Hughes

ELAINE HUGHES

Elaine is an RHS Gold Medal award winning landscape designer with a special interest in creating beautiful and functional spaces that are also as biodiverse and sustainable as possible. She has designed a wide range of projects including private gardens, community gardens, public areas, schools and community sites.