Gardening Tasks for Mid Autumn

Garden borders

Mid autumn is the best time for planting most herbaceous perennials, except in cold wet areas. If planting out during a wet spell, lay short boards over the ground and work from these to avoid trampling down the soil.

Plant out hardy perennials raised from seed as soon as possible so that they have time to become established before winter.

Tidy beds and borders, but cut back faded growth only if it looks unsightly. Continue dead-heading and keep down seedling weeds by hoeing in dry weather.

Divide and replant old clumps that finished flowering in early summer, but leave soft-leaved types such as pyrethrum and achillea until early spring.

With new beds and borders planned for planting up in spring, dig the ground thoroughly now if not already done.

Dig over old borders which need a complete overhaul if this was not done in late summer. Dig up all growth and shake the earth off the roots. Discard all but healthy plants or any divisions which are to be replanted.

Then dig deeply and manure as for bare ground, making sure that all the roots of any perennial weeds are picked out and destroyed. Green annual weeds can be dug in, but turn them upside down and cover with at least 23cm (9in) of soil.


Prepare for over-wintering as the plants stop flowering. Many modern varieties — especially Koreans — will survive an average winter outdoors in southern England, provided the soil is well-drained and not infested with slugs. Clear away any surrounding debris and remove dead leaves and flowers, but leave the top growth intact until spring.

Elsewhere, cut the top woody growth down to about 15cm (6in) and remove any soft green shoots at ground level. Lift the stools and label them, then wash them thoroughly in cold water and bed them in a cold frame protected from frost, or in compost-filled boxes in a greenhouse.

Annuals and biennials

If frosts arrive late and the weather is mild, leave summer bedding plants such as marigolds, begonias and pelargoniums until there are no more flowers on them. Otherwise, remove them as soon as possible.

Remove annuals from borders where biennials such as wallflowers and forget-me-nots are to provide a spring display. Plant these during mid autumn while the soil is still warm enough to prevent damage from severe frost or cold east winds.

Do not manure beds or borders for spring-flowering bedding plants. Instead, work bone-meal into the top 15cm (6in) of soil at the rate of about 100g (4oz) per sq m/yd at the time of planting.

If desired, sow sweet peas directly into the ground outdoors as soon as possible, but this method is suitable only for naturally-grown plants in mild districts with well-drained soil. Treat the seeds with a proprietary fungicidal dressing and sow at the rate of 10g(1/3oz) of seed for a row 3m (10ft) long. Alternatively, sow sweet peas in pots or boxes by the middle of mid autumn and place in a cold frame. Remove the frame lights when the seedlings appear.

Bulbs, corms and tubers

Complete the planting of spring bulbs and start planting tulips and hyacinths. Hoe beds of newly planted daffodils, except in the mildest areas where shoot growth may have started. Alternatively, spray with a contact herbicide to destroy weed seedlings.

Lift tender summer-flowering bulbs, such as acidanthera, chincherinchee, schizostylis and sparaxis. In cold districts, take inside tubs of amaryllis, crinums and nerines for the winter.

After lifting bulbs, dry them as quickly as possible to prevent rotting. Place in shallow boxes in any warm spot. After a few days, separate the bulbs and corms from the debris and store them in a cool dry, frost-free place.

Cut down dahlias to about 15cm (6in) above the ground as soon as the first frost blackens the plants. Lift the tubers carefully, remove as much soil as possible and then stand them upside down in a frost-free place for about a week to allow the sap on the stems to dry out. Dust the crowns with sulphur before storing.

Lift gladioli corms when the leaves turn brown. Cut off all but 12mm (1/2in) of the main stem and leave the corms to dry for about a week. Store them in trays in a dry and frost-proof place.

Plant lilies, staking late-flowering types which are prone to wind damage. Bury the bulbs to a depth of two and a half times their height. If the soil is alkaline or very heavy, plant less deeply.

Rock gardens

Plant alpine seedlings or rooted cuttings by the third week of mid autumn, except for pot-grown plants which can go in at almost any time. When moving established plants to a new site, retain plenty of soil on the roots.

Water the plants if the soil is dry. Protect woolly or hairy-leaved plants from winter wet by covering with small sheets of glass supported on wire or metal cleats.

Renew the writing on labels that are becoming difficult to read, otherwise winter rain will make them totally illegible.

Scatter slug pellets if the weather is damp, paying particular attention to the ground close to evergreen, trailing and shrubby plants, or rough grass.

Water gardens and pools

Spread a net over the pool to catch falling leaves, clearing up the debris every week or so. Towards the end of mid autumn, thin out underwater oxygenating plants and remove old water lily leaves.

If the water is dark green or brackish, drain off half the volume and replace with fresh water. While the pool is half drained, remove old foliage and debris but leave most of the mud, which contains aquatic insects and the resting buds of some plants.


Prepare the ground for new roses which are to be planted in late autumn. Double-dig new beds, incorporating plenty of organic matter into both spits (spade depths), plus bone-meal at the rate of 50100g (2-4oz) per sq m/yd. On light soils use materials such as chopped turf, hop manure, leaf-mould and sawdust. Lighten medium or heavy soils by adding clinker, gravel, pulverized forest bark or straw. If the topsoil is less than two spits deep, add more topsoil or dig out a hole at each planting site and mix in the materials listed above.

If the soil is strongly acid, spread lime over the surface at the rate of a good handful per sq m/yd.

Spray roses with a systemic rose insecticide if greenfly appear. In areas prone to fungal diseases continue to spray fortnightly with rose fungicide.

Shrubs and trees

Towards the end of mid autumn start planting hardy deciduous shrubs and trees in well prepared ground. Firmly stake newly planted standard trees. Do not plant in frosty or wet weather or when a strong north or north-east wind is blowing. If shrubs are delivered during bad weather, unpack them and stand in a dry shed with straw or sacking around the roots until the weather improves.

If bad weather has set in or planting cannot be done for a few weeks for other reasons, insert the shrubs in a V-shaped trench so that their roots are covered, and firm down the soil. The plants should survive until spring.

When moving evergreens, try spraying the entire plant with a special aerosol moisture-retention spray — often sold for spraying Christmas trees to reduce needle-drop. This helps to prevent wilting and the coating washes off after a month or so. It can also be used for deciduous trees which have to be moved while still in leaf.

Take 30cm (1ft) long hardwood cuttings of Aucuba japonica, Buddleia davidii, deutzia, escallonia, spring-flowering honeysuckle, philadelphus, spiraea, tamarisk and weigela. Root in sandy soil in a cold frame or in the open.

Propagate Daphne cneorum and fothergilla by layering young shoots in pots of compost, plunged around the parent plants.

Separate rooted suckers of celastrus, Forsythia suspensa, poplar, Rhus typhina, robinia and snowberry from their parent plants. Replant in their permanent growing positions, staking where necessary. Divide and replant overgrown Euonymus fortunei and spiraea.

18. June 2011 by Dave Pinkney
Categories: Garden Management, Gardening Calendar | Tags: | Comments Off on Gardening Tasks for Mid Autumn


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