Here are your gardening jobs for the month – with added links if I have more information on the subject. They are all still relevant to do now if you’ve fallen behind or if the weather’s been bad.
Plant bare-root deciduous hedging plants, trees and shrubs promptly, before they dry out. They can be heeled in for a short period if weather conditions are bad.
Lightly prune bush roses to prevent wind rock, as they are usually shallow rooted. Climbing roses should be pruned now at the very latest.
Tie wall shrubs and climbers on to their supports to protect them from wind damage. Prune off any growth that refuses to be trained.
Take hardwood cuttings of ornamental shrubs such as Cornus, Euonymus, Forsythia, Hydrangea, Ilex, and Salix.
Put fallen leaves on the compost heap or into separate pens for rotting down into leaf mould.
Plant lilies in pots to be brought inside next spring to force them into an early display or left outside to flower naturally in summer.
Tulips can now go in. Species tulips naturalise, but showier varieties are best treated as bedding and replaced every year.
Apply an autumn mulch to protect plants that are borderline hardy such as Agapanthus, Kniphofia (red hot pokers) and Phygelius. The plants’ own leaves, e.g. Kniphofia, can be tied up and used as protection for the crowns underneath.
A wet autumn can make clay soils unworkable until spring. Mulching will help to improve and maintain soil structure.
Lift and store dahlias, cannas and tuberous bedding begonias that have been hit by the first frosts.
Make sure that you have not forgotten any of your tender plants and bulbs – they need to be brought inside or into a heated greenhouse over the winter.
Protect alpines from the wet, if you have not done so already.
In mild weather, weeds will still appear. Hoe regularly to keep them in check.
Group tropical houseplants on trays of wet gravel for more humidity when the central heating comes on.
Pelargoniums (geraniums) can be cut back, de-leaved, watered less, not fed, and kept relatively dormant and just moist, over the winter. Re-potting, watering and feeding in the spring will bring them back into active growth. They should be kept at around 10°C (50°F) while dormant, although mine have endured much lower temperatures than that.
When bringing plants indoors, check them for pests and diseases. Poor-looking plants can always be tipped out of the pot to check their rootballs for signs of over or under watering, or for soil pests like vine weevil larvae.
Check any bulbs (e.g. hyacinths and ‘Paper White’ daffodils), being forced in darkness into early growth. When they have made about 2.5cm (1in) growth, bring them into a light, cool room or frost-free greenhouse to grow on. When flower buds appear, they can be brought into warmer rooms.
It is an ideal time to plant roses. Avoid planting in areas where roses were previously growing otherwise new introductions may suffer from replant diseases (rose sickness).
This is also a good time to transplant trees and shrubs growing in unsuitable positions. However, if they are more than a couple of years old, you are unlikely to be able to remove an intact enough rootball to ensure the plant’s survival in its new position, and you may be best advised to leave well alone.
Check tree stakes and ties are secure and will withstand the winter weather; make sure that ties are not strangling trunks or branches – they may need loosening.
Coral spot is often noticed once the leaves have fallen from deciduous hedges, shrubs, and trees. This problem can be connected with poor ventilation and congested, un-pruned twiggy growth (as found inside clipped hedges), but it is more a sign of unsuitable conditions than a serious pathogen in itself.
Now is the last chance to plant out winter bedding. You could try wallflowers, forget-me-nots, Bellis, Primula, Viola (winter pansies) and other spring bedding plants, planting them into well-prepared ground, or pots of suitable compost.
Cut down faded herbaceous perennials and add them to the compost heap, or leave them as they are, as the stems provide hibernation places for insects. Penstemons are best left (except for deadheading) until the spring. In mild areas, they can carry on flowering into early winter. The old faded stems will help to protect the crowns from cold. Mulching over the crowns in colder areas will also help.
Hellebores rarely flower naturally by Christmas, despite their common name of Christmas rose. They can be encouraged to flower a little earlier, if you want, by covering them with cloches, potting them up and bringing them into a warm greenhouse, or placing them on a windowsill inside the house.
Large tubs that are at risk of cracking in the frost should be covered with bubble wrap, hessian or fleece, to insulate them over the winter.
If barley straw bales or pads were used to reduce algae during the summer months, these can now be removed and added to the compost heap. Let them sit by the edge of the pond for 24 hours before composting, so that pond insects can find their way back into the water.
Complete cleaning out spent crops from the greenhouse, if not yet done. Clean and disinfect the greenhouse structures with Jeyes Fluid or Citrox.
NOTE – as the gardening year winds down, work according to what the weather will let you do. If you’ve fallen behind, check the last couple of weeks of jobs – you probably still can do some of them.
You can still order and plant container trees and shrubs, and large semi-mature specimens for planting later in the winter.
Shrubs normally pruned hard in spring – such as Buddleja davidii, Cornus alba, and Lavatera – can be cut back by half now, to prevent wind rock.
Tree and shrub seeds and berries can be harvested and sown, once they are ripe.
Garden hygiene is vital to help control and prevent disease. Rake up and NEVER compost infected leaves, such as black spot on roses, or scab on apples and pears.
Toadstools are often visible now, especially honey fungus. The toadstools appear on, or at the bases of, affected trees. Similar toadstools in beds or lawns are more likely to be harmless fungi that live on dead material and pose no threat.
Lift and divide overgrown clumps of herbaceous perennials, or leave them until spring. Cover borderline hardy plants with fleece sacks to protect them from the worst of any winter weather, especially if still young.
Ornamental grasses and bamboos can be cut back and tidied up.
Root cuttings can be taken now and throughout winter. Papaver (perennial poppies), Verbascum (mullein) and Phlox are suitable examples.
Digging the soil will expose pest larvae and eggs to birds and frosts, as well as clearing weeds and improving soil structure.
Around ponds, remove the last of the dead foliage. You can still divide hardy waterlilies and cut back overgrown marginal plants.
Tender plants should already have been brought into a frost-free greenhouse until the risk of frost has passed.
Protect newly planted trees, hedges, and shrubs from wind and cold – a netting windbreak should suffice.
Pack straw or bracken around deciduous plants to protect them from frost. A frame with clear polythene stretched over it can do a similar job without blocking light from evergreens, but don’t let the polythene touch the foliage.
Pruning and renovation of some deciduous trees, shrubs, and hedges, such as beech, can be carried out from now – you can see the framework more easily. Exceptions are tender plants, and also Prunus species (e.g. ornamental cherries, plums, and almonds), as these are vulnerable to silver leaf if pruned in the autumn or winter. Evergreens are best left until the spring.
When pruning trees and shrubs, examine branches for signs of disease. Small cankers, dieback, and rotten, hollow stumps are best removed before they spread.
If your trees are too large for you to manage the pruning alone, then you may need a tree surgeon. Otherwise, take care not to damage the tree when sawing off thicker branches.
If it snows, brush it gently off the branches of conifers. Heavy snowfall can splay branches and spoil the shape of the tree.
Phytophthora root rots can cause dieback on mature trees and shrubs. Wet winter weather and poorly drained soils are likely to encourage this problem on susceptible woody plants. Look out for crown rot and brown rots (sclerotinia) on dormant perennials, especially if you are on a clay soil.
Watch out for downy mildew and black spot on winter pansies.
Indoors, pot up Hippeastrum (Amaryllis) bulbs, and bring them back into active growth with regular watering and feeding.
Reduce watering and feeding of houseplants as the days shorten.
Cacti and succulents need a period of dormancy over the winter: keep them barely moist, and do not feed. Start them back into growth next spring. Christmas cacti can be managed in the same way as other cacti, or in reverse, for flowering at Easter or Christmas.