October in the garden: the month's jobs before the first frosts
In October, the garden does not fall asleep: it changes pace. Asters and Japanese anemones still steal the show, the trees begin to drop their leaves, and somewhere between two fine days, a clear night will lay the first frost on the lawns. The whole month revolves around that moment. What is tender must be under cover before it; what is hardy, on the contrary, takes advantage of the still-warm soil to settle in.
In September, we prepared for spring with bulbs (in French). October is the month of the big tidy-up: bringing in, dividing, recycling, planting. Here, in the order the climate will impose them, are the jobs that really matter.
The October calendar: a race against the first frost
The Royal Meteorological Institute of Belgium (RMI) sets the scene. At Uccle, the normal daily mean temperature drops from about 13 °C at the start of the month to 8 °C at the end, with normal minimums of 3 to 8 °C depending on the region. In central and low Belgium, the first frosts usually appear during the month; in the Ardennes valleys, they come earlier and more regularly. According to the RMI, October is also the month when the winter storm season begins, which matters for large shrubs in pots and for plant supports.
In practice, this gives a simple plan of action. Early in October, finish the jobs that need warm soil: the lawn, dividing perennials, planting container-grown shrubs. As soon as the forecast announces nights close to 0 °C, bring tender potted plants indoors. After the first frost, lift dahlias, cannas and gladioli. And throughout the month, rake up leaves where they get in the way… and leave them where they are useful.
A calendar reminder: the clocks go back to winter time on Sunday 25 October 2026. One hour less of gardening in the evening, so plan ahead.
Bringing tender plants in at the right time
Mediterranean and tropical plants grown in pots (citrus, oleanders, bougainvilleas, daturas, houseplants put outside for the summer) do not wait for frost to suffer. Many tropical plants react as soon as nights drop below 10 °C: yellowing leaves, stalled growth. The safest course is to bring them in during a mild, dry spell rather than in a rush on a frosty evening.
Before bringing them in, check the undersides of the leaves and the bottom of the pots: scale insects, aphids and slugs love a free trip to a heated conservatory. A shower (for plants that tolerate it) and a cleaned pot prevent many infestations in the middle of winter. As for choosing the shelter, between a cold conservatory, a light garage and a heated room, it all depends on the plant: we cover the different situations in detail in our guide to overwintering garden plants (in French).
Fuchsias deserve a special mention, because they fall into two camps. Hybrids in pots or hanging baskets, the most spectacular, must spend the winter frost-free. Some so-called "hardy" fuchsias, such as forms of Fuchsia magellanica, can stay in the ground in a sheltered spot: their stems often freeze, but the rootstock sprouts again in spring if protected by a good mulch.
Dahlias, cannas, gladioli: lift after the first frost
Here, patience pays off. Do not lift dahlias (in French) on the first cool days: wait until the first frost blackens the foliage. The Royal Horticultural Society (RHS) places this moment, depending on the year, between September and November. The tubers will have used every day of growth to build up their reserves.
The method recommended by the RHS takes just a few steps. Cut the stems to about 5 cm from the base, lift the clump with a garden fork, keeping well away so as not to damage the tubers, remove the soil, then leave the tubers to dry upside down for a few weeks: the water in the hollow stems drains away instead of rotting the crown. Then store them in boxes, buried in sand, dry compost or dry potting mix, in a cool but frost-free place, not below 4 °C: a garage attached to the house or a well-insulated garden shed will do.
Cannas follow almost the same path: stems cut to 5 cm, rhizomes cleaned, then stored in sand, coir or vermiculite with the crown just showing, keeping the medium barely moist. Tuberous begonias are treated like dahlias, gladioli like other bulbs to be stored dry.
Can dahlias be left in the ground? In a sheltered, well-drained garden in low Belgium, many gardeners do so successfully, under a mulch at least 5 cm thick (straw, compost, shredded bark), as the RHS also suggests for mild areas. But it is a gamble: a wet winter rots tubers more surely than a cold one. On clay soil or in the Ardennes, it is better to lift them.
Dividing perennials while the soil is still warm
October is one of the best times to rejuvenate summer-flowering perennials that are bare in the centre or flowering less. According to the RHS, division works best when the plant is not in active growth, and it can be done either in spring (March to May) or in autumn (September to November). Most perennials benefit from division every two to three years.
The technique is simple. Lift the clump with a garden fork, shake off the excess soil, then split it according to the type of root: by hand for fibrous roots, with two forks back to back used as levers for large clumps, with a knife or spade for fleshy crowns. Each division should keep three to five healthy shoots. Replant immediately and water well, even if the soil is moist: the aim is to remove air pockets around the roots.
Two exceptions avoid many disappointments. Autumn-flowering perennials, such as asters or Japanese anemones (in French), are still in full bloom: divide them in spring instead. The same goes for slightly tender perennials, which re-establish better as the soil warms up. Bearded irises, for their part, are divided after flowering, in summer.
Planting while the soil is warm: shrubs, perennials, tulips
October soil retains summer's warmth while the air cools and the rains return. It is the ideal combination for rooting: a plant set out now develops its roots all winter without having to fight drought. Container-grown shrubs and perennials find their best planting window of the year here. For trees, shrubs and roses sold bare-root, the season starts in November, when the nurseries lift them; the Belgian and French saying for St Catherine's Day (25 November), "every piece of wood takes root", is more than a figure of speech.
As for bulbs, crocuses, daffodils and grape hyacinths (in French) should already be in the ground, but there is still time to plant them in October. Tulips are in no hurry: the RHS even advises planting them late, until November, once the soil has cooled, which reduces the risk of tulip fire (Botrytis tulipae), a fungal disease that distorts and spots the foliage.
For a natural effect with the following season's bulbs, don't forget the colchicums and autumn crocuses (in French) flowering right now: mark where they are, as their leaves will only appear in spring and they are easily forgotten when digging.
Fallen leaves: a treasure not to be burned
Every autumn, tonnes of leaves go to the recycling centre when they could produce one of the best soil improvers there is: leaf mould. The RHS gives the recipe. Collect the leaves, moisten them, then pack them either into large bin bags pierced with a few holes, or into a chicken-wire enclosure held up by four stakes. Allow about two years to obtain a fine, dark leaf mould.
Not all leaves are equal. According to the RHS, oak, beech and hornbeam leaves break down easily and give an excellent product. Thick leaves (sycamore, walnut, horse chestnut, sweet chestnut) are best shredded first, for example by running the lawnmower over them. Evergreens (holly, aucuba, cherry laurel) and conifer needles are better on the compost heap or kept separate: needles take two to three years to decompose.
Before two years, leaf mould serves as a mulch or soil improver around borders and shrubs. After that, it becomes fine enough to use in a seed-sowing mix, combined with sand, compost and soil. In the borders themselves, a layer of leaves left in place protects the soil and feeds earthworms; remove them mainly from lawns, paths (where they become slippery) and the hearts of rosette plants, which rot underneath.
A less tidy garden for overwintering wildlife
The big autumn clean-up, with stems cut to the ground and bare borders, is less and less recommended. The hollow stems and dry seed heads of perennials shelter insects that spend the winter there, the seeds feed birds (goldfinches on echinaceas, tits on sunflowers), and frosted silhouettes of grasses and sedums are among winter's finest sights. You can simply cut back what is diseased or collapsed and keep the rest until the end of winter. The same logic applies to roses: no hard pruning now, just shorten the long stems the wind might rock and loosen. On the other hand, now that nesting birds have left, it is the right time to empty and clean nest boxes.
The hedgehog is now looking for a shelter to hibernate. According to Natagora, it goes into hibernation as soon as the temperature drops below 10 °C and wakes around April; in practice, the scarcity of insects and the animal's weight also matter, and many hedgehogs only settle in for good in November. A pile of dead leaves at the foot of a hedge or against a log pile makes a perfect nest. Hence a simple rule: never burn a pile of leaves or branches without first taking it apart, and check under hedges before using a brushcutter. Natagora also points out that a 10 cm gap under a fence is enough for a hedgehog to move from garden to garden, and advises running a robotic mower (in French) only during the day, between 10 am and 5 pm.
The lawn: last chance to get it back into shape
For the RHS, September and October are the two key months for lawn care, because grass recovers quickly from the work while the soil is warm and moist. Start by scarifying with a spring-tine rake, in two crossing passes, to pull out the thatch: this layer of moss and old grass stops water reaching the soil. Next, aerate compacted areas with a garden fork, as deep as possible, with holes 10 to 15 cm apart; aerating every two or three years is enough.
The RHS then recommends a top-dressing (about 2 to 3 kg per m², brushed into the holes), overseeding bare patches, and a special autumn fertiliser, low in nitrogen, spread just before rain is forecast: it promotes roots rather than leaves. Avoid nitrogen-rich spring fertiliser, which would produce soft grass that is very susceptible to winter diseases.
In the vegetable garden and orchard: harvest, sow, protect
The last squashes should be harvested before the frosts, with a piece of stalk, then left for a few days in the sun or in a dry place so their skin hardens; this way they will keep all winter. On cleared beds, don't leave the soil bare: winter rains wash nutrients out of uncovered soil. A mulch of leaves or a green manure will do. Phacelia can be sown until the end of summer; in October, turn instead to green manures that withstand winter, such as rye.
In the orchard, October is the main month for picking keeping apples and pears: pick them when the fruit comes away with a simple twist, keep only unblemished fruit, and store it somewhere cool, without the fruits touching. It is also time to plant autumn garlic (shallots, which are more sensitive to winter wet, are mostly planted in spring), and to collect seeds of annuals you want to see again next year, such as nasturtium (in French): keep them well dried, in a labelled paper envelope, never in a plastic bag where they go mouldy.
Houseplants switch to winter time
Indoors, too, the season changes. Light decreases sharply: the RMI records a normal sunshine duration of about 113 hours for October at Uccle. Houseplants slow their growth and drink less. It is time to move them closer to the windows, clean their leaves so they catch what little light there is, and water less often. Overwatering in winter kills far more houseplants than neglect.
Stop feeding most species until spring, and move plants away from radiators as they come back on: the hot, dry air rising from a radiator dries the leaves and encourages red spider mite. If you used the summer to root cuttings in water (in French), pot them up without delay, before the days get even shorter.
October at a glance
| When | What |
|---|---|
| Early in the month | Scarify, aerate and overseed the lawn; divide summer perennials; plant container-grown shrubs and perennials |
| Before nights close to 0 °C | Bring tender potted plants indoors, after checking for pests |
| After the first frost | Lift dahlias, cannas, gladioli and tuberous begonias; dry them and store frost-free (above 4 °C) |
| All month | Rake leaves off lawns and paths and turn them into leaf mould; leave dry stems in the borders |
| End of the month | Plant tulips (until November); prepare for planting bare-root roses and shrubs in November |
| Indoors | Move plants closer to the light, water less, stop feeding |
October lacks the sparkle of May, but it is the month that decides the next season. A dahlia lifted in time, a clump of perennials divided, a bag of leaves set aside: these are discreet gestures, and they are the ones you find again in spring.
Sources
- Royal Meteorological Institute of Belgium (RMI), "Climat général en Belgique : mois après mois, octobre", meteo.be
- Royal Horticultural Society, "Overwintering tender plants: lifting or mulching", rhs.org.uk
- Royal Horticultural Society, "Perennials: dividing", rhs.org.uk
- Royal Horticultural Society, "Leaf mould", rhs.org.uk
- Royal Horticultural Society, "Lawn care in autumn", rhs.org.uk
- Natagora, Réseau Nature, "Accueillir le hérisson" fact sheet, natagora.be