Why Autumn Is the Most Valuable Season in the Garden

By late September the garden is winding down, but this is not the moment to hang up your trowel. The weeks between the first falling leaves and the first hard frost are the most productive of the year for getting ahead. Soil is still warm, rainfall is reliable and plants are settling into dormancy rather than pushing out new growth. Every job you complete now is one you will not be doing in a cold, muddy March.

Think of it as banking time. A few focused weekends in October and early November will pay you back with healthier plants, cleaner borders and a spring that feels far less frantic.

Clear Leaves and Tidy Up Before They Smother Everything

Fallen leaves look charming for about a fortnight, then they start doing damage. A thick, wet layer on a lawn blocks light and air, encouraging moss and fungal disease, while leaves piled around the crowns of perennials can cause rot over winter.

• Rake lawns every week or so during peak leaf fall, and don't leave piles sitting on the grass for days.
• Sweep leaves off paths, decking and steps. Wet leaves are genuinely slippery and cause a good number of autumn tumbles.
• Clear gutters, drain covers and water butts so heavy rain has somewhere to go.
• Don't bin the leaves. Pack them into bin bags punched with a few holes, or a wire cage, and leave them for a year to make leaf mould — one of the finest soil conditioners you can get for free.
• Leave a small undisturbed pile in a quiet corner for hedgehogs, frogs and overwintering insects.

Cut Back Spent Perennials — but Not All of Them

Herbaceous perennials such as hardy geraniums, crocosmia and phlox will have finished by now. Cutting them back to about 5cm above ground tidies the border and removes hiding places for slugs and snails.

However, resist the urge to be too neat. Seedheads on sedum, echinacea, teasel and ornamental grasses feed birds through the winter and hold frost beautifully. Leave them standing until late February, then cut them down before new growth starts. Any plant that showed signs of mildew, rust or black spot should be cut back and the debris binned rather than composted, to stop problems overwintering in your compost heap.

Improve the Soil While It Is Still Workable

Autumn is the ideal time to dig over empty beds, because the winter frosts will break down clods and improve structure for you. Spread a generous layer of well-rotted manure or garden compost over the surface and let the worms do the digging.

• Plant garlic and autumn onion sets now for a head start next summer.
• Plant bare-root trees, roses, hedging and fruit bushes from November onwards — far cheaper than potted plants and they establish quickly.
• Divide congested perennials such as daylilies and hardy geraniums while the soil is warm.
• Empty spent summer containers and refresh the compost rather than reusing tired stuff full of vine weevil grubs.

Protect Tender and Half-Hardy Plants

The first frost in most of the UK arrives somewhere between late October and early December, and tender plants need protection well before it lands. Move pots of citrus, olives, agapanthus and pelargoniums into a greenhouse, conservatory or sheltered porch while they are still actively growing.

Lift dahlias and cannas after the first light frost blackens the foliage. Cut the stems back to around 10cm, shake off the soil and store the tubers upside down for a week to drain, then pack them in dry compost or vermiculite in a cool, frost-free shed.

For plants staying put, wrap tree ferns and bananas with fleece or straw, and tie it securely. Push a handful of straw around the crown of tender perennials and cover with a cloche or a generous mulch. Raise terracotta pots onto feet or bricks so they drain freely — water trapped in a pot that freezes will crack it. Bubble wrap around the outside of pots helps, but leave the drainage hole clear.

Don't Forget the Lawn, Greenhouse and Tools

Autumn lawn care makes an enormous difference to how the grass looks next spring. Scarify to remove thatch, aerate with a garden fork to relieve compaction, and apply an autumn lawn feed that is low in nitrogen and high in potassium and phosphorus. This encourages strong roots rather than soft top growth that frost will damage. Keep mowing, but raise the blades gradually and stop altogether once growth slows.

Give the greenhouse a thorough clean while it is empty — wash the glass inside and out to let in maximum winter light, and clear debris from the floor to remove overwintering pests. Insulate with bubble wrap if you plan to overwinter tender plants, and ventilate on mild days to prevent mould.

Finally, spend half an hour on your tools: clean off soil, sharpen blades, oil metal parts and drain the hose. Clean, sharpened tools make winter pruning a pleasure rather than a chore. Do all of this well, and when spring finally arrives you will be planting and sowing while everyone else is still clearing up last year's mess.