Autumn Garden Tasks: Bulbs, Clean-Up and Winter Preparation

Autumn garden tasks include bulbs, clean-up and winter preparation, because what you do now sets up the next spring.

Autumn work runs on the frost clock, not the calendar. Roots-first jobs such as trees, shrubs, bulbs and garlic belong in the weeks before the ground freezes. Tender tubers come out right after the first frost blackens the foliage, and drainage and clean-up should be finished before the soil is frozen or sodden. This guide gives the timing of each job, the soil temperatures and depths that matter, and what to leave alone.

It’s the autumn stop in the Seasonal Gardening guides, following Summer Garden Maintenance and leading into Winter Garden Care. The cold-night tactics themselves are in Frost Protection Methods.

Autumn at a glance

Find your autumn clock

A calendar month means little when first frosts range from September to December. Look up your average first frost date and count back from it. As a rough guide for the Northern Hemisphere, the first frost typically arrives as follows, varying by 2 to 4 weeks with altitude and local frost pockets.

In the Southern Hemisphere the whole year flips by about six months, so autumn runs from March to May and a zone 6 gardener’s October window becomes April. Zone describes winter minimum temperature, not frost timing, so treat the table as a starting point and trust your own recorded dates.

What to plant, in order

• Trees, shrubs and hedging first. Warm soil and returning rain let roots establish before winter. Water weekly through dry spells until the ground freezes, then mulch 5 to 8 cm (2 to 3 in) deep, kept clear of the trunk.
• Daffodils, then tulips. Daffodils want a head start on roots, while tulips planted into warm soil are more exposed to fungal disease. In heavy clay, set bulbs on a handful of grit.
• Garlic. Plant cloves pointed end up. Green shoots in autumn are normal and hardy. Choose hardneck types in cold zones and softneck in mild ones. Garlic typically needs several weeks of cold soil to form split bulbs, so planting it in a warm spell and leaving it be is fine.
• Perennials. Divide crowded clumps of spring and summer bloomers, replant at once and water. Leave late bloomers such as asters until spring in cold zones.
• Hardy crops. Where winters stay mild, sow broad beans and peas, and under cover sow lettuce, spinach and corn salad. For timing of staggered sowings see Succession Planting.

Lifting tender tubers and corms

Dahlias, cannas and tuberous begonias die when frozen tubers turn to mush. The first light frost blackens the foliage but rarely reaches tubers under 10 cm of soil, so there’s no need to rush. Leave plants until frost kills the top growth, because the plant is still feeding the tubers.

1. Cut stems to 10 to 15 cm (4 to 6 in) and label each variety.
2. Lift gently with a fork 20 to 30 cm out from the stem, so you don’t spear the tubers.
3. Shake off most soil and stand clumps upside down for a few days in a frost-free shed so water drains from the hollow stems.
4. Pack in boxes of barely damp bark, sand or wood shavings, with no tubers touching.
5. Check monthly. Remove rotten tubers, and mist lightly only if they begin to shrivel.

Leaves, clean-up and what to leave

See Garden Hygiene for how to sanitise tools after handling diseased material.

Cover the soil: mulch and green manure

Bare soil loses nutrients to winter rain and crusts under heavy downpours. Either spread 3 to 5 cm of compost and let worms pull it down, or sow a green manure that’s cut or dug in during spring.

Stay off wet beds. Walking on saturated soil squeezes out air, a problem covered in Preventing Soil Compaction.

Frost preparation and pruning

• Pots: raise terracotta on feet so it drains, because water that freezes in the clay splits it. Move small ones under cover.
• Taps and hoses: disconnect and drain hoses, shut off the outdoor supply and open the tap so trapped water has room to expand.
• Ponds: net leaves, and in freezing climates lift pumps out and store them in water.
• Pruning: remove dead, diseased and crossing wood. Hold the main pruning of roses and most shrubs until late winter, because autumn cuts push soft growth that frost kills.
• Tools: scrub off soil, wipe blades with an oily rag and sharpen secateurs now, so spring starts without a blunt-blade delay.
• Fruit trees: clear fallen fruit and fit grease bands in early autumn against winter moth.

When things go wrong

Why autumn garden tasks set up next year

Raking leaves feeds a leaf mould bin that improves soil and holds moisture, and a layer of compost on beds protects earthworm channels over winter. Planting garlic, onion and spring bulbs in cool soil temperature supports strong roots before frost. Cutting back diseased tomato and rose foliage reduces blight and black spot spores.

Lifting dahlia and tender geranium protects them from frost, and a cold frame or fleece shields lettuce and kale. Sowing a cover crop of clover or rye fixes nitrogen and prevents compaction on bare soil. A last feed of potash hardens fruit trees, but nitrogen encourages soft growth that frost kills. Which jobs matter most? Clear disease first, then mulch and plant bulbs, because you’ll find spring far easier. Your extension service lists your first frost date, which helps you plan.

How autumn garden tasks protect bulbs, beds and lawn before winter

Tulip and daffodil bulbs need planting 10 to 15 cm deep before the ground freezes, and crocus and allium suit the same window. Mulch protects rose crowns and reduces frost damage around hosta and fern. Compost feeds loam and improves clay, while leaf mould suits beds under birch and maple. Fallen leaves cause lawn rot, so you should rake them from grass within 2 weeks. Clover and grass recover well when you aerate compacted soil in autumn. Cut back peony and hosta that show blight, because spores spread from old leaves to new shoots. Garlic and onion sets need planting now, and broad bean and pea can overwinter in mild areas. Lavender tolerates a light trim, but hard pruning in autumn damages the plant. Tomato and pepper plants finish early, so you’ll pull them and add the remains to compost. Wet leaves hold slug and snail, and a tidy bed reduces both. Your extension service or the rhs lists the best bulb dates for your climate. The winter garden care guide covers what comes next.

Common mistakes

• Tidying everything. Bare beds and cut stems remove wildlife habitat and expose crowns. Clear only disease and mush.
• Planting tulips in warm soil. Fungal disease and early shoots follow. Wait until soil stays under 10°C.
• Lifting dahlias before frost. Tubers need the leaves feeding them. Wait for blackened foliage.
• Burying bulbs too shallow. They freeze, heave and flower weakly. Use three times their height.
• Leaving hoses connected. Ice splits taps and pipes. Drain and disconnect first.
• Composting blighted crops. Spores survive a cool heap. Bin them.

To recover after a hot summer, see Heatwave and Drought Garden Care.

Next steps

Prepare the cold season with Winter Garden Care, learn the cover materials in Frost Protection Methods, and review the year in Planning for Next Year. Back to the Seasonal Gardening guides.