How to remove honeydew from your balcony, garden furniture and car

The garden table is sticky, the glass balustrade is covered in tiny droplets and a tacky film gleams on the car roof: anyone who lives or parks under a lime tree in summer knows the feeling. To remove honeydew without scratching surfaces, you mainly need two things – lukewarm water and a little patience.

The problem peaks in June and July. The five steps below show how to clean balconies, glass, garden furniture, fabrics and cars, and how to stop black sooty mould from forming.

Where the sticky film comes from

Aphids and other sap-sucking insects feed on the sap of leaves. It is rich in sugar but low in protein. To get enough protein, they suck up large amounts and excrete the surplus sugar as honeydew. The fine droplets drift down like drizzle onto everything beneath the tree crown.

Lime trees (lindens) are the best-known culprits, but maples, birches and some fruit trees produce it too. In warm, dry weather aphids multiply quickly and the layer gets thicker every day. A heavy shower washes some of it away; in hot weather it simply dries in place.

Over time, sooty mould fungi settle on the sticky film. They form a black, greasy coating which is mostly a cosmetic problem, but the longer it stays, the harder it is to shift. The sugar also attracts ants and wasps.

1. Act early and get prepared

Fresh honeydew comes off almost effortlessly with a wet cloth; after a few hot days it is hard and full of dust. In peak season, plan two short rounds a week rather than one big session a month.

What you need: a bucket of lukewarm water, a few drops of washing-up liquid, soft sponges or microfibre cloths, a soft brush for grooves and joints, and a second cloth for drying. The Swiss consumer protection foundation (Stiftung für Konsumentenschutz) recommends simple household remedies such as soap instead of lots of specialist products. Sugar dissolves in water – more chemicals bring no benefit here.

2. Remove honeydew from the balcony: floor, railing and glass

Start at the top and work your way down: railings and glass first, then window sills and finally the floor.

• Glass balustrades and windows: Wet generously with soapy water, leave for two to three minutes, wipe with a soft sponge and dry with a squeegee so no limescale spots remain.
• Metal and plastic railings: Same method; go over the grooves with the brush.
• Balcony floor: Sweep up leaves and blossoms first, then mop with a damp cloth. Don't tip out buckets of water – it will drip onto the balcony below.

On terraces and patios, water from the floor drains often flows untreated into streams and rivers. The platform of the cantonal energy and environment offices points out that in a separate sewer system rainwater from squares and terraces goes straight into nature. So empty your cleaning water into the sink or toilet.

3. Clean garden furniture, parasols and cushions

How you clean the furniture depends on the material:

• Plastic and metal: Warm soapy water and a soft sponge, then rinse with clean water and dry. No scouring pads, or the surface will turn dull.
• Wood: Brush along the grain with a soft brush, use little water and let it dry thoroughly. Oiled wood may need a fresh coat of care oil afterwards.
• Fabrics: Wash cushion covers according to the care label. Treat parasol and awning fabric with a soft brush and lukewarm soapy water, and let it dry completely before closing it.

You'll find more tips by material in our guides clean garden furniture and clean a parasol.

For high spots such as awnings or canopies, use a stable step ladder. The Swiss Council for Accident Prevention (BFU) advises using a safe step ladder with a safety bar instead of chairs or boxes.

4. Remove honeydew from your car

With a car it pays to act especially quickly. The longer the sugary film sits in the sun, the harder it gets, and dull patches can remain on the paintwork.

• Go to a car wash or self-service wash bay, where the waste water is drained off properly.
• Soak the car thoroughly with water first so the sugar dissolves before you use a sponge or brush.
• Never rub the deposit off dry – the dust and pollen in the film will scratch the paint.

Don't wash your car with detergent in the street or on the driveway: the water runs through the street drain into rivers and lakes. Your commune can tell you what is allowed on private property.

5. Prevention: less honeydew, less work

You can't prevent honeydew entirely, but you can greatly reduce how much you have to clean off:

• In June and July, don't park under lime or maple trees.
• Place the table and chairs outside the tree crown or cover them with a protective cover.
• Keep the parasol closed in its cover and bring cushions indoors.
• Hose down balcony plants infested with aphids using a strong jet of water; for heavy infestations, ask at a garden centre.

If a neighbour's tree or one belonging to the building hangs over your balcony, don't cut it back yourself as a tenant. Speak to the property management or the caretaker.

Common mistakes

• Rubbing dry: The dust in the sugar film scratches glass, paint and plastic.
• Waiting too long: Sooty mould takes hold and the deposit hardens.
• Harsh cleaners: Thinners, methylated spirits or oven spray are unnecessary and can damage surfaces.
• Water down the outdoor drain: Soapy water belongs in the sewer, not in the stream.

Priority Clean editorial teamOur cleaning team from Alberswil, Canton of Lucerne, shares hands-on experience from move-out, house, office and window cleaning across Central and Northwestern Switzerland.