How do you get green algae off garden furniture?

Green algae is an environmental, not a furniture material issue, all are susceptible, so how do you get it off garden furniture?

We recently looked at how to rejuvenate weathered plastic garden furniture, and in that article, we touched on mould and mildew. It can be a problem here in the UK, especially with wood and plastic. We have the perfect climate for it in late spring and into the summer. It is not so common on our maintenance-free metal garden furniture but it can still form.

Mould and mildew love temperatures between 20°C and 30°C, factor in the rain we still get at this time of year, and you have the perfect breeding ground. In this article, we want to look at something that many mistake for mould or mildew but is in fact from a different biological group, and that is green algae.

Like mould and mildew, green algae thrive in warm, damp, shaded areas. It is commonly found on any outdoor surface that’s exposed to moisture, such as garden furniture, plant pots, decking, paved patios, etc. It can spread quickly in warm and humid conditions, especially if there is a lack of sunlight and ventilation, such as you might find in a north-facing garden, a garden with lots of tall trees, on a covered patio, in a garden shed, or under a non-breathable furniture cover.

The difference between moulds, mildew and green algae is as follows:

  1. Moulds
    Moulds are multicellular fungi that reproduce by producing spores. Depending on the species, they often appear as fuzzy or powdery growths and can be black, green, or orange.

  2. Mildew
    A type of mould that specifically grows on surfaces like outdoor fabrics, such as parasols, awnings, cushions, etc. It tends to have a powdery texture and can be white, grey, yellow, or brown.

  3. Green Algae
    Are single-celled or multicellular organisms belonging to the plant kingdom. They can be found in various environments, including freshwater, saltwater, and damp terrestrial habitats.

While they share the characteristic of thriving in moist conditions, green algae are distinct from moulds and mildew in their taxonomy. However, the one thing they do all have in common is that they can be removed from garden furniture, and in this post, we want to focus specifically on the different methods we like to use to safely remove green algae from metal, plastic, and wooden garden furniture:

1. How to remove green algae off metal garden furniture

To safely remove green algae from your metal garden furniture, follow these simple steps:

  1. Solution
    Mix up a splash of car shampoo and warm water in a bucket. Avoid using bleach or any harsh chemicals, especially if the furniture has a painted or powder-coated finish that could be damaged.

  2. Wash
    Dip a sponge into the soapy water and wash the affected areas of the metal furniture thoroughly. Apply gentle pressure to loosen the algae growth and accumulated dirt or grime.

  3. Rinse
    After washing, rinse the furniture with a garden hose of a spray setting to remove any soap and algae residue. Make sure you rinse all surfaces and from in-between any latticework, to prevent algae from taking hold again.

  4. Repeat
    For stubborn algae growth on lighter-coloured furniture, you may need to repeat the cleaning process. Allow the furniture to air dry in the sun completely before using.

2. How to remove green algae from plastic garden furniture

To safely remove green algae from plastic patio furniture requires a few extra steps and a little patience, especially on lighter colours. Our go-to method is as follows:

  1. Solution
    Mix up a good splash of laundry detergent in a bucket of warm water. Avoid using undiluted bleach or any harsh chemicals, especially on coloured plastics, as they can cause discolouration or damage/dull the finish.

  2. Wash
    With a soft-bristled brush or sponge wash the furniture down, paying close attention to the areas affected by the algae. Ensure thorough coverage, especially on spots with heavy growth.

  3. Scrub
    Use the brush or sponge to scrub the areas gently where the algae has formed. Apply gentle pressure to loosen the algae without damaging the plastic surface. Pay attention to crevices, corners, and other hard-to-reach areas where algae may accumulate too.

  4. Leave
    Allow the laundry detergent solution to sit on the plastic furniture for a few minutes so it can break down the algae and loosen any other stubborn dirt and stains.

  5. Rinse
    Rinse the furniture with a garden hose with a spray nozzle to remove any remaining detergent and algae. Make sure to rinse all surfaces thoroughly, including underneath the furniture and any intricate detail or latticework.

  6. Repeat
    For stubborn algae growth or heavily soiled areas, you may need to repeat the cleaning process. The How to rejuvenate plastic garden furniture article we mentioned in the intro has a few other kitchen cupboard cleaning solutions (such as baking soda) you can try if laundry detergent doesn’t do the trick.

  7. Dry
    Dry off with a towel to prevent any watermarks and then leave in the sun to air dry completely before using.

3. How to remove green algae off wooden garden furniture

If your wood patio furniture is sealed and protected, then cleaning is simple, if not things can get a little tricky and a bigger restoration/repairs might be needed. To safely clean green algae off wooden patio furniture, follow these steps:

  1. Solution
    Mix up washing up liquid or a specialist wood cleaner in a bucket of warm water. Again, you should avoid using bleach or any other harsh chemicals on wood, as they can damage the surface.

  2. Wash
    Dip a soft-bristled brush or sponge into the cleaning solution and wash your furniture, paying close attention to any spots with heavy algae growth.

  3. Scrub
    Use the brush or sponge to scrub the algae, applying gentle pressure to loosen it without damaging the wood’s finish. Work in the direction of the grain to avoid marring the surface.

  4. Leave
    Allow the cleaning solution to sit on the wood for a few minutes to penetrate the algae and loosen any other stubborn stains.

  5. Rinse
    Rinse the furniture with a garden hose on spray to remove the cleaning solution and any algae residue.

  6. Dry
    After rinsing, leave the wooden furniture to dry completely in a well-ventilated area. Avoid leaving your furniture in direct sunlight for extended periods, as this can cause damp wood to warp or split.

How to prevent green algae from forming on your outdoor furniture

For our patio furniture range, after cleaning with warm soapy water, we recommend applying a light coat of car wax. A good car wax will contain hydrophobic ingredients that repel water and algae spores, helping water to bead and run off. This will help to prevent the algae from reforming and maintain your furniture's appearance and durability.

With plastic furniture, once clean, we recommend applying a protective coating such as a plastic furniture restorer, polish or spray. They are specially formulated for plastic surfaces, and whilst they’ll clean it, they will also create a barrier that helps repel moisture and algae spores, reducing the likelihood of new growth.

If you have wooden furniture that has been severely affected by algae or if the finish is damaged, then you may need to sand the surface to remove any remaining stains or discolouration. Once the wood is dry, apply a fresh coat of wood sealer or outdoor furniture finish to protect it from future algae growth and weathering.

As we always say on this blog though, prevention is better than the cure, and the following steps will stop it from forming:

  1. Clean
    Regularly clean your garden furniture to remove any dirt, debris, or bird droppings that algae can feed on.

  2. Dry
    Try and keep your garden furniture dry when not in use. Wipe down the surfaces with a towel after rain or dew, especially in shaded areas where moisture can linger.

  3. Sunlight
    Algae thrive in shady, wet environments, so move your garden furniture to an area where it receives sufficient sunlight throughout the day to inhibit algae growth by drying out surfaces and reducing moisture levels.

  4. Drainage
    Ensure that water drains away from your garden furniture and surrounding patio area effectively. Proper drainage will prevent standing water, which can create conducive conditions for algae growth.

  5. Cover
    Cover your garden furniture with waterproof breathable protective covers when not in use, especially during periods of heavy rain or when you're away for an extended period.

  6. Maintain
    Regularly inspect your garden furniture for any signs of algae growth or deterioration. Address any issues promptly to prevent them from taking hold.

By implementing Lazy Susan’s simple preventative steps, you can effectively reduce the likelihood of green algae forming on your garden furniture and keep it looking clean, well-maintained, and ready to enjoy this summer.

If you have any photos of your Lazy Susan Garden Furniture, we’d love to see a few for our Do Some Good charity campaign. You can tag us @LazySusanFurniture on Instagram or Facebook or Upload Here.

Share this article
Please enter these characters in the following text field.

The fields marked with * are required.