We regularly receive questions about green algae on terraces, decking, garden furniture, cushions, and garden furniture covers. Green algae is indeed a point of irritation for garden enthusiasts, but it doesn't have to be. Because after reading this blog, you will know everything about green algae. We start with what green algae is and how it develops, then we explain how you can clean and remove it from your lounge set. We end with tips on prevention and avoiding green algae on your garden furniture, for example, with a lounge furniture cover.

What is green algae?

Green algae is an annoying phenomenon, but not difficult to remove with the right measures. You will find that the result is always very satisfying. What exactly is green algae? It consists of mosses and algae that thrive in shady, dark, and very moist areas. That's why green algae occurs almost exclusively in the autumn and winter months, when there is relatively more rain and the sun rarely shows itself. In fact, it's a weed that comes back annually. Sunlight is actually the best remedy against these mosses and algae. Tip: place your garden furniture where the most light and sun fall in your garden.

So, green algae is actually a collective term for algae and mosses. Algae and mosses cannot exist without each other. The algae feed the mosses, and the mosses protect the algae. They live in a sort of symbiosis.

Removing green algae

But what should you do if your garden furniture is already covered in green algae? Then there are a few inexpensive remedies that work very well with surprisingly good results. The first is cleaning vinegar or natural vinegar. Cleaning vinegar is produced synthetically and much stronger than natural vinegar. For more delicate materials such as natural stone, we recommend natural vinegar. With vinegar, you can easily remove green algae from both patio tiles, garden furniture, lounge sofas, and teak garden benches. Why does green algae tolerate vinegar so poorly? This is because the acids in the vinegar are fatal to algae and mosses.

Another inexpensive and highly effective remedy is soda and soft soap*. Mix 2 cups of soda and 2 cups of soft soap in a bucket of warm water. Then scrub the solution onto the patio with a stiff brush. Allow it to work for a little over a quarter of an hour, then rinse off with a garden hose. This method can also be applied with a brush or a coarse sponge for garden furniture and protective covers. An added benefit: soft soap is 99% biodegradable, making it an environmentally friendly cleaning agent.

*Soft soap is often also named green soap

Another good option is a special green algae cleaner, such as the one from HG, which may be a bit more expensive but highly effective. This algae cleaner should be applied in dry weather for the best results. This way, the algae and mosses will absorb the solution maximally. If it remains dry for a few more days afterward, the effect will be optimal. For large surfaces like patios and decks, applying with a watering can or bucket with a broom is effective. For garden and lounge sets, it's easier to use a plant sprayer or a pressure sprayer. This method works very well for teak lounge furniture. You simply mist the solution over the teak furniture, ensuring it reaches all the gaps and corners. This latter method is also commonly used to clean protective covers that have turned green. One advantage of green protective covers is that the furniture underneath remains clean.

Do not use a pressure washer. As garden furniture specialists, we've seen many lounge and garden furniture pieces heavily damaged by the use of these devices.

But what if there is green algae on my garden cushions? How do I remove green algae from my lounge cushions?

If you have Sunbrella lounge cushions, you're in luck because these superb cushions can be cleaned with bleach. Make a solution with some bleach and mild soap in a bucket. Let it soak for about fifteen minutes, then clean with a soft brush or a coarse sponge. Be sure to rinse thoroughly for the best results.

For regular garden cushions, it's a bit trickier and requires a bit more effort. Cushions made of Acrylic or Dralon are easiest to clean with a brush or sponge, water, and a mild soap or all-purpose cleaner. First, scrub with the sponge or brush and let it sit for 15 minutes. Then rinse thoroughly with plenty of water.

But of course, the best approach is to prevent the lounge cushions from turning green in the first place. This can easily be done by storing your cushions in one of Biohort's storage boxes. If you don't have space for this, you can store your lounge cushions in one of our cushion bags.

How to prevent green algae

Perhaps it's much easier to prevent green algae. Green algae is always caused by organic debris. This includes leaves, twigs, seeds, pollen, dust, insects, and anything else floating, flying, blowing, and crawling through your garden. Subsequently, this settles on your patio, garden furniture, cushions, and protective covers. On this fertile ground, green algae thrives. By sweeping your patio thoroughly a few times a year, you can address the main cause of your problem. If you do this in combination with joint sand, the result is even better. Keeping the joints clean by weeding and hoeing out weeds also reduces algae growth. For the lazier gardener, pouring boiling water over the joints is also a solution to keep them clean.

Another simple solution against green algae is to ensure that water does not remain on the patio. Having good drainage makes a big difference. Check if the drainage is working well and not clogged, and remove twigs and leaves from the drainage.

Let sunlight into your garden. Over time, trees and shrubs may grow unnoticed. A good pruning session provides more light and sun. Sunlight and algae do not tolerate each other well.

Green algae cleaners from brands like HG also have a preventive effect because the solution penetrates the material. This slows down the growth of new algae. This applies to both the patio tiles and decking planks, as well as the protective covers.

The easiest way to keep your garden and lounge furniture free from green algae is to purchase a good protective cover.

​​For more information on how to prepare your lounge set for winter, be sure to read our blog on getting your lounge set winter-ready.