What is Red Mulch?
Many gardeners use mulch to protect their plants and promote growth. Mulch is essentially any material that is used as a protective layer over the soil, insulating it from the harsher effects of climate and erosion and helping to retain soil moisture, among other things.
Red mulch is any mulch which is painted red. Red light is the wavelength most readily absorbed by plant leaves, which themselves reflect green light (hence why most plants are a shade of green). Reflecting red light that hits the Earth back up to plant leaves can promote growth, with some manufacturers claiming a 15-20% improvement.
Red mulch is generally either made from red plastic sheeting or wood chippings that have been painted red. Recycled red mulch can be manufactured from old tyres or other plastic materials and can easily be made at home.
How to Make Recycled Rubber Mulch
To make recycled red rubber mulch, first obtain some old scrap tires. These can bicycle tires, car tires, or any other kind of tire. If they are car tires, however, they will need to be pried away from their steel casing with a pair of pliers before you can proceed, as all that is required is the rubber.
Now shred the tires, either using a sharp knife or a shredder. The resulting pieces should be around 1 square inch in size. Once done, lay the pieces out over newspaper and paint them red. Spray paint is often used though eco-friendly paints, which can also be made at home, are much kinder to the environment. Once the paint is dry the pieces are ready to be laid in the garden as mulch.
An alternative to rubber mulch is to make it from wood chips. The process is much the same but instead of shredding old tires old wood is used. This wood can come from any source and can simply consist of dead tree limbs and sticks.
Environmental Pros and Cons of Recycled Red Mulch
Mulch comes in many different forms and most types of mulch can help to promote growth and ward off pests, simply by virtue of the environmental protection they offer. Red mulch can be particularly effective at producing larger plants, particularly strawberries and tomatoes, while red rubber mulch can provide more effective insulation than some other forms while also allowing moisture to reach the soil uninhibited.
However, some red mulches have also been reported to damage plants. This has given rise to the rumour that red mulch is toxic and should not be used. Red mulch itself is not toxic – that is, the toxicity has nothing to do with the red paint – but some of the materials which can be used to make it potentially are.
Some wood purchased from construction and demolition sites, for example, has been treated from chromated copper arsenate and has been shown to contain arsenic. Mulch made from wood treated with chromate copper arsenate is potentially poisonous. Rainfall could cause leaching of the arsenic into the soil, either killing plants or causing toxic build up of arsenic in fruit and vegetables that are then passed on to animals and humans.
Similarly, processed rubber from tires may contain cadmium, chromium, aluminium, copper, iron, manganese, molybdenum, selenium, sulphur and zinc. Zinc is often found in particularly high concentrations and this too can leach and potentially damage affected plants and soil. Scientific research is still inconclusive as to whether mulch made from rubber tires is dangerous, but many gardeners have reported problems when using it.
Eco-Friendly Recycled Red Mulch
Recycled red mulch can be environmentally friendly as long as the right materials are used to create it. Used wood directly from fallen tree bows, for example, and painting them with natural paint is probably the most eco-friendly way of producing red mulch. This uses natural products and doesn’t run the risk of potentially dangerous substances leaching into the soil. The key is to be careful about where materials are sourced from.
Red mulch is popular with gardeners and using recycled materials to produce can be an eco-friendly way of manufacturing it. It is relatively easy to produce and can be made from old tires or wood. Natural materials that have not been processed are always the best things to use however; when recycling processed materials it may appear that you are doing the environment a favour but in fact you may be exposing the soil to toxic substances.
Garden Guides, “How to Make Recycled Rubber Mulch”, https://www.gardenguides.com/88825-make-recycled-rubber-mulch.html
Garden Guides, “Benefits of Red Mulch” https://www.gardenguides.com/77213-benefits-red-mulch.html
Mulch and Soil Council, “Policy Statement on CCA-Treated Wood in Horticultural Mulches”, https://www.mulchandsoilcouncil.org/Inforesorce/Industry/Announcements.html
Nature’s Way “Rubber Mulch – Beware”, https://www.natureswayresources.com/DocsPdfs/RubberMulch.pdf