Homeowners plagued by unsightly black spots on their patios can now banish them with a simple citric acid solution, according to an expert. Black spots are caused by lichen, which thrives on stone surfaces in damp, shady conditions common across the UK. Unlike moss or dirt, these marks can be stubborn and time-consuming to remove.
Tom Allen, owner of TGA Concrete Pumping, recommends using citric acid — a cheap household item. A 250g box costs just £2.25 at B&Q, or £10.90 in bulk on Amazon. For those who find citric acid ineffective, a patio cleaner from Wickes is available for £14.
To make the solution, mix one cup of citric acid powder with one gallon of warm water until dissolved. Apply generously with a watering can or spray bottle to the affected areas. Let it sit for 15 to 20 minutes to break down the lichen, then scrub vigorously with a stiff-bristled brush or broom before rinsing with a garden hose.
Allen explains that citric acid, found naturally in lemons and oranges, has powerful cleaning properties that effectively tackle these stains. This method offers a quick and affordable alternative to harsher chemicals or pressure washing.
