On average, hair grows about half an inch per month, but the exact amount varies and is affected by everything from genetics and ethnicity to stress levels, medication and general health. There are three phases of growth and shedding: anagen, catagen and telogen. The anagen phase is the most active of the three and is when new cells are formed in the root of the hair. To optimize growth in this key stage, it’s important to keep hair healthy, because breakages may be one of the reasons it isn’t growing as long as you would like.

“Healthy hair will not break as easily as dry, brittle hair, and therefore will reach its natural maximum length,” says trichologist Candy Lewis Williams, ND. So, how can you tell if your hair is in shape? “Healthy hair will have its own natural shine, without styling products.”

For most of us, while the hair closest to our roots might feel full and healthy, our mid lengths and ends tell a different story. “The degree of thinning and breakage shows how unhealthy that once-fresh root hair has become following exposure to things like chemical treatments and heat styling. Healthy hair grows longer more quickly because it’s not thinning, breaking and shrinking at the ends,” says hairstylist and founder of the 3 More Inches range Michael Van Clarke. “Well-cared-for hair can retain 90% of its thickness and shine at 18 inches long. But poorly-cared-for hair can easily lose 98% of its mass at the same length, through thinning, breakage and split ends.” Using the right shampoo and conditioner for your hair type, plus doing regular intensive treatments and masks, can make all the difference. If you have Afro or textured hair, your main concern should be keeping dryness at bay, which can restrict growth. Look to keep your hair well moisturized with deep conditioners and oils, such as jojoba and argan oil, which help promote growth.

The scalp is often overlooked when it comes to haircare, but it is an extension of your skin, so be diligent with thorough cleansing, regular exfoliation and proper nourishment. If neglected, poor scalp health will not only slow hair growth but can actually lead to hair loss from bacterial and fungal infections. To keep both your hair and scalp healthy, aim to shampoo every other day, unless you’re working out a lot or your hair is subjected to heavy pollutants or dust – in which case, do it more frequently. Failure to remove a build-up of dirt and grime can mean an itchy, irritated scalp, which will have a knock-on effect with the health of your hair and, ultimately, impact how long you can grow it.

Protein-rich products help to keep your hair in shape. Look for those containing keratin or amino acids, as they help nourish, repair and replace any protein that’s been lost through damage. To protect your strands, avoid silicones and heavy oils, says Van Clarke: “Despite making the hair look lovely today, they dehydrate the hair and ruin it for tomorrow.” And try to steer clear of sodium laurel sulphates (SLS) and DEA, says Williams, which act like detergents, irritating your hair follicles. As for heat, avoid regular heat styling, but if you must iron or blow out your hair, set your tool to a lower temperature and always apply a heat-protection spray first to minimize damage. Never, ever iron wet, damp or even dirty hair, because adding intense heat to hair with a build-up of dirt and product will compact the damage and lead to breakage. Getting regular trims may seem counterintuitive if you’re trying to grow your length, but banishing split ends is a must if you want long-term health, says Williams. “I recommend a trim every eight weeks; a split end can catch in your comb or brush, and it doesn’t always break on the ends – it can break off three or four inches up the hair shaft.”

Hair growth is considered non-essential compared with other bodily functions, so it’s low down on the priority list when it comes to getting nutrients. If you’re restrictive in your eating, hair growth can be halted altogether, and you may even experience shedding. Make sure you eat a rounded diet that features plenty of complex carbohydrates and protein to boost energy to the follicles and encourage growth. “Hair is 3% water and 97% protein, so a diet without enough protein will impact hair quickly,” says Van Clarke. Aim to eat at least 50g of protein each day, such as chicken, fish or eggs. Certain vitamins, minerals and fatty acids are also essential: broccoli, oranges and kiwis contain high levels of vitamin C; leafy greens are rich in vitamin D; and almonds and avocado are high in vitamin E. You’ll need plenty of iron, omegas 3 and 6, and biotin to promote healthy follicle function, too, while zinc and vitamin B12 are also key because they help produce new hair cells.