The RHS recommends the use of containers that give herbs a deep root course in which they can remain undisturbed.
The website says, “Use a gritty, well-drained compost that will add up to 25 volume percent coarse grain or perlite to a clay-based compost like John Innes # 1.
“Keep the compost moist, but never moist. Use a balanced fertilizer to encourage leaf growth rather than a high-potassium fertilizer that might encourage flowering.
“Mint enjoys moist, fertile soil, but it’s not the happiest herb in a pot. Often transplant with generous pieces of root in rich potting soil, making sure not to overpot. If it looks messy, lift up the roots and dab it in fresh compost.
