Lemon verbena (aloysia citrodora) has a refreshing citrus scent that has a variety of culinary uses both sweet and savoury. Its flavour is very strong and cuts through sharply, so use it with care. I’ve used it to flavour sorbets and syrups and it works very well with blackcurrants.
It also makes a really nice tea that has a clean fresh taste, good after a heavy meal or to help settle an upset stomach. You can buy it dried and it’s popular in France and Morocco where it’s known as vervaine but I love it fresh from the plant.
It’s frost tender so grow it in a pot and bring it indoors over the winter. Even in an unheated greenhouse it will die down completely and look pretty dead, but it will spring back to life as the weather warms up.