Penstemon

Penstemon is one of those plants that keeps the garden going long after most things have given up for the year. 'Garnet' is my favourite — those deep, wine-red tubular flowers that keep appearing on upright stems from July all the way through to the first serious frosts in November. That's five months of colour from a single plant, which is an extraordinary return.

The colour is rich and saturated — a true deep garnet that glows in the low autumn light. Each flower is a neat little tube that opens into a two-lipped face, and they're arranged in loose spikes that have a natural, unforced elegance. Bumblebees love them — they're exactly the right shape for a bee to climb inside, and on warm autumn afternoons you can hear them humming their way up each spike.

I grow a whole row of them along the edge of a border, and by October they're the main event — everything around them has retired for the year, and there's 'Garnet,' still producing fresh flowers like it hasn't noticed the season changing.

They're not fully hardy everywhere — a hard winter can kill them — so I take cuttings in September as insurance. It's a five-minute job and the cuttings root ridiculously easily in a glass of water on the windowsill. A small investment for a plant that gives you colour when you need it most.