She's lovin' it: How a trip to a McDonald's Drive-Thru led to an unlikely love of super-size grasses

The McDonald's Drive-Thru Garden: how does that sound? I've been doing some automobile-based garden visiting. Not quite visiting, I suppose, if you don't actually get out of the car. But a McDonald's Drive-Thru is, I think, pretty much predicated upon the idea of you not getting out of the car. It also possesses a totally surprising and rather nicely planted little garden, deftly placed between the order microphone and the paying window. Pieces of broken black slate on the ground, red-leaved cordyline, a deeply lobed black-leaved elder that throws up raspberry tones in bright sunlight and, this time of year, pale wheaty festuca grasses.

The beauty of the grasses (as you turn the corner trying to make sure you have the right change for a Happy Meal) is a neat reminder of the loveliness of the whole grassy tribe this time of year. Grasses come into their own in September. They spend the summer looking faintly alluring, with their thin, long blades pouring from the centre, a minimalist idea for how a plant should look. But come late summer, they produce their flowers, rich with the sense of harvest. Because these flowers, followed by seedheads, are fairly simple in construction and often pale in colour, so the whole plant continues to look good until well into the early winter. This can give you up to six months of elegance for a single plant spend – good value in the costly world of horticulture.

So what's the catch? The first thing you need to know about grasses is that they are mostly going to need both room and sunshine. These are often prairie plants, removed from wide-open grasslands and expected to flourish in suburban Britain. So they are the perfect candidates for the kind of garden (like those at McDonald's) where the plants are never going to be exactly touching. Kept apart by stone mulch, each grass gets to show off its own individual silhouette.

Stipa tenuissima (£8.99, crocus.co.uk) is an energising grass for such a sunny flowerbed, with flowers that appear earlier in the summer but which will last until autumn, moving in the slightest bit of wind. By then, every part of the plant will be bleached to a ripe-corn colour, forming a strong element in any design.

Pennisetum alopecuroides "Hameln" (£7.99, Crocus) is also a perfect choice, with fantastic seedheads that hold their place daintily, and a grand shape.

Or for something more unusual, try the recently introduced Molina "Poul Petersen" (£8.99, Crocus), named after Denmark's most celebrated grass expert. This holds a good shape, with enticing, touchable violet flowers at the end of long stems.

Another totally dramatic purchase is Panicum virgatum "Heavy Metal" (£9.99, Crocus). Some leaves will be almost as tall as their gardener, and this grass provides a strong vertical impact to borders where you need to lift the eye up and away.

But what if you lack perfect grass-growing conditions? A few grasses have slightly less demanding notions in life. Lack of space? Try Miscanthus sinensis "Morning Light" (£8.99, Crocus), a tightly growing cultivar with a small footprint. Each stem has several elegant green-and-white leaves, and the whole effect of adding one is a touch of stripey class.

Or perhaps your garden is a bit damp for grasses in general. Then you could order in the unpoetically named Deschampsia cespitosa (£7.99, Crocus – it's the cess-pit bit that worries me). This is the grass that McDonald's has chosen for its slightly shaded slate garden, and it's a good one, flowering from June onwards and retaining perfect seedheads into October.

And finally, what if, having scrutinised the availability, you fear you are about to break the bank? Well, Mr Fothergill's does a "Grasses Collection" from seed, allowing you to try six stylish favourites from a single £4.55 packet (mr-fothergills.co.uk), including a bronzey Carex, the strokeable foxtails of Setaria macrocheata, the hovering insect hum of Agrostis nebulosa and the frondy holidayness of Melica ciliata. What better way to start your own grass garden than by growing your own? Just make sure to label the whole tray very, very carefully. It turns out that when it comes to germinating baby grasses, they can all look extremely similar…