Yellow rattle: the meadow-maker's helper

I have just rattled off a stiffly-worded email of complaint, for it has just dawned on me that it is now over a month since my lawnmower went in for repairs at the local garden machinery workshop.

I have started converting a number of areas of lawn in my garden to flower-rich meadows, and my mower simply isn't designed for such work. I have let the meadow plants grow, flower and seed, and the resulting foot-high herbage is overpowering my machine. Wild flower meadow creation is not proving to be the walk in the park as described by the magazines.

Problems aside, the developing grasslands have given me a great deal of pleasure. In an earlier posting I have mentioned the flourishing bee orchids that occur naturally in the lawns here, but more exciting still has been the appearance of a single flowering early purple orchid in a spot in which I scattered seed roughly four years ago. Another native beauty present is the greater burnet saxifrage (Pimpinella major), something of a local speciality here to the east of Plymouth, and notable for its airy stems of queen anne's lace flowers that are so flawlessly white they gleam in the dark. And, of course, these flowers have attracted a wealth of insects: brown and blue butterflies in abundance, and bees galore.

But one thing has outshone everything else, and that has been the yellow rattle (Rhinanthus minor). I love this plant for its strongly architectural structure and its burnished golden flowers, which look like tiny turtles hatching from their eggs. The plant has a more practical use, too, for it is a "hemi-parasite" - a partial parasite - and can be used to reduce the vigour of meadow grasses. Sure, it produces green leaves that photosynthesize, generating energy for plant growth from the sun's ray, but the rattle is happiest when its roots lock onto those of the grasses and suck the life out of them. Even out of flower, areas of meadow heavily invaded by this species support only the most meagre growth of grass: little wonder yellow rattle is loathed by farmers.

It is loved, however, by those keen to establish a meadow grassland rich in flowers. It's important to reduce competition from coarse growing perennials, grasses included. This can be done by stripping nutrients from the soil – for example, by scraping off the overlying topsoil to reveal the poorer subsoil beneath – but yellow rattle achieves much the same results at considerably less cost and effort, and has become a mainstay within wild flower seed mixtures.

If you want to introduce this species into your lawn, it's worth understanding the plant's ecology in the wild. It is an annual species that germinates in spring (typically March), flowers at the height of summer, and is in full seed a couple of months later (say, late August). As a strictly upright plant it cannot tolerate being cut or grazed off too severely during this period, so is most at home in old-fashioned hay meadows, where grazing is excluded during the summer months, and a late hay cut allows a good proportion of flowers to have successfully set seed.

First cut your area of grass - think more of shaving a head to control nits, rather than a short back and sides – and collect and dispose of the clippings elsewhere. Sprinkle seeds very thinly over the scuffed turf: even a seed or two per metre is ample, for if the introduction is successful, the resulting plants will shower the ground with an abundance of fresh propagules within the year. The seed is apparently short-lived, so sow it fresh in the late summer or autumn, and no later. You can cut as short and as often as you like through the winter and into spring, but by March, stop cutting, or at least raise the mower blades, for the seed should be germinating by then. You can probably get away with a final cut into early summer if you set the mower blades at their highest setting, for the youngsters will simply be encouraged to form a strong bushy plant if decapitated in their first month of growth.

However, by mid May all mowing should cease, to allow the rattles to flower and seed. You'll know that the plant is mature and shedding ripe seed when the fruits take on a ghostly silvery-grey colour, and rattle when shaken: at this stage it looks rather like a poor man's honesty.

Don't be too hasty to cut and remove the rattle-rich hay for the fruit ripens over a period of weeks, but when most of the seed heads have turned grey, it is a good time to pull up bunches of the plants, and to shake them over new lawn to encourage the large disc-shaped seeds to fall. With the last seed successfully shed, it's time to start that heavy mowing again. Which is, of course, why my mower is now struggling! Next year, I am going do my big end-of-year cut with a strimmer, and then rake and collect the cuttings by hand, before bringing out the mower.

Yellow rattle seed is widely available to buy, but do check with the supplier that the seed is of local provenance. Six loosely defined subspecies of yellow rattle occur across Britain, reflecting differing geologies and habitats, so it would be tragic if we upset this balance through the introduction of non-native stock from the continent. Better still, you won't do any harm by taking just the smallest handful of seed from a natural population growing in a meadow close to your home, and use this to start your garden colony. Do make sure that you are removing only the tiniest proportion of seed from the wild colony, and check that the landowner is happy.

Andy Byfield is one of the founders of the wild plant charity Plantlife.