Known as ‘the meadow maker’ or ‘nature’s lawnmower’, yellow rattle is the single most important plant you need to establish when creating a wildflower meadow.
Without it, vigorous grasses grow unchecked and smother the flowers you want to encourage.
Yellow rattle (Rhinanthus minor) is an annual, completing its life cycle in one year. In early spring the seeds germinate and grow quickly. As their roots develop underground they seek out the roots of plants growing nearby, especially grasses. Once contact is made the yellow rattle draws water and nutrients from them, suppressing the growth of grasses by as much as 60%. In the resulting space, other flowers have room to grow.
The flowers of yellow rattle are pollinated by large bees (especially bumblebees) and are followed by large, inflated seed pods. When these ripen and dry, the seed inside rattles around; in former times, farmers used this sound as their cue to cut the hay.
Top tips to establishing yellow rattle
Yellow rattle can be a little tricky to get established, but the tips below should help you get it going. The five golden rules to bear in mind, are highlighted in bold italics.
How to: source the seed
Yellow rattle seeds are very short lived (1 year to 18 months) and must be sown as fresh as possible. You can buy seed but make sure it comes from a specialist supplier who can guarantee it was harvested within the last 12 months. Even better, if you know someone that has yellow rattle in their meadow (maybe a local nature reserve or farmers’ field) ask if you can collect some seed. Collect seed from June to August by picking a few stems on a dry day and shaking them into a paper bag. Allow a small handful of seed per square metre, but remember you only need a few plants to grow in the first year – they’ll produce much more seed for you in following years.
How to: sow the seed
Cut your grass as short as you can between July and September and remove the hay or clippings. Then remove the thatch (the layer of dead grass and moss that builds up on the soil surface) to expose some bare soil, using a rake or harrow. This ‘scarification’ is really important; the seed must to be able to reach the soil surface. Aim for at least 50% bare soil, preferably more. Sow by hand straight away, scattering the seeds on the soil surface. This must be done by November as the seeds need about 4 months of temperatures dipping below 5oC in order to germinate in spring. Seed sown after Christmas germinates poorly. If you’re sowing an entirely new meadow in an area of specially prepared bare soil, sow the yellow rattle along with all the other seeds in the autumn.
How to: keep yellow rattle going
Seedlings will begin to appear in spring, from late March through to May. Don’t be worried if only a few plants germinate in the first year. They’ll grow and shed their own seed and numbers should increase rapidly. From now on you don’t need to scarify the soil each year, just cut the meadow really hard once the seed has been shed and remove the hay or clippings. This can be any time from late July or preferably into August or early September, allowing late-blooming plants to provide food for pollinators and shed their seed. Aim to get the grass sward below ankle height. In agricultural settings, grazing the meadow hard now with cattle or sheep until New Year (if it’s not too wet) is very beneficial. In a garden setting, cut the grass (and remove clippings) once or twice again before Christmas. If your soil is very fertile you might struggle to keep yellow rattle going – it can slowly disappear. Always create meadows on poor, infertile soils.
Part of the joy of creating a wildflower meadow is seeing the gradual changes over time. As yellow rattle establishes, the grass will become thinner and plants like oxeye daisy, knapweeds and vetches will start to appear. Eventually, if you’re lucky, even a few orchids might find a home.
It’s a long journey, but it starts with yellow rattle.
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