Starting a wildflower meadow?
It's that time of year when you need to sow Yellow Rattle, Rhinanthus minor. Yellow Rattle, or Hay Rattle, or Cockscomb, is an attractive yellow annual wildflower of meadows. It’s a good bumblebee and butterfly plant and flowers in June before setting seed, which rattles in the wind, traditionally telling farmers it was the time to make hay.
Yellow Rattle gets some of its nutrients from surrounding plants, particularly grasses. As a hemi-parasite it was regarded as a pest by farmers, as it could reduce hay yields by up to 50%. It doesn’t make the grass look sick, but just enfeebles it. This provides obvious benefits if you’re trying to establish a wildflower meadow, particularly in an existing sward or on a site with reasonable soil fertility. In either case, without some kind of regulating mechanism like Rattle you will most likely end up with no wildflowers and lots of grass.
Establishment
Rattle seed needs to go through a prolonged period of cold before it will germinate, so must be sown from autumn up to Christmas. It has a limited shelf life, so seed from the current harvest is best sown this year. This trait in an annual means that it’s very easy to get rid of it; just mow in May/June before it sets seed. If you sow a general meadow mix which includes Rattle in spring it’s worth buying extra in the autumn to add to it.
We recommend a sowing rate for Yellow Rattle of between 0.5 and 1g per square metre, and will sell you seed down to 100g. As it parasitizes grass it must be sown with grass seed or into an existing sward; don’t try to get it established in a seed tray. After sowing, lightly roll or tread the seed in to ensure good contact with the soil. Yellow Rattle seeds are light and wind born, so this is particularly important.
It's important that you scarify or chain harrow any existing grass, and then cut as short as possible before sowing the Rattle. Keep it grazed or cut to below 2cm throughout the winter after sowing and throughout winters thereafter. The seedlings start growing in early spring, so make sure you don’t chop their heads off! Add plug plants or seed to the site in the second year, following a similar routine. Alternatively, you could cut strips or squares out of the Rattle affected grass, replace the soil with a sand/topsoil mix or subsoil, and sow your wildflower seed or plant your plugs in these areas.
It’s really important to keep you meadow area cut short from late summer to spring for Yellow Rattle to self seed successfully.
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