Yellow Rattle (Rhinanthus minor) Seed
Yellow rattle (Rhinanthus minor) is an attractive, partly parasitic ("hemi-parasitic"), annual wildflower of short grasslands. "Partly", because it photosynthesises. It's part of the Figwort family, and used to be widespread across the UK on mostly neutral soils. Although it's still found across the country, including in the Machair, it's now much less common. It's appearance is variable; we think there are at least 6 sub-species of it in the UK.
Once Yellow rattle is established it can reduce the vigour of many grasses by up to 50%, thus benefiting other sown wildflowers - check out our blog on how to grow and manage it. Once it dies back, each Rhinanthus plant leaves a space for wildflowers to fill too. It does need full sun, however, and even Yellow rattle will be shaded out by more vigorous grasses on fertile soil - it's not the key to all a meadow maker's problems. Having said that, it can work brilliantly in helping to bring wildflowers back into old pasture, although of course it doesn't of itself reduce soil fertility. Yellow rattle also has other unexpected results. For example, ribwort plantain has learnt to retreat away from it, so does tremendously well in swards with a lot of Rhinanthus in as it fills in the space it leaves behind. Clever things, plants.
Rhinanthus is a helpful plant for pollinators too, particularly bumblebees and butterflies, although honeybees find its slightly complicated flowers difficult to access..
For obvious reasons farmers were never terribly keen on Yellow rattle, although it's apparently tasty for livestock. That said, as it is an annual it's easy to mow out before it sets seed (when it rattles) in July. This was traditionally time to cut the hay; hence its synonym, "Hay Rattle". Its seed has notoriously short viability - you must sow from this season's harvest. It will also disappear in thick, unmanaged sward. The seeds are small and the plants unable to compete with surrounding vegetation early on. Nowadays, silage cuts over the summer stop it from seeding at all. Needless to say, it's much less common than it used to be a hundred years ago.
Yellow rattle seeds are light flat discs, designed to be wind blown. They germinate from January and the seedlings become evident in early March, so that they steal a march on the surrounding grasses. Be careful not to mow them out! Once they've got going they are easy to spot, however. The leaves have serrated edges, a bit like a nettle, and in seedlings look rather stiff. The flowers look a little like yellow snapdragons (or little cockscombs, apparently). They're very pretty. The plants grow to around 50cm tops.
Yellow rattle seed must be sown from summer to the year end, as it needs to be chilled to trigger its germination the following spring. We recommend adding the seed to a newly established meadow after its first season. As it doesn't last the seeds need to be as fresh as possible. It also reacts badly to being badly handled - it's tricky to process properly. You need to be careful where you source it from. Our Rhinanthus seed is freshly harvested from meadows around southern England. We test it once it has been harvested and cleaned to check on the seeds' viability. Seed from the 2021 harvest returned germination results of 80-85%.
The time to seed Yellow rattle is between harvest and the end of December. Like some other of our wildflower species, it needs to get cold to trigger germination - "vernalization". Sow by hand onto existing sward, at a rate of up to 1g per square metre. It's expensive stuff, so you might want to use a lower rate or just seed some areas and wait for it to spread. It's really important that the existing grass is cut VERY short before seeding and, if necessary, chain harrowed or scarified to get rid of any thatch. Ideally you should see 50% earth. The seeding rate is very low, so you might want to add sand or similar to bulk it out. Once sown, either walk or lightly roll in, or use livestock to tread in the seed and make sure it's in good contact with the earth.
Yellow rattle is a plant of short grassland - if the grasses surrounding it are allowed to grow long and rank it won't be able to compete. Once you've taken a hay cut, typically from July to late August, it's important to keep the grass lightly grazed or cut (removing cuttings) over the winter. Stop cutting in March, or you'll chop the heads off the young seedlings!
Our Seed For Sale
Yellow rattle seed may be ordered in 0.1 kg increments from 0.2 kg upwards. We sell smaller quantities at our sister website: BritishWildflowerMeadowSeeds.co.uk.
The seed we sell is always from the current harvest, and is carefully stored and processed to avoid damage and low germination. We also test it. We typically deliver from July to December.
The Yellow Rattle seed for sale here is taken from sites across southern England and Northumberland. We sell each separately. The Northumberland seed is taken from an elevated and exposed site with neutral soil. We also sell smaller quantities of Welsh seed (from Pembrokeshire) via British Wildflower Seeds.
We strongly recommend reading up on meadows before buying Yellow Rattle seed. Although our Rhinanthus seed has high germination rates, you need to be careful about initial care and establishing an annual regime. Don't be put off though - once you get the hang of it it's pretty straightforward, so long as you follow instructions!