Yellow Rattle Seed

Growing and Caring for your Yellow Rattle - Rhinanthus Minor

 This article aims to help you successfully grow Yellow Rattle.

 Background

This pretty yellow flower is found in traditional hay meadows throughout Northern Europe. It can be difficult to grow, but when the conditions are right it will spread rapidly. Its spread outside the meadow is mainly by mechanical means by being caught on machinery or in a crop, such as hay, that has been harvested in July. Some of the seeds are, therefore, still encapsulated in the plant. Naturally, it does not spread far from its parent plant. Turning the hay helps spread this further in the process of haymaking. It does not like rough ground when germinating and is therefore confined to the meadows where the grasses are cut or grazed. The plant is a sought-after species for conservationists, who try to encourage colonisation and promote biodiversity. Its preferred habitat is dry fields or meadows. It does not tolerate any shade, as this delays germination. The sun is low in March, so even a low hedge can cast a lot of shade. Its flowering period is between May and July, being at its peak in late June,

   The seed germinates on the surface of the soil in February or March. At this time of year, the seed will have been resting for 6 months and would have stratified due to chilling between 2 and 8 degrees Celsius. With the right conditions and a few warm days, the seed germinates and, depending on your latitude and local weather conditions, it throws up a small, two-leafed shoot that looks a bit like jagged-edged stinging nettles. The energy in the seed is soon used up, and if the grass is too long, it won't be able to take any energy from the sun and will soon perish. This is the main reason why this seed is difficult to grow. If established successfully, its roots will parasitise onto a grass, or clover, nearby in April/May. Without Grass, the yellow rattle will struggle to thrive and eventually perish. This delicate balance between having grass but not too long is critical for the survival of Yellow Rattle.

By late May, the plant should have begun to flower. This is orange/red at the base as it opens, turning to yellow in full bloom. The leaves are small, as they take part of the nutrients from the grass and clovers. Flowering continues for 4 weeks, and by early July, the seed pods have ripened to a golden colour and can be heard rattling in the breeze. If there is sufficient Yellow Rattle, the grass would hardly have grown and, by the end of June, be relatively short and easy to cut. A lot of Yellow Rattle is not good for livestock, so it is best to allow the rattle to set seeds thoroughly before cutting them for hay. The plant will dry and crumble with little trace left in the hay. Once the Yellow Rattle has died off in mid-July, the grass can grow on freely, rain permitting.

 Other common names - Cock's Comb, Hay Rattle, Shackle Bags.

Food plant of the caterpillars of the Grass Rivulet Moth and a favourite nectar source of the Bumble Bee.

See Wikipedia for a good description.

 

Sowing Yellow Rattle seed

Yellow Rattle, or Rhinanthus minor, is a fascinating plant that plays a crucial role in managing meadow ecosystems. An annual hemiparasite requires careful timing and specific conditions to thrive, making procuring fresh seeds from a reliable supplier essential. The unique germination process of Yellow Rattle, which depends on early warming by the sun, moisture, and light rather than soil warmth, allows it to establish itself before perennial grasses can dominate. This early start is critical for Yellow Rattle to parasitise the roots of these grasses, thereby reducing their vigour and allowing a more diverse range of meadow flowers to flourish. Sowing in autumn, immediately after harvest, ensures that the seeds are in place to take advantage of the optimal conditions for germination. Consistent management, including the correct sowing density and maintaining short grass in the spring, is key to the successful establishment and persistence of Yellow Rattle in a meadow setting. This management supports the growth of Yellow Rattle and contributes to the meadow habitat's overall biodiversity and health.
 
Yellow Rattle and mixtures with it must be sown before December of harvest. (However, grass that has been cut is sacrificed to the soil; this can be extended up to early February).  Broadcast the seed into recently mown (or sowed) grass. Divide the plot and packet into equal areas and quantities. To ensure even distribution, sow each subplot separately, avoiding windy days when the seed can be blown off course. Do not cover the seeds. Scarify, roll, and graze the regrowth with sheep or cattle. The animals or machinery will remove the grass and help to tread the seeds into the ground. Ideally, grass should be short in January, and every January, it may need mowing again. If only a tiny area is sown on a large field, choose a line across the field, as the seed will tend to spread in the following years.
 

Growing

The seed needs to vernalise to break its dormancy. That is, it needs to be exposed to cold weather for 60 to 90 days. It is important that the seed is sown on the surface and not covered in good time to be exposed to cold weather. This will also allow the seed to wash in and have good contact with the soil. 

Germination begins between February and April in southern England and later in shady areas or further North. It is so good at germinating that it is partly its downfall. Most of the seeds will germinate, but only a few will survive for one of the following reasons:

1. Because they cannot find a host grass
2. The grass is too long or shaded, hence delaying germination
3. Dry weather

It is advisable to keep stock off these fields from February till August. Allow the Yellow Rattle flowers to ripen and the seeds to blow out. Some of the seeds will be held in a pod, so it is advisable to thrash these out before cutting, especially if you are using a mower with a collector.

 Cutting:  In any event, leave cutting as long as possible. September or October is ideal. Yellow Rattle stops grass growing between May and July. Leaving the cutting later can be more difficult, but the results will be rewarding.

Beware - Yellow Rattle is an annual species. It will die out in a year if the plants are not allowed to set seed or the grass is too long at the beginning of the year.

 

Grazing

We have lots of Yellow Rattle in our fields and make and sell lots of hay for horses with no problem. It is all made after the Yellow Rattle has gone to seed, and the plants are brittle, crumbling, and falling out of the hay. Some may remain, especially the stalks, so there seems to be no problem with feeding it dry. We have not seen any evidence that it is poisonous to livestock when green and our sheep graze in the fields from March to April when it is at its most palatable. It does not have many leaves when it is mature, so again, it is not very palatable. As with everything, if there is nothing else for the livestock to eat, too much Yellow Rattle could be bad. However, it has always been in traditional hay meadows and is often made into hay in June without any problems.
 

Weeding

In Spring, go around your wildflower meadows and hoe out any Spear Thistles with a mattock at the rosette stage.
In late June, dig up any Docks and Ragwort. Put it straight into a large bag or wheelbarrow to contain any seed that may fall off. Use a fork to dislodge/loosen the root, or turn the sod over and extract the entire root.
Creeping Thistles need to be pulled in Late June. They are easy to pull as long as you don't try to pull any grass simultaneously, but you will need a good pair of gloves for this one. Put it straight into a bag. You may need to repeat them as they share a common root system. If persistent and thick, cut in early June. You can also use a selective herbicide, such as Grazeon.
Keep an eye on Himalayan Balsam, as it is starting to become invasive in many places. I suggest keeping it under control before it spreads.
Burn all these species and not put them on the compost heap.

Bracken control: Cut it when it is young. If it is a big problem, try compacting the soil by feeding cows or horses in these areas when it is wet, especially in May, before it appears.

When using herbicides, please ensure you have the appropriate training or use a contractor.

 

Controlling Yellow Rattle

Some people have asked how to manage Yellow Rattle in their meadows if it gets too dominant. It is relatively easy to reduce Yellow Rattle. Rolling or chain-harrowing the field in April or May will severely reduce it. The later you leave it, the more effective rolling is. However, you run the risk of damaging other seedlings in the meadows, such as orchids. Graze in May and June. Cut in mid-June or allow the grass to grow over winter so the seeds can't germinate. I prefer to roll in late April and not stock the fields after a crop has been cut. That should do the trick and allow maximum grassland perennials to thrive in the meadows.

 

Weeding

Watch for creeping thistle, Sow Thistles, Spear Thistles, Ragwort and Docks. Dig up as soon as they appear in the spring. We also control Hogweed as it spreads in meadows. You may also see more species than another and this may indicate that you may need to alter your cutting date to favour other species instead. Try an early cut and have a mosaic approach to your meadow where you rotate your cutting from early June to Late September. 

 

Environment

Avoid areas shaded by large trees, as the seed will struggle to germinate. Where trees cannot be avoided an early spring cut to remove excess grass ensure that the fallen leaves are removed as soon as possible in the autumn. This will reduce the fertilisation of the ground by leaf mulch and allow the seeds to get the full effects of the cold and light. Dry banks can also be challenging as they often dry out, taking the Yellow Rattle and finer grasses out. Try introducing some Plantain into the bank as a drought-tolerant ground cover and some meadow grasses. Wet and boggy ground will support Yellow Rattle as long as it can be cut short in the Summer and grazed in the Autumn. If it is too wet to manage in the winter, then consider choosing some patches that can be easily managed within the area.

see our planning a meadow advice page:

Goren Farm has signed up to Flora's local terms of code of practice to sell only high-quality local provenance seeds. 

Please speak to Julian for further advice.