Guide to growing grass seed for mixed farmers

Grass seed is a “high-risk, high-reward” crop that can prove hugely profitable for good mixed farmers with an eye for detail.

Some 8,000ha (20,000 acres) of grass seed is grown annually across the UK for both the forage and amenities sectors, with the forage crop potentially generating a gross margin of more than £1,000/ha (£405/acre).

Germinal produces 70% of the country’s forage grass seed, with about 85 farmers growing it for them. The majority produce certified perennial ryegrass seed.

Prior to the final stage of on-farm production, each variety will have gone through a 15-20-year selection process involving Aberystwyth University and Niab testing.

See also: The benefits of growing and feeding lucerne to dairy cows

After such a lengthy process, Germinal’s seed production manager John Fairey is choosy about which farmers grow the final certified seed. “Grass seed growers are very good farmers. The reason is, like a lot of crops, we’re struggling with chemicals and control of grassweeds,” he says.

“It’s important that farms that grow grass seed don’t have an underlying issue with blackgrass or wild oats.”

This is vital to ensure the end user receives a pure seed that does not include any unwanted species (see “So you want to produce grass seed?”, below).

Mr Fairey provides a step-by-step guide to growing grass seed and explains what type of farmers it best suits.

1. Take a different attitude

Growing grass seed is completely different to growing grass for forage. Rather than producing vegetation, you want the plant to tiller and produce seed. 

2. Get soil indices right

As with any crop, soil indices should be optimal before establishment to promote top performance. Aim for P and K indices of 2 and a pH of 6-6.5.

3. Choose your drilling date

There are two options for drilling date:

Autumn drilling

  • Drill as a standalone crop by 15 September. This is attractive for arable farmers looking to drill after a wheat crop.
  • Better suited to heavy land, where it can be difficult to get a seed-bed in the spring.
  • Grass seed is harvested the following July.

Undersowing grass with spring barley

  • This is the preferred option as it gives greater opportunity for grassweed control later in the year, once the barley is harvested.
  • After the barley is harvested, fertiliser can be applied and the grass can be grazed from September to February – making it ideal for weaned lambs.
  • Grass seed is harvested the following July (after the year of establishment).

4. Create a fine, firm seed-bed

Farmers can choose to use whichever establishment method suits them. As with any grass ley, a fine, firm seed-bed is vital.

This is even more important with grass seed production because it is sown at a lower rate of 10kg/ha (4kg/acre), versus 37kg/ha (15kg/acre) for a conventional grass ley. Seed should be rolled in at least twice.

5. Fertiliser

Because you need to produce a seed head, large, early applications of nitrogen should be avoided. Nitrogen application of about 160kg/ha N should be split into three applications so there’s enough left for the seed head.

It’s worth applying 15-30kg/ha of sulphur in one of the dressings. Maintenance dressings of P and K will also be needed. Rates will depend on soil indices.

6. Herbicides and pesticides

If the crop is established in a fine, firm seed-bed, slugs and flea beetle should be less of a problem. Ploughing will also help with weed control.

7. Harvest

Grass seed is harvested for two years using a combine with either a draper header or a stripper header.

Grass seed harvest options – pros and cons

Harvest method

What is it?



Draper header

•  Grass is mown when there’s about 45% moisture in the seed.

•  The crop is left in the field for five to six days to dry.

•  The whole swath is picked up using a draper header and the seed is thrashed out.

•  The sun does most of the drying for you, saving on drying costs.

•  Thrashed hay can be dried and baled or wrapped as haylage behind the combine.

•  Can be grazed afterwards or N applied and silaged later.

•  Risky in catchy weather as the rain can knock the seed out so it goes to waste, potentially making the crop valueless.

Stripper header

•  A stripper header strips the seed off the standing stalk leaving a long stubble behind.

•  Cut at 30% moisture.

•  Greater flexibility regarding when you mow the stubble. Can make hay or haylage.

•  Less risk.

•  Higher drying costs. Crop needs to be dried down to <14%.

8. Drying

This is the most difficult and important part of the process. The seed has to be <14% moisture for collection. If the crop heats up during the drying process it will affect the germination rate.

A failed germination test will make the crop worthless. It’s vital the crop is dried quickly and evenly on a drying floor. It should be stored no more than 1m deep and turned regularly. The seed must be monitored constantly during the drying process to avoid problems.

So you want to produce grass seed?

Ideally suited to mixed systems: A four-year break must be left between grass crops. You will also need a drying floor.

Location: Can be grown on most soil types. Need to consider what crops are grown adjacent to a grass seed field. If similar ploidy varieties (diploid or tetraploid) are grown next to each other, steps need to be taken to avoid cross-pollination.

Inspections: Inspectors will look at the standing crop. They will inspect different plants in the crop and what’s grown in the neighbouring field. Niab will also do its own inspections.

Testing: Once the farmer is satisfied the seed is ready for collection, a sample will be sent for dry matter and germination testing. Once identified as ready for collection, the crop goes to a cleaning facility before being put into bags for sale. 

Contract: The farmer is responsible for growing, harvest and storage of seed. Germinal supplies the seed and pays the farmer based on them meeting their obligation for moisture (<14%) and germination.

The grower also pays a proportion of the seed cleaning costs (to encourage the production of a clean, weed-free crop). Cleaning charges are worked out based on the purity of the crop.

Benefits: Grass fits neatly into arable rotations, providing a useful two- to three-year break between crops and improved soil organic matters. It also provides additional forage options for livestock.

Sheep in particular fit nicely into its production cycle, providing a useful weed-control strategy.

Case study: Dorset mixed farmer James Reed

Grass seed is proving more profitable than first wheat for Dorset mixed farmer James Reed, who is also seeing the benefits in improved soil health and extra forage.

“It has the potential to build organic matter and it’s a more attractive gross margin than some; for me, it’s better than first wheat,” he says.

Mr Reed farms 404ha (1,000 acres) at Upwood Farm and grows 50ha (120 acres) of the late-heading, tetraploid perennial ryegrass AberBite for Germinal. The crop is undersown with spring barley as part of the arable rotation.

The crop is harvested using a draper header, with the aftermath grazed by the farm’s 45 Aberdeen Angus cross Hereford suckler cows and followers.

The threshed hay is then baled. A proportion will be sold and some will be fed to the suckler herd over winter as part of a TMR with fodder beet and wholecrop.

Mr Reed also has an arrangement with two local shepherds who graze the aftermaths with their sheep from November to February. “The sheep are important to growing [grass seed],” he explains.

“They eat the weeds and hold the crop back until you want it to grow. And you’re getting sheep across your rotation. You’re getting manure spread back on the ground.”

Mr Reed has his own draper header and also employs the services of neighbouring farmer Nigel Friend, who has the same equipment. Mr Friend also grows a variety of seed crops at Lower Farm, Gussage Saint Michael, including 140ha (346 acres) of grass seed for Germinal.

He views grass seed as high risk, high reward. “It doesn’t always work and you can lose money on it,” he says.

He believes the drying process is vital to prevent heating and safeguard germination. This means immediately moving the seed from the trailer to the drying floor to cool and moving the seed crop every day during drying.

Being on top of weed control is also vital. Get that right and the margins can be attractive, he says.

“Grass seed is our main crop and wheat is the break crop,” he says.

Online grain trading made easy with Farmers Weekly Graindex

It takes just a couple of minutes to create a listing on Farmers Weekly Graindex and you’ll get a range of prices to compare from active buyers who want your grain.
Visit Farmers Weekly Graindex