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Grass seeds & mixes: How to select grass seed mixes to suit requirements

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The types of grass you select can have long-term implications on grassland performance, so it is well worth taking the time to match your mixes with your system requirements.

Adam Simper says before doing any reseeding, it is important soil testing has been carried out.
Adam Simper says before doing any reseeding, it is important soil testing has been carried out.

How many times have you just taken the grass mix your merchant has suggested without questioning whether it truly suits your needs on-farm and includes tried and tested varieties?


According to Adam Simper, grass and root seed product manager for Wynnstay, many dairy farmers could benefit from taking more time to consider the grasses they choose.


This fits with the notion of ‘treating grass like a crop’.


He says: “Farmers need to question their merchant and make sure they’re using varieties off the Recommended Grass and Clover Lists.


By using recommended varieties, the end result is higher yields, better disease resistance, better ground cover and better winter hardiness, which comes back to improved grassland performance.”


Mr Simper says before doing any reseeding, it is important to ensure all the basics are in place, which includes soil testing, correcting any nutrient imbalances, addressing compaction issues and controlling weeds.


This will optimise the performance of any new grass ley.

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Adam Simper
Adam Simper

Once confident these steps are in place, specific questions can then be asked when choosing grass seed mixes:


Q. How long do you want the ley to last?


A. Choose the right type of perennial rye-grass to fit how long you want the ley to last. A mix with early perennial rye-grasses will only last three to four years so will not suit a system which requires longterm leys.

Q. What seasonal regrowth is required?


A. Is it early spring or late autumn? Do you turnout early and need early spring growth?

Q. Which fields do you want to reseed?


A. This will impact on whether you want to cut or graze them. Also, if a field is close to the farm and gets used a lot, you may require a mix which will provide greater ground cover.

Q. What is your end goal?


A. If you want flexibility and the ability to cut and graze ground, then choose a mix accordingly. If you are doing intensive, rotational grazing, then grasses must be able to cope with this management and provide good ground cover and regrowth.

Q. Do you want to include clover?


A. If so, speak to your agronomist about appropriate clover-safe sprays and when to use them.

Q. What are the heading dates in the mix?


A. Tight heading dates between varieties included in a mix is a must for ease of management and to maximise the production of quality grass.

Q. What soil types do you have?


A. On lighter soils, a higher proportion of tetraploid perennial rye-grasses may be better as they have a deeper rooting system and scavenge for moisture better.


On heavier soils, diploids may be better as they tiller out more and provide a dense base which will help prevent poaching.

Mr Simper runs through some example grass mixes that could suit a number of different system types. (See glossary for explanation of grass types)

  • Rotational grazing – medium term, four- to five-year mixes

- Opt for intermediate and late heading perennial rye-grasses and choose an early heading, intermediate variety to provide good early spring growth.

- You do not want Italians as they will not give good ground cover or last long enough. Also avoid hybrids as they too will not give ground cover and are hard to manage in grazing systems.

- Select varieties with a high ground cover score on the RGCLs, which will tend to be diploids.

- Use a spread of diploid and tetraploids (50:50). The diploids will provide ground cover, while the tetraploids will provide quick regrowth and will be ready to graze again 18 to 21 days later.

- Choose four-to-five-year leys as a minimum.

- Select medium- or largeleafed white clover.

  • Silage-making

Select mixes based on how long you want the leys to last:

  • Short-term (two years)

- Choose Italian rye-grasses which are aggressive and quick yielding.


- Four to five cuts a year should be achievable.


- Spring-sown crops will yield better in their second year.

- Clover is not a good option in short-term mixes.

  • Medium-term (three-four years)

- Go for hybrid and intermediate tetraploid perennial rye-grass.

- Tetraploids will provide higher cutting yields and quick regrowth, and are also naturally higher in water-soluble carbohydrates which aid fermentation in the clamp.

- Use a large leafed white clover to help increase protein levels.

  • Long-term (five years+)

- Select predominantly intermediate and late tetraploid perennial rye-grass.

- Do not choose hybrids as they will not last long enough.

- In long-term mixes, tetraploids can become more open in the base, which may encourage weed ingress, so include about 30% diploid varieties to aid ground cover and prevent weed ingress.

- Use a large-leafed white clover.

Note: Tetraploid grasses have larger seeds, so when using high levels of tetraploids (>70%), use a higher seed rate of about 15kg/acre.

  • Dual purpose cutting and grazing mixes

- If grazing is more important, include more diploids, if cutting is a priority, use tetraploids.

- Avoid Italian rye-grasses as they will not last and will produce an open base which can lead to poaching when grazed.

- Tetraploids have an increased cell size due to this and have a higher ratio of cell contents soluble carbohydrates (sugar) to cell wall (fibre), indicating that they have a higher water content per cell.

- Diploid plants have more tillers per plant and due to the lower water content per cell, have a higher dry matter per kilogram of feed and also more energy than tetraploid plants. They are favoured in tight grazing situations.

Choose the right type of perennial rye-grass to fit how long you want the ley to last.
Choose the right type of perennial rye-grass to fit how long you want the ley to last.

Glossary of grass terms


Perennial rye-grass (PRG)

  • Persistent, high-quality grass
  • Use in medium-to long-term mix
  • Yields about 13-15 tonnes dry matter/hectare
  • Lower yielding than Italian rye-grass, but lasts longer
  • Can be cut or grazed

Italian rye-grass

  • Higher yielding than PRG but lower quality and less persistent
  • Yields up to 18t DM/ ha/year in the correct conditions
  • Short lived grass lasting for two years
  • Open growth habit
  • Suited to cutting regimes
  • Starts to grow when soil temperatures reach 3degC, so grows earliest in spring and latest in autumn compared to other grasses

Hybrid rye-grass

  • A cross between the Italian and perennial
  • Balances high yielding characteristics of Italian rye-grasses with persistence and quality of perennials
  • Longer lasting, high yielding species
  • Increased ground cover compared to a straight Italian


  • Italian and perennial ryegrasses crossed with a tall fescue or meadow fescue
  • Combines quality from the rye-grass with winter hardiness, persistence and stress tolerance from fescue
  • More tolerant to drought and flooding
  • Suitable for grazing, cutting or dual purpose leys on light soils

Diploid or tetraploid

  • The main difference between diploid and tetraploid rye-grass is the number of chromosomes per cell. Diploid plants have two sets of chromosomes per cell, while tetraploids have four.
  • Tetraploids: Quicker establishment and regrowth, improved first cut yields and higher water-soluble carbohydrate levels suits dry ground
  • Diploids: Denser sward, better grazing yields, high DM per kg of feed and D-value, and suits wetter ground

The Recommended Grass and Clover Lists (RGCL)

  • The Recommended Grass and Clover Lists for England and Wales include varieties which have undergone vigorous testing for attributes such as yield, persistency, quality and disease resistance.
  • As few as one in 20 varieties of rye-grasses tested will make it on to the recommended lists.
    By choosing grass and clover from the lists, farmers can ensure they select quality varieties.
    jView the RGCL at
Richard Pearman
Richard Pearman

Choosing dual purpose mixes – Richard Pearman, Woodlands Farm, Belbroughton, Stourbridge


Richard Pearman likes the flexibility of having dual purpose grazing and silage ground, although silage-making remains the priority at Woodlands Farm, Stourbridge.


Grassland on the 182-hectare (450-acre) farm is grazed by youngstock and sheep on tack over winter and also cut for silage.


With the 240-cow Holstein Friesian herd housed all-year-round and producing 10,700 litres at 3.95% fat and 3.28% protein, producing quality forage is a must.


In fact, it is an area that has had increasing emphasis placed upon it over the last two years.


During this time, Mr Pearman has moved to a multi-cut silage system, cutting every five weeks, rather than every six to seven weeks.


He has also overhauled the grass mixes he is using with the view to producing good forage, which will boost milk from forage and reduce costs.


He says: “The key to our system is forage. It has to be top notch.”


In the past, he would have chosen predominately short-term, Italian rye-grass leys. However, this created problems with grass going to head early.


With the farm a mix of these short-term leys and perennial rye-grass leys, it meant different fields would be ready at different times for silaging, which was compromising quality when ground was cut at once.

Intermediate heading

Subsequently, Mr Pearman decided to change all ground to predominately intermediate heading perennial rye-grass mixtures, without clover and 24ha (60 acres) were reseeded this year.


He says: “We’ve moved to long-term leys, high dry matter and high leaf content for high digestibility, hopefully.”


The current grass mix, Wynnstay Sovereign with no clover, includes a mix of intermediate diploids and tetraploids with a small amount of a late diploid.


This includes the intermediate tetraploid, Dunluce which produces high cutting and grazing yields and has the highest year one first cut D-value on the RGCLs.


The late diploid, AberAvon also has the highest autumn ground cover score and joint highest early grazing yield on the RGCLs.


Mr Pearman adds: “The more leaf we have – which is what we get with four- to five-year, softer grass – that’s where the quality is and it helps with the ME.”

Choosing mixes for grazing – Sansaw Estates, Shrewsbury, Shropshire

Choosing mixes for grazing – Sansaw Estates, Shrewsbury, Shropshire

Good ground cover and mid-season growth is important at Sansaw Estates, Shropshire, where the 1,600-cow springcalving herd grazes for 10 months of the year.


As a result, the estate’s managing director James Thompson chooses mixes with intermediate and late heading perennial ryegrasses. This season he is also looking to increase the proportion of diploids in the mix to improve ground cover.


He says: “We have used more tetraploids and have had gappy pastures, so we have tried to put in more diploids. I like the diploids for ground cover. As soon as you start opening up pasture, you get broadleaf weeds that outcompete the grass,” he explains.


With cows stocked at three cows/hectare (1.2 cows/acre) on the 500ha (1,235-acre) grazing platform, having a good base to the sward is essential to limit poaching. The herd calves in a 12-week block starting on February 1 and produces 5,000 litres per cow per year and 440kg of milk solids per head.


Up until this year, cows have been grazed from the start of February to the end of November, before being out-wintered on fodder beet. However, out-wintering will come to an end in 2019/20 and cows will be housed instead. This will ease management and allow greater control of body condition.

Grazing period

During the grazing period, the herd is rotationally grazed on 12- or 24-hour breaks, entering paddocks at 2,800-3,200kg DM/ha and grazing down to 1,500-1,600kg DM/ha.


The estate opts for longterm grazing mixes, reseeding pasture about every 10 years. Going forward, the aim is to base reseeding decisions more closely off pasture dry matter production data, recorded using a grass plate meter.


This season, the estate will be using a mix of intermediate and late heading perennial ryegrasses, which includes 60% diploids and 40% tetraploids. This will be sown at 14kg/acre, including 2kg/acre of a blend of medium leafed white clover.


The mixture includes AberAvon, which has the highest autumn ground cover score on the RGCL and good grazing D value. AberGain has also been selected due to its highest grazing yield and D-value. Mr Thompson views white clover as a crucial component in any grass seed mix. He says: “Clover is essential. It fixes nitrogen, plus you produce more dry matter with clover in the sward and more milk solids. I would not be without it.”

Choosing mixes for silage – Joe Twose, Maenhir, Login Whitland, Carmarthenshire

Choosing mixes for silage – Joe Twose, Maenhir, Login Whitland, Carmarthenshire

Grass which does not go to head too quickly and also creates a thick sward that can carry machinery are the priorities on Joe Twose’s silage ground.


Mr Twose runs 450 cows in a family partnership at Maenhir, Login Whitland, Carmarthenshire. Cows yield 9,500 litres at 4.2% fat and 3.5% protein and calve from July to February. About 93 hectares (230 acres) of the 222ha (550--acre) farm are accessible for grazing. The remaining silage block lies about three miles away and is planted with long-term mixes suitable for early cutting, that will produce good overall yields. This is essential considering about 70% of the forage proportion of the diet is grass silage, with the rest maize.

Silage mix

About 20-24ha (50-60 acres) a year are reseeded in autumn using Wynnstay Royal, a silage mix, including a blend of 10kg of late heading tetraploid perennial rye-grass and 5kg of late diploid perennial rye-grass. All of the grasses in the mix head on May 20-23. One kilo of large leaf white clover is also included to aid palatability and help silage protein levels. Mr Twose says: “We don’t want grasses that head early or go stalky, so it gives us a bigger window if the weather stops us cutting for a week. I don’t want Italian rye-grasses that bolt up, as I need something that will cover the ground and keep the weeds out, withstand heavy machinery and react to fertiliser and slurry.”


First cut is generally taken at the start of May, with four cuts taken a year, leaving a five- to six-week gap between harvesting. Achieved at first cut is usually 14-17 tonnes/ha (6-7t/acre), with 12t/ha (5t/acre) on subsequent cuts. Last year’s first cut averaged 32% dry matter, 11.4ME, 74 D-value and 16.3% crude protein.

Soil sampling

Before any reseeding, Mr Twose always undertakes soil sampling to ensure indexes are correct. Ground destined for a reseed will also be burnt off to ensure there is a clean seedbed. When it comes to reseeding itself, he is also keen to use high seed rates.


Mr Twose says: “I always put on 1-2kg extra per acre to make sure I’ve got a good germination. If I go to the effort of reseeding a field, I want it to grow.”

Grassland Toolkit 2019

Grassland Toolkit 2019

Your essential guide to grassland and grass silage management.


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