Have you taken these tips into consideration before choosing your grass mix?

If you looked out across the countryside this week you were bound to see grass scattered for silage or a field recently reseeded.

When it comes to reseeding, picking the grass seed mixture can sometimes be the most difficult part.

However, during a reseeding demo held by Glanbia, Mary McEvoy – a technical development manager with Germinal – outlined some key things to consider when picking the most suitable grass varieties for a reseeded sward.

The first thing to do, Mary explained: “Is to make sure the varieties you are choosing are either on the pasture profit index (PPI) or the recommended list.

“Essentially, what the PPI does is quantifies in €/ha/year how much one variety can deliver over another – like an EBI for grass varieties.”

Also Read: 5 steps to the successful establishment of a new reseed


According to Mary, the most important trait to look at “when choosing a grass variety is quality”.

“There are big differences in quality between varieties. The difference between the best variety and the worst on the PPI is €94/ha/year.

This is why it is so important that the mixture you are sowing today is of high quality, because it will mean a lot more money on the farm over the next eight to 10 years.

Touching on why these differences exist, she said: “For each one unit increase in dry matter digestibility (DMD) this means an increase of about 0.25L of milk/day – so you can see the difference that is going to have on your milk cheque.

“The reverse of that is lower-quality varieties have more fibre going into the rumen – so they fill the cow up quicker – and she will be eating less of a lower-quality feed. This will have a knock on effect on the performance of the cow.”

Diploid vs. tetraploid

Every grass variety is either a diploid or tetraploid. When choosing your mix it is advised to have a “50:50 mix of diploid and tetraploid varieties”.

“The diploid varieties bring the density to the sward – and act like a carpet underneath the cows – which reduces the risk of poaching. So, if you have heavy ground, diploid varieties are important.

Tetraploid variety

“Tetraploids, on the other hand, have a more upright growth habit, have a larger leaf, are higher in quality and we have seen higher intakes and performance from tetraploids.

“But the downfall is they are more open, so they are more susceptible to poaching on heavy ground.

“This is why we use mixtures, to get the right balance between the qualities of each,” explained Mary.

Heading date

Finally, Mary explained why the heading date of the variety should be looked at: “This is when the variety begins to develop a seed head and when this happens the quality begins to deteriorate.”

For silage swards, she said: “You want the heading date happening later than your target cutting date to avoid low-quality silage.

“For the mix you want a narrow range of heading dates – up to seven days for silage and 10 days for grazing. For grazing, you have a bit more flexibility because generally you’re going in and grazing it every 18-21 days anyway.”