Swards with a low proportion of perennial ryegrass are costing Irish farmers in excess of €300/ha/year, according to Teagasc.

Considering the cost of reseeding is approximately €600/ha; reseeding can pay for itself within two years.

Nonetheless, reseeding is expensive and it’s important to ensure you get the most from your efforts in order to maximise the performance of your sward over the duration of its lifetime. And, a good start is half the battle.

Here, Germinal’s Dr. Mary McEvoy highlights some key points to ensure that your autumn reseeding is successful.

1. Time it right

With autumn reseeding, timing is critical. Leaving it too late can have severe consequences for the successful establishment of a new sward.

The seed should be sown by the first week of September at the latest – so work back from this. If discing or power harrowing, leave three weeks from spraying off until tilling the ground.

For this to happen you then need to spray with glyphosate around August 10. If ploughing, it’s okay to do so 10 days after spraying. You could spray on August 20, if the weather forecast is favourable, and plough by the end of August.

Remember that if the weather breaks around the end of August, you can quickly lose a week or two so err on the side of caution and don’t leave it too late.

2. Spraying off

Using a glyphosate spray to kill the old sward is important, as this removes competition from the new seedlings as they are establishing.

Follow label guidelines and use the higher rate of water to ensure adequate uptake of the spray by the old grasses and weeds.

Approximately seven-to-nine days after spraying remove as much of the dead surface trash as you can by grazing or mowing and bale the trash to remove it from the field.

A lot of surface thrash makes it more difficult to create a good seedbed and, as this old thrash decays, it releases acids which create a poor environment for the seed as it germinates.

Apply lime to help counteract this surface acidity; liming is critical with min-till and direct drilling.


3. Method of reseeding

The method of reseeding in the autumn can have an impact on success and establishment of the sward.

Ploughing is the most reliable method, as it creates good soil/seed contact and buries thrash and pests. In autumn, direct-drilling can be problematic as slugs and pests can be more of an issue with autumn reseeds compared to spring reseeds.

A good contractor is important in order to get the job done right. Always ensure you are sowing into a fine, firm seedbed and roll adequately after sowing.

Guidelines for ploughing method:
  • Plough;
  • Roll;
  • Lime;
  • One pass;
  • Sow the seed;
  • Roll again.

4. Which Grass Varieties for autumn?

We always recommend that farmers choose grass varieties from the Irish Recommend List or Teagasc Pasture Profit Index (PPI).

If reseeding grazing ground focus on the high-quality, late-heading varieties with good seasonal growth.

For 2017, AberChoice is the best late diploid and AberGain is the best late tetraploid on the PPI. These should form the basis of your grazing mixture to get the maximum return from your new sward.


Generally for grazing swards the recommendation is 60% diploids, which will create the density in the sward, and 40% tetraploids, which will increase the quality and palatability of the sward.

5. Fertiliser for root and tiller development

It’s important to ensure that the new sward has adequate nutrition – generally three bags of 10:10:20 per acre are advised on index three soils.

But check your soil test results and ensure you remain within your nitrogen and phosphorous levels under nitrates regulations.


Apply the fertiliser after the seed is sown. Adequate phosphorous and potassium are essential for root and tiller development of the new grass plants.

It’s advisable to follow with nitrogen about three weeks after sowing. However, you need to ensure that you stay within your allowances and spread before the September 15 deadline in accordance with the nitrates directive.

6. Particularly problematic pests in autumn

Pests can be a problem with autumn reseeds; so it’s important to ensure all steps are taken to give the new reseed every possible chance.

Monitor the new reseed for pests and seek advice if you think you have a problem. To see if you have a problem with slugs; leave a fertiliser bag, pinned down with a few stones, in the field overnight.

Check the fertiliser bag the following morning and if you see slugs underneath it may be necessary to apply slug pellets.

There is no longer chemical control available for fruit-fly and leatherjackets; so adequate rolling can help reduce their movement in the soil.

It’s important to make sure all these steps are taken to give the new reseed the best possible start.

8. Weed Control

Post-emergence weed control is vital and the most cost-effective opportunity you will have for weed control in the new sward.

Apply approximately six weeks after sowing when weeds are actively growing. Ensure the product label allows use in your time frame.

It’s important to note that some new ley sprays are not permitted for use after August 31. Therefore, it’s important to check the label to ensure that you are cross compliant. If you have sown clover, use a clover safe spray.

9. Early grazing

It’s also important to check the label on your post-emergent weed spray to see when the sward can be grazed. In most cases, this is usually one week following application.

This early grazing is critical to help tillering of the sward. Graze once ground conditions allow and the new grass withstands the pull test. A sward passes the pull test when you pull the leaves and they break off and the root of the plant remains in the ground.

Often cows will do a better job than calves. Although they are heavier, they will graze quicker and can be removed from the new reseed much sooner.

Grazing in autumn, once ground conditions allow, will ensure you have a more dense and settled sward by the following spring. Click here for more information