Skip to Navigation | Skip to Content

To contact one of our “Forage for Profit” team, call the Seed Office on 01769 576232
or Graham Ragg on 07798 583667
or email

Compelling reasons to reseed

There are three sound reasons to reseed or replace existing leys that are not visually apparent. These are:

1 Age of ley

2 Sward deterioration

3 Improved output and profitability

1 Age of ley

New grass varieties take 10 to 15years to develop, test and market and generally have a 10% better performance than those used in old leys.

Considering grazing varieties, the intermediate perennial ryegrass Aber Star is the highest yielding on the 2010 NIAB Recommended List and offers a 1.1 t DM/ha advantage over the lowest yielding variety on the list. Using the Kingshay cost of production for grazed grass figure of £79/t DM, this gives a ‘top to bottom’ financial benefit of £87/ha.

Similarly, considering first cut silage yields, where the highest third year yield comes from the new perennial ryegrass Aber Bite (offering 1.94 t DM/ha more than the lowest yielding on the list), the ‘top to bottom’ advantage based on Kingshay’s first cut forage cost of £109/t DM is an astonishing  £211/ha.

In addition, new varieties that are marked have higher digestibility and greater palatability leading to greater intake and performance. So higher yield is only part of the story, as the difference between best quality and poorest quality on the Recommended Lists is even more striking. The ‘top to bottom’ differential on grazing D-value on the NIAB lists is five points, with Aber Star, again leading the way at 79.2 D compared with the lowest at 74.2 D, again leading to significant financial benefits.

One unit of D-value improves animal performance by 5%, so even within the list, the difference between the best and worst performers could be as much as 25%. Alternatively, DARD in Northern Ireland equate one unit of D-value to 0.2kg/cow/day of dry matter intake and 0.4kg/cow/day of milk yield – that is 2 litres/cow/day extra from using the best listed variety instead of the worst listed.

2 Sward deterioration

Through age, poaching, wheel damage and inadequate fertiliser application; all of these allow the ingression of weeds and weed grasses which are markedly lower yielding, less responsive to fertilisers and less palatable. Consider their impact on performance when they comprise up to 50% of the ley! Perennial ryegrass needs soil indexes of 2 for P and K to stay dominant, below that, they start to die out from year one. Consider the benefits of getting the soil pH and fertility right and of reseeding with a new ley using the best varieties’.

3 Improve output and profitability

On farm costs for a full reseed are estimated to be £280/Ha. The benefits indicated in 2 above when compared with what is a good average aged ley, are;

The gain from the reseed being 2,080kg of grass DM/ha, equivalent to £220 to £300 if food has to be purchased to make up any short fall, or enabling more cattle to be kept on the same field resulting in more productively. The reseeding costs would be recouped in two years and were the old ley in poorer condition the payback would be faster and greater!

View our main grass seed mixes.

For more advice on re-seeding and the options you have, read on or call your farm sales speciality or the Seedline on 01769 576232.

Re-seed options

Only a close inspection can tell whether to re-seed, and the best way to find out is to walk the field across both diagonals estimating the percentage of bare ground, obvious weed (dock and nettle) cover and amount of ryegrass remaining. Identify the ryegrass by pulling plants at regular intervals and checking that they have a crimson-red base to their stems. Any grass with out this is a weed species unless timothy or cocksfoot was sown in the original ley. Of critical importance to the decision, is the fact that perennial ryegrass is a single tufted plant that does not spread. Unlike a number of the weed grass it has no runners and will not fill bare patches bigger than a saucer. Therefore, unless the ryegrass plants are evenly spread across the field and make up 50% of the herbage present, a full reseed is the most cost effective solution over the lifetime of the pasture. A full reseed presents the opportunity to put in a new ley using the best varieties with close heading dates to have better silage quality and fit for the purpose. It also has the advantage of an extended life which reduces the annual cost.

Over-sowing done properly may be half the cost of a full reseed and has the advantage of being returned to the grazing cycle much faster.

Under-sowing advice

1. Cut back the cereal sowing rate by about 20%, spring barley sown at 50-62.5 kg/acre (125-155kg/H) is ideal.

2. Chose a variety with good straw strength and resistance to lodging.

3. Cut the fertiliser back by a similar amount to the cereal seed. Don’t try to get two massive crops; it is better to get a reasonable cereal yield and a good ‘catch’ of grass rather than a massive cereal crop that smothers the grass.

4. Alternatively, and probably the best solution, is to cut for silage as the grain starts to harden. This lets the light into the young grass and clover seedlings earlier and strengthens growth.

5. Sow the cereal first and then roll to firm the seed bed, before sowing the grass in the top 0.5cm of the soil. If a perennial ryegrass mixture is sown, one operation can follow the other, but if an Italian ryegrass mixture is to be sown, allow the cereal crop to become established and about 5cm tall, before sowing the grass seed. This gives the cereal a head start on the Italian as in a wet summer, sown t the same time, Italian will out grow the cereal, causing major harvesting problems.

6. If, despite your best endeavours, the crop shows signs of lodging, cut the crop as whole crop silage rather than risking the grass seedlings.
7. After harvest, remove the straw as soon as possible, fertilise the grass and graze tightly, this will force the grass plants to tiller and will rapidly thicken what will look like a very thin sward following the cereal harvest.

Identify ryegrass by the plant’s crimson-red base

For more information about the MVF range of grass seeds, contact your local Farm Sales Office or call the SeedLine on 01769 576232.


  • Minimise competition by grazing sheep or cutting for silage, prior to sowing.
  • Do not fertilise or spread slurry on the field before overseeding.
  • Control perennial weeds before seeding by spraying with a selective weed-killer.
  • Sow when the soil conditions are neither excessively dry nor wet. In dry weather, follow sowing with a heavy roll to conserve moisture.
  • Harrow the existing sward hard, this will remove thatch, weed grasses and weeds and create a fine, shallow tilth. Spring tine harrows are ideal for this job
  • Sow a specialist overseeding mixture, which contains varieties of perennial ryegrass and white clover that are aggressive enough to establish against the existing plants.
  • Roll the sward following sowing, ideally with a Cambridge roller that will not cap the field, but will incorporate the seed at the right depth
  • Apply a suitable insecticide for control of leatherjackets for spring, early summer sowings and frit fl y for late summer, early autumn sowings
  • Graze lightly when the seedlings are 10cm high and continue at frequent intervals until the plants are well established.

Store Locator For website enquiries and online orders phone 01769 576419 (8.30am - 5.30pm 5 days a week)