Boost grassland production by overseeding pasture

Tuesday 16.04.2024 , News

Relentless wet weather since October has hampered turnout and fieldwork on British farms in 2024. Pasture is waterlogged across the length and breadth of the country and remedial work will be required when dry weather comes. Where full reseeds are not possible, overseeding pasture is a productive alternative.

This can give grassland a short-to-medium term boost until full reseeds can be carried out. By improving both the yield and quality of underperforming grassland, overseeding offers an early return on investment. It can increase dry matter production significantly with an increase in D-value worth 1.0 MJ/kg.

Overseeding rejuvenates pastures without taking ground out of production for long. This flexible, cost-effective option can be used in a wider reseeding programme to gain two to three more years out of a sward before a full reseed.

Choose ground carefully

When choosing which pastures to overseed, it is important to be selective. For overseeding grassland to be effective, choose pastures that haven’t yet deteriorated too far and still have at least 50% perennial ryegrasses.

Where broadleaf weeds, such as docks, thistles and nettles, are a problem, they should be controlled first to open up the sward. Allow plenty of time before sowing to avoid any residual chemical affecting the seedling establishment – particularly clover.

If there is an issue with weed grasses, a full reseed is likely to be more cost-effective than weed control.

Prepare well for overseeding pasture

The ideal period for overseeding pasture is from now until September when conditions are warm and damp. Overseeding grassland is less successful if followed by dry conditions, so try to pick a time when rain is forecast with no risk of drought or extended dry spells.

The right soil conditions, including fertility, structure and nutrient status, are also important. Any existing issues could be the reason your existing sward is performing poorly so it is worth taking the time to correct these first.

soil test image

Carry out a soil test and examine your soil well in advance of overseeding so you have plenty of time to correct any shortfalls. For optimum sward performance, pH is 6-6.5 with P and K indices at 2, so apply fertiliser as necessary to achieve these levels.

But it is important to avoid applying nitrogen to reduce the growth and competitive nature of existing species. Allow time (at least six weeks) for spring applications of organic and inorganic nitrogen to have been used.

The best grass seed for overseeding pasture

Germinal’s Aber HSG Overseeding mixtures are specifically designed to establish rapidly by blending into your existing sward. Containing larger tetraploid seeds, these varieties are better able to grow alongside your old pasture.

We have short-term and long-term options that offer these benefits:

  • Rapid establishment
  • Increased dry matter yields and D-value
  • Reduced ammonia emissions from livestock

Overseeding clover

Mid-summer is an ideal time for overseeding pasture with clover as soil temperatures are warm and grass growth is slowing down. This can be achieved by using similar establishment methods or by sowing an overseeding pasture grass seed mixture with clover.

Choose the Germinal white clover blend best suited to your system:

  • AberSheep contains smaller-leaved varieties for sheep grazing;
  • AberPasture also includes medium-leaved varieties for cattle and sheep grazing systems;
  • AberDairy contains medium and larger-leaved varieties for dairy grazing and cutting systems. 

Red clover can also be introduced to boost silage yields and homegrown forage protein production, as well as reducing nitrogen requirements. However, please be mindful that overseeding red clover is more difficult and a full reseed will be more effective.

Sow white clover at 1.5 kg/acre and red clover at a minimum rate of 2 kg/acre. 

white clover and grass sward

The best way to overseed pasture

Seed-to-soil contact is particularly important when overseeding and soil must be visible when sowing or seeds will struggle to germinate. Start by either grazing down the pasture tightly or taking a heavy silage cut. This helps reduce competition between new seedlings and the existing sward.

It is important to harrow hard into the old pasture to open the sward up, remove thatch and help create some tilth. Seed can then be broadcast and rolled. Sow at 25 kg/ha (10 kg/acre) at a sowing depth of about 15 mm.

As a rule of thumb, avoid drilling seeds deeper than one and half times the size of the seed. Direct drilling can work, but you must harrow well and roll to press the seed in.

Immediately after sowing, leave stock in for about a week to keep the old sward grazed off. At the first signs of germination, remove livestock and monitor the establishing seedlings carefully.

Graze lightly once seedlings have reached the three-leaf stage or 7-10 cm and stand the ‘pull test’ (for example, it can’t easily be pulled out of the ground, to aid tillering).

Overseeding pasture advice

Contact our grassland experts if you want to know more about overseeding pasture or would like advice on choosing the best mixture for your farm's conditions.

William Fleming, Area Sales Manager, Scotland and North England

T: 07971 640428


Paul Morgan, Area Sales Manager, South England and South Wales

T: 07713 878069


Harley Brown-Keech, Area Sales Manager, Midlands and North Wales

T: 07880 469645