Choosing whether to go for a full reseed or to overseed can feel like another difficult decision - so feel free to use our field indexing system as a guide.

Generally we suggest that:
Field Indexing 2 – 4 = overseeding
Field Indexing 1 = reseeding

Remind yourself of Step 1, which includes the field indexing system

A selection of information guides and advice to help you with grassland management. Click below to skip to the section

Benefits of overseeding

Steps to seeding your field

After seeding

When to graze after seeding

First graze & cut after seeding

Weed control

Seven Habits Of Highly Effective Grassland Management

Don’t be afraid of overseeding - A short- to medium-term fix
Currently only around 2% of UK grassland is being oversown. Overseeding is a short- to medium-term option but it does provide a quick fix and is ultimately an effective method of improving productivity - while keeping investment costs to a minimum.

Overseeding is ideal for farmers who need to improve grassland performance to help boost profits but, understandably, feel nervous about investing in a full reseed or taking a field out of rotation.

While brand new swards will always outperform older grasses, overseeding can help to increase dry matter yields short-term – reducing farm reliance on expensive bought-ins and even improving live weight gains. Implemented carefully, overseeding has the potential to improve pasture productivity by between 30 to 40% for between three to four years, depending on field quality.

When overseeding, it is crucial to use a mixture designed specifically for this purpose. Any existing productive grasses in the ley already have an established root system and an established leaf canopy to capture light for photosynthesis. Any new grass seed that is introduced needs to be able to work with these conditions and overseeding mixtures are blended accordingly. Typically, they contain tetraploid perennial ryegrass varieties whose seeds are larger, have more aggressive growth habits and are faster to establish within an existing sward. As well as tetraploid-based varieties, introducing clover could be another option.

Clover can fill in gaps to reduce weed ingress. It can also improve nitrogen levels – encouraging tillering, which makes swards denser. Crucially, clover can also encourage higher voluntary intakes, improving live weight gains.

For fields beyond repair and needing rejuventation.

Reseeding grassland can feel like a major investment, especially if you’ve got a big farm, but you shouldn’t underestimate its importance. Did you know that in order to just ‘stand still’ in terms of grass quality, you should, ideally, reseed a minimum of 10% of your grass every year! While a 15% reseeding rate will start to deliver real gains - and make a difference to your bottom line. Conversely, fields that are not reseeded will quickly become overrun with weed species with little or no nutritional value.

1 

Dig a soil assessment pit to look for compaction and plant rooting structure, which should go 30cm deep in a perennial ryegrass/ Timothy sward.

Address compaction with aerators or sub-soilers as needed.

2

Soil testing (4” deep) would also be advantageous as high levels of water can leach nutrients and reduce pH significantly.

Assess what plants are there – learn to identify what species you want to have e.g. perennial ryegrass/Timothy. Check for weed grasses,
they are usually shallow rooted and pull out very easily.

If they make up more than 30% of the sward, harrow hard to remove them.

With a sward of more than 70% weed grasses the best option is to reseed the sward.

3

Minimise competition to new seedlings by grazing tightly with sheep or taking a silage cut. DO NOT fertilise before overseeding.

4

Control perennial weeds before seeding by spraying with a selective herbicide.

5

Use a spring tine harrow to remove any dead stalks, thatch and shallow rooted weed grasses. Make sure that the tines are working the top 1cm of the soil as this will create the seed bed for the new seeds.

6

Choose a grass seed mixture designed for the job.

Sow when the soil conditions are neither excessively dry nor wet and use a specialist mixture designed to establish rapidly.

7

Roll the sward to ensure good seed contact with the soil to conserve moisture.

8

Graze lightly when the seedlings are 10cm high and continue at frequent intervals until the plants are well established.

After seeding your field, you should consider this ley as ‘establishing’ for the first 12 months. Many new leys achieve high DM yields in the first year, even though their rooting structures are often poor and management during the first year is critical to achieve longer-term persistency of growth and performance.

The better the underground rooting system, the better the plants are able to withstand future adversity.

Generally, but not always, the more cover there is, the better established the grass sward.

Cherish new swards like growing young stock – they are the production house of the future.

• Treat your grassland like an arable crop
• Fertiliser - New grassland responds well to light applications of N fertiliser
• Watch out for sulphur deficiency
• Early weed control is key
• Measure, monitor and test (Use the sward stick and soil sampling)
• Plan ahead and field index.

The role of first grazing is to stimulate tillering and allow light to the base of the sward, enabling clover to flourish.

Remember:

• Don’t graze too soon
• Understand how the ‘Pluck Test’ can help timing
• First grazing is not about feeding animals
• It’s about removing the tips of the plant to encourage new growth
• It’s also about ensuring clover has access to light and an opportunity to establish
• This will likely be at the 6-8 week stage under good conditions
• Light grazing should occur when a grass passes the “pluck test”
• This will accelerate the growth rate and tillering process
• Try to use the lightest stock class available
• Leave a 4-5cm stubble to allow the plants to recover quicker
• In spring, don’t let the grassland cover build up too much
• This significantly reduces quality and discourages tillering
• In autumn the plant is directing photosynthates to the root system
• The more green material it has after grazing, the quicker the plant can recover
• This will help the plant to put reserves into the root system aiding the overall persistence
• A consistent 4-5cm residual will encourage growth and tillering
• It will also help shading and suppression of white clover.

• When cutting leys, leave 8-12cm stubble
• This will allow speedy regrowth from live leaves
• Try and avoid making heaving cuts of silage within the first 12 months
• This damages plants, reduces tillering and growth.

A weed is “a plant in the wrong place”, but weeds can have significant consequences for grass leys. For example, where a field contains a 20% dock infestation, this can equate to a loss in 20% of potential grass production. This is due to the persistence of weeds competing for light, nutrients and moisture. Many weeds will thrive in newly sown leys with less competition. Weeds also love land with poorer soil conditions.

Tackling weeds is essential as they can:

• Lead to grazing rejection of surrounding plant material meaning grass is then wasted
• Reduce the overall palatability of the sward
• Decrease the overall digestibility and energy of the sward
• Be injurious when ingested e.g. thistles and nettles
• Be poisonous e.g. Ragwort (poisonous to ALL grazing animals) and buttercup
• Produce tens of thousands of seeds per year some of which can be viable for 80 years!
• Host diseases and pests, which affect other crops as well as grass
• Look unsightly – the worst field is always next to the road!
• Trials have shown that up to 15% of grazing losses can be associated with as little as two creeping thistles/m².

The UK’s grassland is always deficient in nitrogen (N), which assists with the tillering of ryegrass plants as well as overall grass health. In a new sward, a clover component will not contribute N immediately - so it is important to add fertiliser. New grass responds well to regular, light applications of N.

1. Control the area grazed each day (or rotation length) to manipulate grass eaten to meet average cover targets for the farm
2. Estimate the area and pre-grazing cover required for the animals based on the target grazing residual and adjust after observing when / if the cows achieve a “consistent, even, grazing height”
3. Make management decisions to maximise per animal production for the season not at any one grazing, the “main course principle - no dessert”
4. Treat grassland as a crop - remove grass grown since last grazing and prevent post-grazing height increasing over the season
5. Use a Sward Stick to monitor height. Maintain cover above 1800kg DM/ha in early spring and between 2000-2400kg DM/ha for the season to maximise grass growth rates
6. Manage weed control
7. Plan fertiliser programme.