08 April 2025

Watch: Dr. Michael Egan’s tips on establishing grass/white clover swards

Focusing on paddock selection, timing, establishment method and post sowing management, Researcher in Teagasc Moorepark, Dr. Michael Egan shares his key tips on establishing grass/white clover swards.

Establishing white clover on farm will take some time, using a combination of both reseeding and over-sowing.

Incorporating white clover in a full reseed is the most reliable method of clover establishment. Over-sowing is a simple and low-cost method of introducing white clover into swards. Success is very much dependent on soil fertility, weather conditions at over-sowing and post-sowing grazing management.

In the below video, Dr. Michael Egan covers the key considerations when establishing grass/white clover swards:

White clover establishment blueprint

A targeted multi-year approach should be used in establishing a white clover system, which is a combination of reseeding and over-sowing:

• Reseed approx. 8-10% per year
• Over sow approx. 20 % per year
• Year 1- reseed 10% and over sow 15% = 25%
• Year 2- reseed 10% and over sow 15% = 25% (50%)
• Year 3 – reseed 10% and over sow 15% = 25% (75%)
• Year 4 – reseed 10% and over sow 15% = 25% (100%)
• Year 5 + – on-going process

Reseeding

A spring reseed – April, May – provides the best results, and some key tips to note include:

• Spray off the old pasture with glyphosate
• Prepare a fine, firm seedbed (with the most appropriate cultivar method for that paddock).
• Soil sample and apply required lime, P and K
• Use the Irish Recommended List for grass and clover cultivar selection
• Follow the recommended sowing rates as included in table 1 below
• Ensure good seed:soil contact by rolling after sowing

Table 1: Recommended sowing rates for grass and white clover

Over-sowing

Key things to consider when over-sowing include:

• Control weeds the previous year prior to over-sowing white clover
• April/early May is the best month for over-sowing
• Over-sow directly after a tight grazing
• A number of methods of over sowing are available for white clover (see Figure 1)
• Ensuring soil contact post over-sowing is one of the most crucial factors
• Over-sowing methods – all methods in Figure 1 below, are equally successful as long as the right conditions and post management are correct
• Broadcasting –  gives more varied results:
  • Mix clover seed with a compound fertiliser in the field – max of 1 ha at a time
• Stitching – can ensure a better soil: seed contact:
  • In sheep swards stitching should be used
• Sow at a rate of 5 to 6 kg/ha

Figure 1: Methods of over-sowing white clover into existing swards

Post-sowing management (full reseed or over-sowing)

Having light available to the base of the sward is a crucial factor in post management, this encourages stolon development. The first grazing should be at a pre-grazing herbage mass of 600 to 1000kg DM/ha. The subsequent three grazings should be at a pre-grazing herbage mass <1,100kg DM and graze swards to ≤4 cm (graze tight) – this will mean that paddock grazing times will be much reduced in these paddocks. Additionally, no silage should be cut from the over-sown paddocks in the first 12 months after sowing, and swards should be grazed later in the autumn to avoid carrying heavy covers over the winter.

Weed control

Weed control in reseeded and over-sown grass/white clover swards is vital to improve sward persistence. Clover safe herbicides should be used in establishing and established swards. All pesticide users should comply with the regulations as outlined in the Sustainable Use Directive (SUD).

Reseeds

Weeds are best controlled when the grass plant is at the three-leaf stage and the clover when the trifoliate leaf has appeared. White clover safe herbicide should be used.

Over-sown

Established weeds should be controlled the previous year before over-sowing. Consider the residue time of non-clover safe sprays (this may effect clover establishment).

For more information on clover management and establishment please see Teagasc Clover Manual here.