A: If you are asking whether they work, the answer is yes they do. They are always worth considering if you need to speed up establishment and where you are looking for dense root development. But don't think of coatings as substitutes for good seeding practices. You should choose a good mixture to match requirements, prepare the ground properly and sow the seed in the recommended volume per square metre.
Germination is a stressful time and while the viability of seed in the bag may be as much as 99 per cent if you have bought from a reputable source and stored/handled it correctly, you cannot control ground conditions and the weather at the time you need to sow.
If you only have a narrow window in which to complete renovation work or establish a new sward, you need to be assured of quick germination, rapid development and quicker maturity of a dense sward that will out-compete Poa annua and weeds and will be capable of standing up to pests and disease.
There are several coatings available and you should talk to the seed house if you have already decided on a particular seed mixture. A new seed coating that is causing a stir in the industry is a liquid coating from Rigby Taylor. It's called ESP coating - that stands for Enhanced Seed Performance - and I had the opportunity of hearing about the trials and research at an Institute of Groundsmanhsip "IoG in Action" day held at Bridgwater College in March.
ESP coating is the result of work between Rigby Taylor and breeding partner TopGreen to ensure that using a liquid spray would coat the seed evenly and would not affect weight or the number of seeds in the bag.
Important ingredients in the coating include carbohydrates and amino acids to reduce stress during germination and seedling development. Humic acids and micronutrients are also there and zinc plays an important role because it affects the development of root hairs.
In trials, ESP was shown to encourage rapid and improved establishment, with root mass increasing on average by over 20 per cent. A greater number of secondary and tertiary roots were noted - a vital factor if you are looking for density and uniformity.
The trials in the laboratory and at Twickenham Stadium, West Cornwall Golf Club and Aberystwyth looked at different species of grass, varieties within species and the effects of soil type and temperature. Good development of roots and shoots was noted in bents and fescues. Varietal differences were observed in perennial ryegrass but, on average, an improvement was shown.
In cold temperatures, ryegrass development was significantly improved. Coated seed was also sown into sandy and clay soils. Significant benefits were observed across the trials. Improving root mass is beneficial in terms of water and nutrient uptake.
Rigby Taylor's Mascot ranges already benefiting from ESP coating cover fine turf and sports and landscaping situations. They include R105, R117, R14, R311, R314 and R9. More mixtures with this treatment are expected to follow.
Other seed houses offer coatings to enhance germination and establishment. Limagrain UK now treats all seed in its MM range with the bio-stimulant Headstart to improve establishment.
- Sally Drury has reported for HW and its forerunner GC&HTJ for 27 years and has spent more than five years testing machinery for HW and What Kit? The advice in this helpline is independent.