These days, with the heavy emphasis on achieving maximum production from our pastures, the ‘preferred’ species are perennial ryegrasses and white clover. Yorkshire Fog (or velvet grass as it is known in the US) is generally regarded as a ‘nuisance’ grass, almost classified as a weed.
And yet, when I dived back into writing on grasslands done in the 1970s (Grasslands of New Zealand by Sir E Bruce Levy, 1970 and The Grasslands Revolution in New Zealand by P W Smallfield, 1970), I discovered that Yorkshire Fog played a significant role in pasture development and management in the early days of farming, particularly on the Central Plateau of the North Island and the Waikato.
When allowed to grow to maturity, Yorkshire Fog’s greyish green hairy leafage renders it less palatable than smooth and shiny varieties of grass. Its most palatable and useful period is when kept short by regular hard grazing. Its food value is never as high as the modern ryegrasses, but if animal production is not your highest requirement, then it has less well known advantages.
It likes moist feet, so will grow well in swampy areas, or peat land which is not dried out. It can tolerate dense shade or open and sunny conditions, but will fade out in areas with dry soils and intense sunshine. It grows fastest in spring, but also continues to grow all year round, when other species wither in summer.
In earlier times, when regular fertilising with high grade products was not available, seed of Yorkshire Fog was mixed with those of cocksfoot, Italian ryegrass, crested dogstail, browntop and red and white clovers. Fog’s contribution was the ability to grow all year round and, more importantly, its high ability to add humus to the soil as the dying shoots form a mat which rots down. Moreover it generously gives way to better grasses without much trouble when these become established. While it grows in moderately fertile soils, it won’t tolerate high fertiliser levels, but will cope with depleted soils when other grasses fail to establish.
Along with velvety grey-green leaves, it has round shoots, which are white with pink stripes at the base. The inflorescence (seed head) is soft, whitish, and often tinged purple. It seeds prolifically and rapidly colonises damp disturbed ground, often round drainage ditches and in areas of heavy shade. The seed head stalks are about 60cm tall and the plants tend to expand into new territory from central clumps.
If your land is not being used for maximum production, then getting rid of Yorkshire Fog need not be a high priority. Limiting grazing areas so that it gets eaten down, or mowing it occasionally will discourage it from seeding, limit its spread, and provide feed of moderate value all year round. I read recently that Massey research has shown that Yorkshire Fog, along with other currently unfashionable pasture species, actually contains higher levels of trace elements than ryegrasses, so it may be quite useful to have around, after all!