Biology of Nettles
There are numerous nettle species world-wide, many of which are trees or shrubs. Within Europe only two occur as weeds:
Urtica urens – annual
Urtica dioica – a perennial and the most prevalent species in established pasture
- Propagates mainly from extensive, creeping, rooting stolons.
- New plants are able to develop from root sections, so that chopping them does no more than multiply the problem.
- The more often the shoots above ground are cut, the more vigorous is the new growth.
- They will grow upto a height of 1 metre, eventually forming dense beds, which spread out across the field.
- Flowering period is from June to October.
- Germination occurs from the soil surface, even at low temperatures, when the grass sward becomes open or if the soil is disturbed.
Impact on the sward:
- Grass yield / grazing is lost mainly by competition from nettles for nutrients, light and moisture, but also from stock refusing to graze close to nettles.
- The quality of the conserved grass (hay, silage) is affected if nettles are present, as the stock will reject it.