- Location
- Owaka, New Zealand
Usually a symptom of poor calcium/silica cycling - they love lime every year especially if the grass is kept well pruned through the growing season.See a lot of your weed problems start with the soil condition. So thistles and other unpalatable plants are really just like billboards saying "hey! this soil is poor and/or mismanaged" as they tend to grow in poor or dried out soils.
That's the main reason they are a big part of our landscape in NZ - short rotation bordering on overgrazing, lime + TSP diet. Grass doesn't need to grow deep roots if you feed from the top, and anything that goes below the root zone feeds the thistles (other than the compactiom issue it's trying to remediate)
In a damp climate, growing deep-rooted species may or may not work, more a tactic for dryland farming when moisture in the profile is a limiting factor