Facts about Thistle
- There are about 200 species of thistles, including Canada Thistle, Bull Thistle, Milk Thistle, and more.
- Some thistles, including Bull Thistle, is edible and can be roasted. Native Americans used to chew on the petals like chewing gum.
- Thistle seeds can stay viable for 20 years
- Thistle is used as a natural erosion control in nature
- The thistle is the oldest recorded National Flower, dating back to the 13th century in Scotland.
Ideal Conditions for Weed Growth
Thistle is found in both lawn, non-turf areas, as well as native areas. A healthy, dense lawn is the best defense against thistle, as it won’t grow well in shaded areas and by mowing tall, you will discourage the seeds and roots from growing up. Thistle prefers full sun, and clay soils, but will grow in many conditions. Weeds spread both by seed and rhizome activity.
How to Control Thistle
We have seen good results with our organic One Earth weed control, using back to back applications, about one week apart. This weed control is used in lawns, and is also an organic fertilizer. After the second application you should see the weeds turn brown or black and break down. Keep in mind that a single thistle plant can produce hundreds of feet of roots and additional stem shoots, making it difficult to control. Persistence and patience are key to controlling this weed.
Mulch is your friend in garden beds. Keep areas mulched to prevent the spread of thistle. Keep thistle mowed and prevent it from going to seed in order to reduce your thistle problem.
If you have a native area, we can apply a weed control called Milestone. This weed spray gets great control of thistle, with usually about a 90% control. It can take 2-3 applications for a major thistle problem. Below is a photo of mature Canada thistle.
Is this Thistle?
Knapweed has a flower that looks similiar to thistle. But the leaves look very different. This weed is also found growing in native areas. It can be controlled by Milestone. Below are photos of the leaves and flower or knapweed.
Prickly lettuce can be confused with thistle because of its serrated leaves. This will be controlled by our One Earth weed killer and fertilizer when found in the lawn.