Canada thistle is resolute in its efforts to maintain its reputation as one of the most hated weeds home gardeners must face.

Pull it out by the roots, spray it, dig it out — I've tried all methods. It returns, amazingly in the same place I thought I was rid of it last year.

Canada thistle (Cirsium arvense) is a perennial with green, deeply lobed, spear-like leaves and sharp barbs. The flower is a purple pom-pom topping the plant.

If allowed to go to seed, the flower turns into a puffy white cloud, resembling a dandelion seed head.

Flowering occurs from June through October. The flowers are pollinated usually by wind but also by insects attracted to the weed's strong honey scent.

Flower heads produce up to 50 seeds and the average stem has 12 to 14 flowers.

Despite its name, Canada thistle is not native to the North American continent. Europeans brought it, possibly with contaminated crop seed, in the 17th century.

It spreads rapidly, crowding out native, agricultural and desirable plants. The bristles can easily irritate the skin.

Is there any good news?

Yes, Canada thistle is a great pollen plant for the honey industry. It's a food plant for the caterpillars of the Painted Lady butterfly. Even so, I don't want it in my yard.

Why is it so hard to eliminate?

Canada thistle has an extensive root system that spreads up to 17 feet horizontally and 20 feet deep. The plant can grow back from even a tiny part of the root left alive in the soil.

Because of this, plan your strategy and count on a long battle if you want to get rid of this weed.

What's your first course of action?

As Canada thistle seems to thrive in low fertility soil, consider improving your soil to make your garden and lawn less welcoming. A soil test kit, available from the Penn State Extension Office, is a good place to start.

The test results will tell you what nutrients you need to improve your soil.

Home gardeners can spray Canada thistle with 2, 4-D or glyphosate. To avoid damage to desirable nearby plants, use a paint brush to apply the herbicide to just the thistle.

For organic control, snip off the plant at the base with scissors. Then check the area weekly, snipping off any new plant growth you find.

If you have a small infested area, lay plastic or several layers of newspaper over it — making sure the paper or plastic is anchored down with stones or bricks and that there are no openings between paper or plastic sheets because the plant will make its way through the tiniest opening.

The key to success in all these methods is to be consistent and watchful.

If you see new growth, cut it off or reapply herbicide.

The goal is to force the plant to exhaust its energy reserves and give up.

It's not easy but you'll reap the rewards of your efforts when your garden is free from Canada thistle.

Call the Master Gardener Greenline at 724-287-4761 Ext 229, with your questions about Canada thistle and other weeds.