Help! Thistles are taking over the garden. #197997 - Ask Extension


Help! Thistles are taking over the garden. #197997

Asked July 09, 2014, 5:15 PM EDT

Help! Thistles are taking over the garden at my rental property. I have a particularly large patch (8x8) under a very large and beautiful weeping cherry tree. I read that I oculd apply a non selective herbicide to each plant but I dont want to kill off the tree. Any suggestions. I am losing the war. Every month I pull out at least one large black trash bag of 1.5 to 3 foot plants. they are amazing. I try to get them before they bloom.

Baltimore County Maryland

Expert Response

As you have found, thistles are pretty incredible for their ability to invade and withstand attempts to control them. Pulling them just makes them form a 'v' and come back twice. Over time you can tire them out, but not readily. Getting them before bloom is important to stop accumulations of future seeds.
You can carefully use a selective herbicide which will not harm your tree. You want to use a Round-Up-type herbicide with 51% concentration of the active ingredient listed as glyphosate. Mixing it with a sticker-type product like Turbo helps it to work. Glyphosate will negatively affect any green tissue it comes into contact with, so keep it away from desireable plants and your tree.
These plants are tough and you may need to re-treat. Always follow label instructions carefully.

Loading ...