How to Cut Back or Kill Overgrown Blackberry Bushes
- 1). Put on protective clothing and eyewear before you tackle a large overgrown blackberry bush. This plant has sharp thorns that can do a lot of damage if you're not careful.
- 2). Cut back the blackberry canes at the ground. This can be challenging with a large, overgrown blackberry. Weed eaters, machetes and large mowers work. You can remove all or some of the plant depending on how much you want to take out.
- 3). Apply a herbicide when the new growth reaches 18 inches tall. Consult a landscaper licensed to apply chemical herbicides. Blackberries are tenacious and most of the stuff available to the home gardener won't do the job.
- 4). Remove all new growth as soon as it appears. Pull out small plants. For larger plants, dig down under the root and get as much as possible out of the soil.
- 5). Discard all cuttings. A piece of blackberry stem left on the ground can form new roots and grow into a whole new plant.