Get rid of overgrown or invasive shrubs to remove brush and allow air and light to get to plants and lawns. Clear out brushy shrubs to deny shelter to rodents and insects. Remove old shrubs that have ceased blooming or haven't responded to hard pruning and rejuvenation. Depending on the shrub's growth habits, it can be removed using mechanical, chemical or a combination of the methods. Follow up any removal strategy with cultivation and treatment against suckering for invasive or aggressive growers.
Dig small shrubs out by forcing a sharp garden spade into the soil around the shrub's outer dimensions. Work in toward the shrub's center with the spade or a garden fork, cultivating the soil until you can pull the whole shrub out of the soil.
Cut larger shrubs down and chop trunks below ground level with a hand axe or grinder. Cutting below the surface denies the roots the chemicals that are produced by photosynthesis that make food for the plant. Cover the stumps with soil. You can plant new shrubs a few feet from the old stumps if you cut the roots with a sharp garden spade and cultivate the area thoroughly.
Use contact herbicides formulated for use on woody or herbaceous shrubs that contain glycophosate or triclopyr. Check the label before using any herbicide to make sure that your shrub is indicated as a species upon which the herbicide is effective. Always follow directions for mixing and use. Brush killers should work in two to six weeks. Clean out dead shrubs and do not replant the area until the herbicide has had time to dissipate, a period that should be noted on the label.
Stop suckering on shrubs like lilac, hawthorn and dogwood by painting herbicide containing chloflurecol-methyl or naphthalene acetic acid to the open ends of cut stems. Apply these growth regulators to keep underground roots from suckering. As with any herbicide, check for indicated species and follow application directions.
Clean out brush, cut branches, wood chips and dead leaves completely. Woody material left to decompose is free to root and form new plants; it also provides a home for fungus, disease and critters. Chop and compost clean, uninfected shrub refuse for use in the garden as mulch.