People don't always know what they have in their yard. If somebody else put in most of the flowers and bushes in your landscaping, it's easy just to let them stay where they are. Trouble is, some plants that were popular in landscapes in the past are now recognized as being environmental problems. They spread fast and choke out native plants, reducing the food supply for birds and animals. Here are a few common ones, as well as tips on how to get rid of them.
These large bushes or small trees were introduced from Europe back in the 1840's for hedges and animal forage. With no natural enemies, the plants spread rapidly. They form large stands of bushes that green up sooner and stay green longer than native plants, so they choke them out. While buckthorn is illegal to buy in some states, it's sold in others. You can recognize Common or European Buckthorn by its black berries, grayish bark, and oval leaves with toothy ridges.
If you have buckthorn in your yard, make cuts in the trunk and spray them with a product such as Roundup® Poison Ivy Plus Tough Brush Killer.
You can replace your buckthorn with bushes that are friendly to birds and native plants. Chokeberry and Juneberry are good candidates and available at many garden centers.
These invaders from Europe first came over to North America as ship ballast and because they looked pretty in gardens. They long ago escaped their garden confines and now can be seen infesting wetlands, ditches, and streams all over the eastern US. Purple loosestrife stands from four to six feet tall with thin spikes of magenta flowers. Surprisingly, these plants are still sold in stores in many states. They're highly aggressive, and quickly dominate ecosystems, depriving wildlife of diverse food sources, and killing off native plants.
For purple loosestrife on dry ground, you can hand-pull it or spray it with a glysophate-containing herbicide, such as Roundup® Weed & Grass Killer. If you have some near a body of water, hand-pull them when they haven't yet produced seeds (one plant can produce 10,000 seeds).
Avoid buying cultivars of purple loosestrife, since even the so-called sterile ones can still pollinate their wild cousins. A better choice would be to plant blazing star, which has similar shape and coloring.
Honeysuckle bushes were introduced as garden plants as early as the 1700's. They didn't stay put. Nowadays, you often see Morrow, Armur, and Tartarian Honeysuckle Bushes in the wooded areas of city parks and roadsides. Spread by birds, they choke out lower-canopy trees, bushes, and flowers. You can recognize them by their oval leaves and small white flowers.
Since these bushes can just show up, thanks to birds, keep an eye out for baby bushes sprouting in your flower beds. Hand-pull the little ones, and treat the big ones with Roundup® Poison Ivy Plus Tough Brush Killer. Be sure to cover all the leaves, taking care not to spray the plants you like.
If you want a dense, pretty bush that feeds birds and produces flowers, chokeberry, inkberry, and serviceberry will do the job.
There are over 50,000 exotic plants that have been introduced to this country. Most of them stay quiet, but some, like kudzu, garlic mustard, and aquatic milfoil, can cause serious problems. You state's department of natural resources has information on the biggest problem plants in your area. Visit their web site to find out what you can do to help.