Landscaping can add value to a home.
Choosing plants that can be maintained and sustained can make a big difference in a landscape. Yet ease of care should not be your only consideration. Sometimes a plant can grow too well, become a nuisance, and begin to invade other areas of the yard, the neighborhood and natural areas. Most invasive plants that take over were started with good intentions. By definition, an invasive plant grows aggressively and spreads quickly, outmatching other plants and causing harm to natural areas. Invasive plants are capable of surviving and reproducing rapidly outside of cultivation. Most invasive plants are non-natives that originated in other parts of the world. About 85 percent of the invasive species in the United States were introduced for ornamental or landscape use. Second to land-clearing, invasive nonnative plants are considered the biggest threat to native species. An example is kudzu, which engulfs many areas of the country. This noxious, fast-growing vine was introduced for erosion control. It worked, but it didn’t stop where it was planted. Today it is estimated that seven million acres in the United States are covered in kudzu. Other invasive plants include Japanese honeysuckle, privet and bamboo; these also were intentionally planted, and some still are.
Does that mean that you should only plant native species ? No. While native plants grow well and are excellent choices in our landscapes, there are many other landscape plants that thrive without taking over. There are even some natives which may get aggressive under certain conditions. Consider the free-flowing nature of Carolina jasmine (Gelsemium sempervirens ). Native to the southeastern United States, it can spread, as can devil’s walking stick (Aralia spinosa ), another native with wicked thorns.
Most landscapes have numerous invasive or nuisance plants in them. Japanese wisteria is gorgeous in the spring when in bloom, but it can easily get out of hand if not pruned and trained to a trellis. Allowing it to grow in trees can lead to the death of the tree, from girdling of the trunks and adding weight to the limbs. Same thing for English ivy. It quickly spreads on the ground, covering up other plants in its path, and will also grow up trees. While it usually won’t girdle the trunk, if left unchecked it can cover tree limbs, adding too much weight and competing with the tree’s foliage for sunlight. There are several groundcovers that work well in a landscape to cover quickly, then begin to spread everywhere. Consider Vinca major, Liriope spicata and Wintercreeper euonymus (Euonymus fortunei ). All are vigorous growers and can be found in many parks and woodland areas surrounding neighborhoods. Vinca minor, which has smaller leaves, is not as vigorous, and variegated forms of these plants usually aren’t as bad as the green-leafed forms. When choosing monkey grass or liriope, choose the clumping form (Liriope muscarii ) and leave the running form (L. spicata ) behind. Running monkey grass can easily overtake a garden.
Other groundcovers that have been known to spread under ideal conditions include chameleon plant (Houttuynia cordata ), bugleweed (Ajuga reptans ), deadnettle (Lamium species ), and ardesia. Bamboo is commonly used as a screen or hedge. Avoid using the running forms. Clumping bamboo can stay in place, while running bamboo spreads prolifically and is almost impossible to kill. Yet people continue to plant new bamboo on a regular basis. The American Bamboo Society on its Web site (www. american bamboo. org ) expounds on the attributes of how fast and tall it grows: “David Farrelly, in... The Book of Bamboo, says that bamboo has been measured to grow 47. 6 inches in a 24-hour period.... What’s most remarkable is that 8-inch diameter 60- to 80-foottall bamboos have reached that height in one growing season.” And people think that is a good thing ? While you may want instant screening, what happens five years down the road, when your neighbors are being invaded and you want it to stop ?
Other common landscape plants that might be found when taking a hike in the woods include nandina, Chinese photinia, bittersweet, and mimosa trees. Monitor natural areas and try to notice the spread of landscape plants. Most invasives usually have viable seeds, which birds eat then drop and new plants emerge. Nandinas can be great landscape plants, but they can spread. Privet is a common hedge in landscapes. If you can keep it pruned and prevent it from blooming and setting seeds, it can be kept in check. If allowed to set thousands of black seeds, privet will be a common occurrence throughout your yard and surrounding areas. The Bradford pear has created a real nuisance in many open areas in the state. The seedling Callery pear resulting from their fruit has created colonies that are taking over. Other weedy trees include tree of heaven (Ailanthus altissima ), royal paulownia (Paulownia tomentosa ) and popcorn tree (Sapium sebiferum ).
Not all parts of the country have the same problems with the same plants. Climatic conditions, soil types, and amounts of rainfall all play a part. In the northeastern United States the big invasives are barberry, buddleia (butterfly bush ) and burning bush euonymus, which have not posed a threat in Arkansas. In Arkansas, the top 10 threats are privet, English ivy, Japanese honeysuckle, Vinca major, Bradford pear (Callery seedlings ), Japanese wisteria, bamboo, kudzu, mimosa and nandina. But they aren’t the only problems. Some euonymus plants, mints, spiderwort and obedient plant can get aggressive. The type of care these plants get also can make the spread worse. In dry conditions, some plants may not spread as quickly as in moist, highly fertile areas. Some plants have become so noxious that the planting of them has been banned in Arkansas. These include purple loosestrife (Lythrum salicaria ), water hyacinth, giant salvinia (a water fern ), and Japanese blood grass.
One other thought to ponder is the introduction of new species. We haven’t grown them long enough to know how well they will thrive in our areas, and there is a possibility we may be planting potential problems. We especially like plants that grow quickly and take care of themselves, but some may get too comfortable and start to spread. Recent introductions that we are now recognizing as troublesome include limelight artemisia, the tall Mexican petunia (Ruellia tweediana ), crocosmia and hydrilla (a water plant ).
Invasive plants produce large numbers of new plants each year, multiply rapidly, are tolerant of a wide range of conditions and are spread easily by wind, water or animals. Choose your landscape plants wisely. Coming next week So you think you can install a laminate floor ? See what it’s like as described by our staff do-it-yourselfer Randal Hunhoff.
FEEDBACK:
Something to say about this topic? Submit a Letter to the Editor online
