Gardens Gone Bad: Are You Growing One Of The World's Most Invasive Species?

It's purple, it's beautiful, and it has now reached every single state in the country except for Florida. It's purple loosestrife, ranking it at number 50 on the Global Invasive Species Database's list of most invasive alien species in the world. While many states have outlawed the sale and planting of this noxious weed, it can still be purchased online from states that have yet to do so. Also, its availability makes it a favorite mix-in for wildflower seed packets in states where it's legal, so you may have bought and spread this problem-plant around your property without even realizing it.

How Do You Know If You Have Purple Loosestrife?

This weed is most easily identifiable in June through August when its tall, woody, square stalks are decorated with bundles of tiny yellow-centered purple flowers. The flowers each have 5-6 petals and the leaves are smooth-edged and covered in tiny hairs. The plant favors moist soil with full sun to partial shade. 

You Know What Loosestrife Is, But It's Pretty And You Want To Keep It

Purple loosestrife is absolutely an attractive plant. In fact, it's almost breathtaking to drive down a country road mid-summer and see the bright purple meadows that have been overtaken by the weed. Below that pretty appearance, though, purple loosestrife is choking out native plant species and depleting the food sources of some birds, fish, mammals, amphibians, and insects.

The plant came to the United States from Eastern settlers in the early 1800s. Some of it was dragged accidentally on ships, and some of it was purposefully imported for use in gardens and in some medications. So, how did things get out of hand? Each purple loosestrife plant drops 3 million seeds in its lifetime and the seeds have an unheard of 100% germination rate. These facts, coupled with loosestrife having few natural predators in North America quickly led to an all-out purple plant pandemic that is still raging today.

This plant does far more harm than good, and you do not want to keep it in your garden.

You Have A Small Amount Of Purple Loosestrife And It's Contained

If you have purple loosestrife contained in your garden, it won't be contained for long. The seeds are small enough to be carried by the wind, and also travel by way of rainwater and by attaching themselves to animals, insects, or even your clothing. You've got to dig up the plants and dispose of them correctly before they can send those millions of seeds out to set up new camps.

If you're attacking your loosestrife in early summer before the flowers have gone to seed, simply dig up the plants, paying close attention to extract all of the roots from the soil. Burn the plants yourself or take them to your local waste management facility for incineration. Composting is not an appropriate means of destroying the plants as the seeds can survive the process.

If your loosestrife has gone to seed, place a large paper bag over the top of the plant, bend the stem downwards, and then cut the flowering part of the plant off to fall into the bag. You may then dig the plant up without worry about it dropping seeds before incinerating the loosestrife yourself or taking it to your local waste management facility.

Your Loosestrife Has Broken Free From Containment And Is Taking Over Your Property

If your purple loosestrife broke free from containment long ago and is well on its way to ruling your property, it may be necessary to attack it with biological warfare in the form of beetles and weevils.

Between 1987 and 1991, America worked with Europe to test over 100 bugs that were considered predators of purple loosestrife. Of those 100 bugs, 4 heroes emerged  -- 2 leaf-eating beetle species, a root-loving weevil species, and a flower-munching weevil.

All of these loosestrife predators are selective killers, meaning they attack the loosestrife and leave the native plant species alone. While any one of these bug species will help to slow the spread of purple loosestrife on your property, a combination of the species provides the most effective control.

The leaf-eating beetles are easy to obtain -- you can purchase them online or from your local weed control service. The root and flower eating weevils are a bit more difficult to find. Contact your local Department of Agriculture; they may be in cooperation with an already-established weevil program close to you. Oftentimes, these programs will offer you a few weevils and show you how to breed  them in containment until you have enough to release. 

Purple loosestrife is a highly-invasive plant that is dangerous to native ecosystems. Never grow this plant on purpose, and read your seed packets before you use them to prevent accidental loosestrife planting. If you've happened upon this information too late and you've already got the weed on your property, follow the above advice for managing it and contact a weed control service if you need further assistance and continue to discover more here.