Aggressive plants can take over even the most meticulous garden. Perhaps you planted a tendril of gooseneck loosestrife and regret it, or your neighbor’s periwinkle is creeping into your rose garden.
No matter how attractive they are, aggressive plants can be hard to control because, by nature, they are quick to spread and difficult to kill.
Read on for tips on how to control aggressive plants that are trying to take over your yard or garden.
Mechanical Control of Aggressive Plants
Mechanical control is a fancy way of saying dig them up! Though it can require hard physical work, mechanical control is the best way to get rid of aggressive plants that are taking over where they aren’t invited.
Since your back may not agree with this advice, follow these tips to keep digging to a minimum:
- Use a Fork: Many invasive plants spread by underground roots. A regular shovel slices right through the roots, leaving pieces of root behind to sprout and spread. If you use a cultivating fork, instead of a shovel, to loosen the soil and gently pull out all those pesky roots, you’ll have a better chance of getting them all.
- Till with Care: You may be tempted to pull out your garden tiller and just plow up the whole area. If you do this, be sure to sift through the soil and pull out all the traces of roots and shoots. Many aggressive plants thrive on disturbance, so simply tilling won’t get the job done.
- Dig in Soft Soil: Do your digging in spring or early summer, or after a good soaking rain, so the soil will be soft and roots will slip out easily instead of breaking off.
- Mowing: Repeated mowing may eventually kill off unwanted plants, if you mow off all the leaves and keep them mowed so the plant can’t photosynthesize. Mowing can take months or even years to work, because at first the plants respond by bushing out even thicker, so you have to keep at it and eventually force the plants to use up all their root reserves.
Chemical Control of Aggressive Plants
Chemical control with herbicide sprays, can be a good back-up if digging isn’t working; or if you have an isolated patch that can be sprayed without affecting other plants.
Follow these tips when using chemical herbicides in your yard or garden:
- Herbicides: There are two main herbicides that seem to work with aggressive plants: glyphosate (Roundup) and triclopyr (Brush-B-Gone).
- Timing: For best results, spray when plants are actively growing and flowering.
- Mow First: Some research has shown that sprays work better if you first mow or cut the plant down, wait for it to sprout again, and then spray the sprouts. This can be a great strategy, because if the cutting or mowing works, you can avoid spraying altogether.
- Avoid Wetlands: Most states require a permit before spraying anything in or near wetlands because of the risk of pollution and harm to amphibians.
- Apply Carefully: Spray the herbicide directly on the plant’s leaves, being careful not to spray the ground or other plants. Alternatively, you can paint the product on the leaves or, for shrubby plants, cut them down and paint concentrated herbicide on the cut stem.
- Minimize Waste: To keep track of which plants you’ve treated, add a bit of food coloring or biodegradable fabric dye to the spray mixture.
Disposing of Aggressive Plants
Once you’ve pulled, dug, or killed unwanted aggressive plants, be sure to dispose of them properly so they won’t find their way back into your yard!
Here are some tips on how to dispose of aggressive plants:
- Burn: Either burn the waste yourself, or drop it off at your local landfill – they often have a burn pile.
- Compost: If the plant is very aggressive, don’t add it to your compost pile unless you’re confident the pile will generate enough heat to kill the roots and seeds. However, you can create a separate out-of-the-way compost pile for aggressive plants, as long as you don’t use the compost from it in your garden.
- Sun: Spread the pulled plants out on a driveway or patio, and let them bake in the sun until they’re good and crispy. Then, throw them away.
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