Eradicating Goutweed

TheGardenLady received this comment from Susan:

My mother planted [Snow on the Mountain] 37 years ago. We bought her house 21 years and we are still trying to get rid of it. I am at my wits end!! But I have decided this year is gonna be the end of it! I have made it my personal challenge to finally see the end of it. I curse my mother every year when I see it. She thinks it’s funny. I however do not!! I cringe every time I’m in a garden center and see them selling it. It gives me anxiety. It must die!! Lol

It is interesting to this Garden Lady that so many of the plants that were brought to the US as ornamental or medicinal plants, have now
become invasive, noxious weeds. My lawn problem is ground ivy, glechoma hederacea, which was brought to the US as an ornamental or medicinal plant in the 1800s. It is interesting to me that it seemed to take so long for these plants to become pests. There is a long list of ornamental plants that have become invasive. Ornamental plants like Japanese and Chinese Wisteria wisteria floribunda and W sinensis, Callery Pear pyrus calleryana and Common periwinkle, Vinca minor are a few plants that have become invasive. Go here for some other invasive plants.

Your problem is Snow on the Mountain also called Goutweed or Bishop’s weed- Aegopodium podagraria. You are correct that this plant is difficult to eradicate. One has to get rid of all the root. To do it without chemicals, first remove your good plants from the area where you want to get rid of the Snow on the Mountain. Dig down 2 1/2 feet to get all the root. Put removed roots in the garbage, do not compost it. Then cover the dug area with black plastic and let sit fallow for 6 months. This should get rid of at least one area of the plant. See here.

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Invasive Lillies

2007.09.02 金針花 / 赤科山 / Day Lily by MaxChu

TheGardenLady received this question from Nikki.

I have seen orange sillies resembling tiger lilies growing wild. I think they might be day lilies. I am wondering if it is possible for day lilies to spread from from your garden and become wild lilies. Do you think it is possible for a garden variety plant to become wild?

Day lilies/Hemerocallis fulva, with the common names of common orange day lily, tiger lily, roadside ditch lily plus a few other common names, have become invasive in a number of states. (see here and here and for a map of where this lily grows, check out this site)

There are beautiful native lilies that you could grow that will not become invasive.

But if you are interested in growing day lilies, not all varieties are invasive according to the American Hemerocallis Society ‘s Information Release site about invasives. They say that, “Any of the thousands of commercially available hybrid day lily cultivars which are clump forming are said to not be invasive.”


Thompson & Morgan: An Excellent International Seed Catalog

bug of the day by urtica

Most catalogs have a limited area they can ship seeds or plants because of all the different countries’ rules and regulations regarding seeds and plant material coming into their country. In the United States some seeds or plants cannot even be shipped into certain states.

With all the international movement of people and things, countries fear invasive plants being brought in that will take over the native habitat or they worry about diseases or insects which, while being contained in the country of origin, destroy crops in their new “adopted” country. In the US we have many such problems caused by unwelcome pests coming in and it is a major economic problem. For example, one problem is an insect called the Asian Longhorned Beetle (see photo above) which came to the United states from China and is now decimating our hardwood trees like the Maple tree, the willow tree and the Elm tree (see here).

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More thoughts on getting rid of Yellow Sorrel (Oxalis Corniculata)

Yellow Sorrel (Oxalis Corniculata) by nickpix2009
Yellow Sorrel (Oxalis Corniculata) by nickpix2009

TheGardenLady received this comment on her post “Eradicating Oxalis Corniculata“.

This article does not do justice to the invasive and aggressive nature of Oxalis. If you try this what is described above you will FAIL (guaranteed).

If Oxalis has become such an invasive problem in your area of the country, you should call your county extension office to see what they recommend. Unfortunately there are weeds that are becoming extremely, agressively invasive and are becoming more and more difficult to eradicate safely or easily.

TheGardenLady always recommends the least toxic method of removal of both weeds and insect pests. Her parents were organic gardeners before, I think, the word even became popularized. We pulled all the weeds by hand and picked all the bugs off the plants by hand. I cannot recount the number of Colorado potato beetles I picked off the potato plants as a child or how many of the undersides of leaves I checked looking for the orange-yellow eggs to remove. Of course, potatoes were not our cash crop so it was doable.

My husband, who was a trained chemist, believed in organic methods of gardening. He knew how toxic some of those chemicals could be.

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Peppermint: The Invasive Herb

Peppermint by Jim-AR
Peppermint by Jim-AR

TheGardenLady received this question from Dan.

I have question about dead transplant. While transplanting some baby peppermint plants one of them got their tops broken off. I was wondering if the plant is technically dead or will it sprout new leaves around the base of the stem/root? The roots and stem is still strong 1 week later, but there are not leaves still.

Mints can be one of the most invasive herbs. Not only do they seem to multiply rapidly, they seem to send runners far from where they were planted. Peppermints are no exception. So even if you broke the tops while transplanting, if the roots are still healthy when you transplant it, the peppermint will send forth new tops.

One of the ways to propagate peppermint is from root cuttings. Spring is an especially good time for transplanting the peppermint when leaves are just emerging. New leaves will come out where the tops broke, be patient.  If anything, you will probably be sorry you didn’t kill it.

A good site on peppermint is this:

Top 10 Invasive Plants

In the last two posts (here and here) TheGardenLady explained the problem with invasive plants and how they came to the United States respectively.  In this post TheGardenLady will give a list of 10 of the invasive trees and shrubs in great parts of the US:

Tree of Heaven - Ailanthus altissima by maxi millipede (on flickr_
Tree of Heaven - Ailanthus altissima by maxi millipede

1. Tree of Heaven, Ailanthus altissima – This might be the tree in the fiction, “A Tree Grows in Brooklyn”

Japanese barnberry (Berberis thunbergii) by copepodo (on flickr)
Japanese barnberry (Berberis thunbergii) by copepodo (on flickr)

2. Japanese Barbery, Berberis thunbergii – landscapers love to sell this and plant this in your yard- be warned.

oriental bittersweet by ophis
oriental bittersweet by ophis

3. Asiatic Bittersweet, Celastrus orbiculatus – pretty in wreaths but don’t use it because when the berries spread, you are spreading this invasive.

Eleagnus umbellata_fruit.jpg by meghan.mcginty
Eleagnus umbellata_fruit.jpg by meghan.mcginty

4. Autumn Olive, Eleagnus umbellata – smells pretty, but what a nuisance.

Japanese Knotweed a real problem plant by arrowlakelass
Japanese Knotweed a real problem plant by arrowlakelass

5. Japanese knotweed, Polygonum cuspidatum – brought in as an ornament for screening and soil erosion.  Horrible.

brwyn, cyrs - Phragmites australis by Gwylan
brwyn, cyrs - Phragmites australis by Gwylan

6. Common Reed, Phragmites australis – This one may have come accidentally aboard a ship. It is now invasive in all but one state and is clogging up waterways.

Ampelopsis brevipedunculata, 蛇葡萄 sheputao, Porcelain-berry by pancrat
Ampelopsis brevipedunculata, 蛇葡萄 sheputao, Porcelain-berry by pancrat

7. Porcelain berry, Ampelopsis brevipedunculata – This plant is still sold by nurseries. Don’t buy it especially if you live in the eastern half of the US.

Lonicera japonica - Japanese Honeysuckle by mondomuse
Lonicera japonica - Japanese Honeysuckle by mondomuse

8. Japanese Honeysuckle Lonicera japonica, Tartarian Honeysuckle Lonicera tatarica and Amur Honeysuckle Lonicera maackii – 3 types of honeysuckle have become invasive.

 Pueraria montana var. lobata - Kudzu by johnstonephotos 	 Pueraria montana var. lobata - Kudzu by johnstonephotos
Pueraria montana var. lobata - Kudzu by johnstonephotos

9. Kudzu Vine, Pueraria montana var. lobata – This vine was brought to this country as an ornamental plant and as a forage crop and became so invasive- it has covered have the country.

Infiorescenza dell Acer platanoides.....Norway maple flowers by Sante.boschianpest
Infiorescenza dell' Acer platanoides.....Norway maple flowers by Sante.boschianpest

10. Norway Maple, Acer platanoides – This handsome tree was used for
landscaping. DON’T plant it. Nothing can grow under It.

How Invasive Plants Came Here

Glechoma hederacea - Hondsdraf, groundivy by AnneTanne (on flickr)
Glechoma hederacea - Hondsdraf, groundivy by AnneTanne (on flickr)

In the last post, TheGardenLady explained the problems caused by invasive plants – that is, plants that have come into the environment and take over the native plants’ environments, eventually choking out the native plants.  In this post, TheGardenLady explains how invasive plants came to this country.

Some invasive species came accidentally in ship ballast, packing materials or even on people who travel around the world and return with small seeds adhereing to shoes or clothes, etc.

Some came purposefully.

Some were brought as medicine or food. Ground ivy, Glechoma hederacea, with many common names one of them being Gill over the Ground, is an invasive that was brought here by our earliest settlers. Ground ivy has a long history of use in alternative medicine and as an edible herb, dating back to the first century A.D. Ground ivy was considered to be such a miracle medicine that it is said to be one of the first herb and edible plants brought to the North American continent. Now it has become so invasive that it is the bane of most people with lawns and there is not much one can do to get rid of it other than repeatedly plowing every tiny stem of the plant until it finally gets killed. But even saying that repeated plowing will kill the ground ivy may be wishful thinking because it sends out runners and may come to  our lawn from a neighbor’s.

Callery pear blossoms 1 by chasqui01 (on flickr)
Callery pear blossoms 1 by chasqui01 (on flickr)

Some were brought for horticultural use. The Callery pear was brought here from China and was used to decorate streets, parks and gardens. The thought was that the Callery pear would not fruit and was therefore sterile. They didn’t know that when the callery pear met other desirable pear species in this country, it wasn’t so sterile and started going forth and multiplying.  See here.

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The Problem of Invasive Plants

Leafy Scourge by Anita363 (on flickr)
Leafy Scourge by Anita363 (on flickr)

This May TheGardenLady attended a lecture called “Weeds in Nature’s Garden…the problem of invasive species” given by Bruce Barbour who is a Rutgers Cooperative Extension Environmental Agent. There are invasive plant species, invasive animal species and invasive disease species. This is a fascinating and scary topic. For example, the April 20th, 2009, New Yorker magazine wrote an article about the escape of exotic animals in Florida where they are now invasive species. We have all watched in horror as something called the swine flu or the H1N1 virus spread across the world.

But the invasive species that Bruce Barbour spoke about was the plants
species that have become invasive in NJ and around the country.

What are invasive plant species and why are they a problem? Well, the short answer is that these are plants have come into the environment some way and then they take over the native plants’ environments, eventually choking out the native plants and they become nuisance plants or weeds where they are not wanted. The native plants were the plants that fed the local animal population. Without the native plants to eat, the native animal, bird and beneficial insect populations that need special plants are lost or can become extinct. It is a vicious problem in at least the short and middle term. In the long term, millions of years from now, we can’t know what will happen.

If you’re concerned with the invasion of invasive plants, and you’re wondering about what types of plants your should plant in your area, there is an excellent website that talks about native plants for each area in the United States.  Here it is.

In addition, each state has its own Native Plant Society. Consider joining your state’s Native Plant Society or checking out their website.

In two days, TheGardenLady will continue to discuss invasive plants, in particular how they came to the United States.  So stay tuned.

Eradicating Oxalis Corniculata

Oxalis corniculata by (on flickr)
Oxalis corniculata by (on flickr)

TheGardenLady received this question from Gay.

What do you recommend to eradicate Oxalis in coastal climate (SF Bay area)? This is not the ornamental type, it is invasive with a succulent flower stem and yellow blossom.

Oxalis – Oxalis corniculata L. , yellow wood sorrel is an invasive plant in California.

This GardenLady always tries to first recommend the safest method of  weed removal, which is hand pulling. If you aren’t overwhelmed with too many Oxalis on your property always try hand pulling first. Now the problem with oxalis is that it has a long tap root. Besides these tap roots it also sends out stolons. A stolon is a shoot that bends to the ground or that grows horizontally above the ground and produces roots and shoots at the nodes. And it has rhizomes. A rhizome is a horizontal, usually underground stem that often sends out roots and shoots from its nodes. Plus Oxalis makes seeds. How is that for insuring species survival? So to eradicate the oxalis with all its alternative methods of growing into another plant, one has to get rid of all of its roots, stolons and rhizomes before it sets seed. That is very difficult to do. But one can try. If your soil is not rocky you can use a manual asparagus picker to get to the bottom of the tape root.  I hope you can still purchase these manual asparagus pickers. They have a handle and sort of look like a long screw driver with a V at the end which is what you use to cut. However,TheGardenLady does not know where to buy them. Mine is an antique from my parents’ farm.

Continue reading “Eradicating Oxalis Corniculata”

Identifying Invasive Species Workshop at the EARTH Center

                          Photo taken by urtica

One of the subjects TheGardenLady has been planning on writing about is invasive plants. Today she received this notice of a seminar at Rutgers on this very topic. If you are interested in learning how you can help in preventing foreign plants and insects from crowding out our natives, please contact the number below to see if you are eligible to attend.

On Saturday August 23rd, Middlesex County’s Extension Agricultural Office will be presenting a Garden Workshop from 10:00 AM to 1:00 PM at the EARTH Center in Davidson’s Mill Pond Park, South Brunswick. The workshop will be on “Invasive Species”, and how homeowners can do their part in helping prevent foreign plant & insect species from crowding out more desirable native species in their landscape. While some of the more nationally know invasive species include, the snakehead fish, fire ants, nutria, and kudzu, in the Northeast we have been impacted by organisms like the Asian Longhorned Beetle and the Hemlock Wooly Adelgid.

This workshop will be hosted by Bruce Barbour, Environmental Program leader for Rutgers Cooperative  Extension of Morris County. Coming from graduate schooling in weed science he served as Chair of the Department of Agriculture & Resource Management Agents at Cook College and serves on two committees of the NJ Invasive Species Council.

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