General Discussion:

Invasive perrenials

Messages posted to thread:

Keith23-Jun-02 10:32 AM EST 5b   
Susan23-Jun-02 12:55 PM EST 6a   
23-Jun-02 06:50 PM EST   
23-Jun-02 06:54 PM EST   
Grace23-Jun-02 07:40 PM EST 2b   
leh24-Jun-02 01:35 PM EST 2b   
Betty24-Jun-02 08:58 PM EST 5a   
Grace24-Jun-02 10:28 PM EST 2b   
Glen - Regina SK25-Jun-02 07:33 AM EST 3   
jak25-Jun-02 10:01 AM EST 4   
Grace25-Jun-02 12:13 PM EST 2b   
Glen - Regina, SK25-Jun-02 03:40 PM EST 3   
Julie K26-Jun-02 01:32 PM EST 3b   
Lyn13-Aug-02 10:36 PM EST 3a   
Susan14-Aug-02 08:28 AM EST 6a   
Ann14-Aug-02 07:42 PM EST 4b   
Lyn14-Aug-02 10:37 PM EST 3a   

Subject: Invasive perrenials
From: Keith
Zone: 5b
Date: 23-Jun-02 10:32 AM EST

I have recently created a large shrub/flower bed in my back yard. It ranges from partial shade to full sun. A friend has given me several perrenials to put in the bed, many of which I am unfamiliar and some which we cannot identify. From my research on the ones we can identify I believe some are invasive. For example we have gooseneck, ajuga, vinca minor,lily-of-the valley and forget-me-nots. The internet seems to be full of horror stories with some of these plants, particularly with them spreading into a lawn and choking off other plants. Can anyone tell me just how much of a real problem these plants can be and whether this is a high maintenance issue. Thanks

Subject: RE: Invasive perrenials
From: Susan
Zone: 6a
Date: 23-Jun-02 12:55 PM EST

Gooseneck loosestrife is definitely a problem - rapidly creeping underground stems and seeds itself. The flowers are pretty but you will regret it if you plant it in your garden! Ajuga is also a spreader and will spread into the lawn. In the garden it is not too bad to remove but can be difficult in the lawn. If you have a damp, shady area where you don't mind it spreading (e.g behind a garden shed...?), then it has a place. There are non-spreading types but they're hard to find so, odds are, you're got a spreader. Vinca minor is a spreader but slower than the others. Once it roots itself as it spreads, it can be very hard to remove. But the flowers are pretty and the evergreen foliage is nice. It grows well in difficult conditions - good for under evergreens but not in your flowerbeds.... Lily-of-the-Valley is also a fast spreader by underground stems and is definitely not for the flowerbed. It does well, and will be less of a problem, if you plant it somewhere like between the foundation of the house and a concrete walkway. It will smother out any other perennial you try to grow with it. We had a nice area of it along the garage at our previous house - there was euonymus climing the wall, Liliy-of-the valley in a 18" wide swath and then a concrete walkway at the top of a ditch between our garage and the neighbour's. Nothing much else would grow there; the liy-of-the-valley provided heavenly scent and flowers in May; the walkway, foundation and ditch kept it in bounds. Forget-me-nots are a different sort of 'problem' - they self-seed freely and will pop up everywhere. They are beautiful in flower though and make good fillers around other plants. After the flowers fade, the plants get very scruffy-looking. The simple thing to do is - let them flower then rip out the plants as soon as they start looking scruffy. They will have set enough seed so that you will have some more next year but you will have prevented them from going totally nuts re seeding themselves. There's always a place for forget-me-nots in the garden! If you like the flowere but don't want to be bothered by the ripping out process, get yourself some brunnera macrophylla - flowers are almost exactly the same but doesn't have the seeding problem, plus you get the bonus of leaves that end up looking something like a hosta. They're fabulous plants....

Subject: RE: Invasive perrenials
Date: 23-Jun-02 06:50 PM EST

Friends are usually well meaning when they share plants.

Which plants however, do they often have lots to share?

The ones that have spread all over their own garden.

Here's some other high maintenance spreaders - Campanula puncata, Campanula takesimana, any Lysimachia, Artemisa ludovicina (Wormwood/Sage), Physostegia virginiana, (Obedient Plant), Beebalm (Mondarda spp.) and two to be avoided at all costs (you've been warned!) Goutweed (Aegopodium podagaria 'Variegatum'), and Campanula rapunculoides (Creeping Bellflower)

Subject: RE: Invasive perrenials
Date: 23-Jun-02 06:54 PM EST

Excuse my bad spelling - make that Campanula punctata, Campanula takesimana, any Lysimachia, Artemisia ludoviciana (Wormwood/Sage), Physostegia virginiana, (Obedient Plant), Beebalm (Monarda spp.) and two to be avoided at all costs (you've been warned!) Goutweed (Aegopodium podagraria 'Variegatum'), and Campanula rapunculoides (Creeping Bellflower)

Subject: RE: Invasive perrenials
From: Grace
Zone: 2b
Date: 23-Jun-02 07:40 PM EST

Another one that spreads more and more every year is yarrow. And OH...they are hard to yank out!

Subject: RE: Invasive perrenials
From: leh
Zone: 2b
Date: 24-Jun-02 01:35 PM EST

To the person who submitted just before Grace, thanks for the great info. Would you give us your zone please. I know plants act differently here in zone 2b (i.e. virginia creaper here is well behaved while in BC (garden heaven), it's a weed). Sometimes the area makes a difference on how "bad" a plant is.

Grace, you must be too nice to your yarrow. I stuck mine in a dry dry dry spot under maples (I know, plant abuse!!!) but it's behaving quite well.

Subject: RE: Invasive perrenials
From: Betty
Zone: 5a
Date: 24-Jun-02 08:58 PM EST

I have several of those invasive plants you mention that behave quite nicely in my garden. I find everything (except goutweed, which nothing slows down) behaves according to your soil, your zone, and the moisture level. I grew Gooseneck loosestrife for 5 years and it never spread, I moved it to another bed with different conditions and it has spread but still not what I would call invasive. I use vinca but would never place in a flowerbed. I use it for slopes that are difficult to mow and in contained areas. You are wise to check all plants carefully before planting in a large bed. If in doubt, plant in a holding area and observe how it grows for at least one year. If not rampant, transplant to a larger bed. If it is, remove and dispose.

Subject: RE: Invasive perrenials
From: Grace
Zone: 2b
Date: 24-Jun-02 10:28 PM EST

leh, I have my yarrow on the south side of my home up beside the house. It must like the sun. I started out with just one plant, given to me by a friend, and it just got bigger every year...2 ft by about 4 ft. I had my nephew dig some of it out this year, so it doesn't lean over my sidewalk. It has pink flowers.

Subject: RE: Invasive perrenials
From: Glen - Regina SK
Zone: 3
Date: 25-Jun-02 07:33 AM EST

leh - Sorry, I don't post here much, when I do, I usually forget to put in my name. All the ones I mentioned I grow in pots sunk into the ground to act as a 'jail' to keep their rhizomes from spreading all over. In addition, I throughly deadhead C. punctata and C. takesimana because they're heavy self-seeders too (if wife didn't like these two, I'd turf 'em, sheesh they manage to spread no matter what I do).

Be careful of some ornamental grasses, too. Skinner's Golden Brome, and Ribbon Grass like to spread all over.

I'm into Sask. native plants (grow 40 species), several have been a real nuisance - Gumbo Primrose (Oenothera caespitosa) spread all thru my rock garden. After much work now grow only in pot sunk into garden. Same with Scarlet Mallow. Native Milkweed (Asclepias speciosa) is great for attracting Monarchs in the yard but spreads all over because of its roots, had to resort to Roundup (which I haven't used in years) to knock it down last year... is back again this year Pink Corydalis (Corydalis sempervirens) I refuse to grow anymore because of its incredible heavy self-seeding.

Goutweed and Creeping Bellflower are plants from hell. I'm not the smartest guy around, but I know better than to plant these two.

Regina used to be zone 3a/2b, now is classified 2a which is nonsense for perennials, but the new zones I think are based more on woody plants than herbaceous ones.

Subject: RE: Invasive perrenials
From: jak
Zone: 4
Date: 25-Jun-02 10:01 AM EST

Hi everyone. I have almost all of the plants noted above in a large shady bed around a patio which has a huge norway maple in the middle of it. These groundcovers are just the thing for me. They cover all of the available space. When I want to plant something in my garden, and I have many, many perennials, I simply rip out a space for the newcomer and put it in leaving a couple of inches bare around the new acquisition. Every week I go out and tear back anything that encroaches on the "real" plants. True enough, they really spread, but I literally never have to weed that bed and it is very large. People walk into this shady nook and find it amazing lush, it looks like a woodland. Even the goutweed, contained by the patio, works. Depends on what you want to do. I agree that the best advice is to research first so you know what you are getting into!

Subject: RE: Invasive perrenials
From: Grace
Zone: 2b
Date: 25-Jun-02 12:13 PM EST

Oh, scarlet THAT sounds like something I'd like. Does it grow several feet tall and is covered with blooms right up until freeze-up? I have a mallow that grows about 6 ft. Mine is pink, and gorgeous in the summer I'd love to get some scarlet=flowered ones.

Subject: RE: Invasive perrenials
From: Glen - Regina, SK
Zone: 3
Date: 25-Jun-02 03:40 PM EST

Grace - I grow tame Mallows, too, large bushy plants all.

Scarlet Mallow (Sphaeralcea coccinea) however, is a tiny gaffer, well suited to the rock garden.

Plant has greyish foliage, creeps along the ground and has showy bright reddish-orange flowers. Good xeric plant, this grows in the wild in very dry prairie grassland.

I have photos at the link below. Got mine from a wildflower nursery, or maybe from a friend who sells native plants as a small sideline here in Regina. Besides being invasive in rich soil (my rock garden soil is way too rich, darn), the plant is difficult from seed, you may not find its seed offered for sale in any catalogue.

The genus Sphaeralcea is in the Mallow family and includes taller, upright species native to Western US. The other couple of species I've seen also have greyish foliage and orange flowers.

Subject: RE: Invasive perrenials
From: Julie K
Zone: 3b
Date: 26-Jun-02 01:32 PM EST

Also don't forget sweet woodruff. It is very lovely in my northern raised bed, but it is trying to grow under the bed onto the grass (as is the goutweed). I just rip them both out when they get too bad.

Subject: RE: Invasive perrenials
From: Lyn
Zone: 3a
Date: 13-Aug-02 10:36 PM EST

Now that I have Lily of the Valley running rampant how do I get rid of it? I've tried Round-up but it doesn't seem to do much. I'm slowly digging it out but I can't possibly get all of the roots so HELP!!!!

Subject: RE: Invasive perrenials
From: Susan
Zone: 6a
Date: 14-Aug-02 08:28 AM EST

Lynn - re Lily of the Valley - I've been battling some of that since we moved to our current house three years ago. I dug out the largest clumps and put them in places where I didn't care if they spread (behind the shed; behind the garage....) For the remnants, I just pull out any leaves that appear as soon as I see them. There are fewer and fewer of them so I think I'm gradually wearing them down! Spring is when you have to be particularly watchful for survivors. I haven't seen any new growth for the last two months....

Subject: RE: Invasive perrenials
From: Ann
Zone: 4b
Date: 14-Aug-02 07:42 PM EST

For Roundup to work really well, the plant you treat should be ACTIVELY growing, so early Spring is a good time. I am thinking of planting all of the most invasive plants in patches of Dog Strangling vine !! (Vincitoxicum Nigrum) We are getting inundated by it and nothing we have tried so far has killed it. Not even three applications of Roundup. I am finding it in every single bed, shrub and around trees.....HELLLPPPP.

Subject: RE: Invasive perrenials
From: Lyn
Zone: 3a
Date: 14-Aug-02 10:37 PM EST

Ann - I found a site about invasive perennials and found out that for your dog strangling vine (Cynanchum nigrum)and my lily of the valley we just have to keep digging. There is no easy solution.

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