Thursday, August 6, 2009

Invasive Plants I Wished Didn't Come With My Garden

Most Gardeners in America don't start a garden from scratch, aside they build their own house or buy a house where nobody gardened before, you get a house with an garden which already is very much established or might not be to your liking.
Luckily Gardens are changeable, sometimes it's an easy job. Tear out some plants here and there, move things around, add some more. If the previous caretakers of this garden did a great job, then it's possible to work with what they have left behind. It's another story if the previous gardeners had no clue what they were doing, or were the lazy type of gardeners, who planted easy things, things which you plant once and soon they cover half your yard, or they could have left you a yard so tacky you barely can stand sitting in it.
After all isn't Beauty in the eye of the beholder?

So most true gardeners want to make the garden they get their own.

It is always a good idea to at least wait a season after moving in to watch what will pop up in the yard. There could be some pleasant surprised in the new yard, plant treasures and wouldn't it be a shame to accidentally killing some plants you would have enjoyed because you didn't wait before digging in.

Sometimes plants come with a new yard, you wished you would not have waited. All of a sudden they start popping up all over the garden, or start spreading in a tick mass covering everything up what gets in their way. You see these plants and wonder, "Why do I see these plants all of a sudden pop up all over the yard? Where did they come from? I didn't see them when we first got the house."
The reason they are all over your yard now, are: the previous owner planted some plants, they must have known about it's invasive potential, so they cut off the seed heads just in time and they never put any of these plants into the compost pile, they knew what would happen if they didn't keep them out of there.
You, unfortunately waited a year to not accidentally kill something you might enjoy, you just sat back and watched the garden grow and bloom and seed out. You also, as the winter approached, cut some plants back, uncovered some poor plants from this ever spreading ground cover and tried to compost it, now every little sprig of this plant survived the compost pile and after spreading your compost around your garden you spread the little, harmless looking plant all over the yard.
After you realize what has happened you think to yourself "I should have identified this plant and read up on it" but it is too late now. It is everywhere and no matter how hard and often you weed, it is uncontrollable. It has become the bane of your garden.

Has that happened to you? I bet you also had some not to nice thoughts about your previous garden care takers.

So I like to share some of the plants I wished I would not have in my garden. Plants which came with my garden and I probably spread accidentally or are just so invasive that I will never get rid of them. Believe me, I tried, I am at my 7th year in this garden. I am ready to give up on them. These plants keep me so busy that they keep me from doing the garden work I enjoy so much. Who wants to weed all the time, especially knowing you will never be able to control them.

Beware of these Plants:

Sagina subulata
Picture can be found here

very often sold as 'Scotch Moss' although it really is the 'Irish Moss'
Scotch Moss's botanical name is: 'Arenaria verna' it looks almost the same then Irish Moss, it has the same tiny flowers but it has a yellow tinge to the foliage, while the Irish Moss is darker green. Neither are really a 'Moss' but are used to give a moss like structure to the garden, they also grow where you wouldn't or couldn't grow real Moss.
In some areas gardeners have a hard time keeping it going but if you give it just the right climate and growing areas it just will go berserk.
Unfortunately Western Oregon just has the perfect climate for it. It should not be sold to unsuspecting gardeners or at least have a warning label of this kind : 'Plant this ground cover on your property with caution, since it is very invasive. It can regrow even from the smallest bit of green, worse if can and will reseed itself.'
It does not have a deep root system but I found the root system is like a dense mat, so even it pulls out easily you never get it all. Also you constantly pull up the top layer of your dirt. There goes all your good garden soil into the yard waste bin. Because you never want to put it into the compost pile. It will not be killed. In fact I put all the pulled up plants, dirt and all into a thick, dark plastic garbage bag and left it in a sunny spot for a year, thinking it will all be killed. When I opened it, it actually still had some living plants in there.
I even found this plant growing along streets in town, between cracks in the paving, in the forests and wild areas around town, the seeds and probably also pieces of the plant stick to your shoes and get spread around.

Soleirolia soleirolii
see picture here:

also called 'Mind your own Business', 'Mother of Thousands', Baby Tears (what fitting names) and others it likes to grow in any moist soil in sun or partial shade. It's highly invasive and difficult to eradicate. Even the roots are very invasive, the tiniest sections of stem will re-root where it is happy. Every piece of plant has the potential of making more plants. Plant pieces brake off easy, so it's a piece of cake to spread it by carrying pieces around on your shoes or clothing. As I hear it is not finicky about the soil, it likes them all as long it has moisture. About moisture, even if you let it all dry outs and it looks dead (you think, finally it's dead) wish again, as soon the rain starts it comes alive again. The roots keep it alive for just long enough. Same with winter, it dies back just to come back in Spring, leaping a few more yards.
Mine grows all over the Rock-walls in my garden. The previous owners must have liked the way it spills over the rocks. This means, because there is no way I can dig all the roots out between the Rock-walls, aside of disassemble the walls. I read the only way to get rid off it is to strip off the infested beds, removing all roots and stems and do not dare compost it.
Selective weedkillers won't work either, you have to dig all the plants up you want to keep, making sure no piece of Baby Tears is left on your plants, then kill whatever is left in that area and replant. There is no way I can get rid of it, at this point all I can do is trying to keep it in check every year I see it in new spots.
As I read on the internet this plant is on the invasive plant list in many countries. It should be outlawed to be sold to unsuspecting customers.

Glechoma hederacea also called creeping Charlie, ground ivy, gill-on-the-ground, creeping Jenny
see picture here:
its part of the Mint family and everyone who knows Mint, knows how fast it can spread. This plant spreads just like Mint by seeds, rhizomes and creeping stems that root at the leaf nodes.
It was originally introduced for a shade ground cover. It likes moist, shady spots such as under trees and shrubs. It's been said if you can take away it's favorite growing conditions you can discourage it from growing there. I am not so sure that works well, I have this weed growing in the driest spot under some house eves, where not much will grow, the ground is rock hard there and this creeping Charlie still manages to grow there, I keep digging it out, just to see it pop up again. You can try to hand-pull but aside you get every little piece of leaf or stem it just will grow back from the pieces left behind. If it gets into your lawn, it will completely take it over until no grass grows where it grows. I believe birds must spread the seeds also, then I start finding it in areas it did not grow before. This also is growing in parts of my rock-walls, which makes it impossible to control

Hyacinthoides hispanica also called Spanish Blue Bell

These flowers are widely grown around here and I see them sold in nurseries. I have to say they are pretty and are slightly fragrant. The original flower color of the species is blue but mostly you find a Hybrid plant in gardens which can be blue, lilac, pink or white. The species grows naturally in the Iberian countries and North Africa.
They are on the highly invasive plant list for the UK and many other European countries and also crossbreed with native related Plants there.
But they are not only invasive in the UK. I see them in many wild places around here. This plant sets a lot of seeds and they all germinate. The only way to control them is to cut of the seed heads before they drop. This wouldn't be so bad if you only had a corner of them. I on the other hand have them everywhere. My front rock-wall used to be covered in them, it was a sea of blue in Spring. One year I sat in my front rock-wall and dug out as many as I could. It made a dent in them but as they drop a lot of seeds between the rocks and boulders I don't think I'll ever get rid of them. I also have them in many places in the back, sometimes they just pop up somewhere. I now cut as many of the seed heads off as I can unfortunately there are always some I don't notice in the bushes. I also cut off many of them before they grow to big, thinking that like in Tulips they need the flowering cycle to feed the bulb. Maybe in 10 years I have starved them all. I have heard, if you grow them in a dry woodland area, they are not supposed to spread as much. I rather not have them, there are many plants which will be just as pretty and will be better behaved.

These are probably the worst plants I ever had in my yard in all my gardening years. They don't just keep me to busy weeding all the time they ravage the natural environment in many places. I still can't believe with the knowledge we have today about the invasiveness of some plants that they are still being sold in many places. I make it a point whenever I come across some invasive plants in Nurseries I let the people working there know what they are selling there.

So please do not plant these plants!


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