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Plants that take over

I was just noting on another thread that cilantro tends to reseed itself and spread quickly, but it's easy to uproot so not a big problem. More annoying are the plants that spread via underground roots, like mint - I have to do some major root-ripping each spring to prevent my herb patch from become a mint meadow.

But the worst by far that I've encountered is horseradish. I planted some about ten years ago in a community garden. Nothing much happened, so I assumed it didn't "take" and forgot about it. The following year, suddenly there was this huge plant that looked like a small palm - sure enough, my horseradish had established itself. But at the end of the season the root was no better than those I get at the supermarket, so I pulled it out and figured I was done with it. No such luck.

The following year there were bunches of horseradish plants growing all around the area of the first. That's when I did some research and discovered that it spreads via deep underground roots, and that these roots are very fragile, and that any part of a root can establish a new plant. In the end I had to completely dig up an area of several square yards, to depth of close to 18 inches, and literally sift all the dirt to get rid of every bit of root. Shortly afterward I moved to where I am now, and have my own garden, so I hope it didn't come back to plague whoever inherited my community plot.

Anybody else got a good plant invasion story?

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  1. I have finally tamed the mint and eliminated the horseradish. If you want mint, take a 5 gallon plastic bucket and cut out the bottom. Bury it so that there is half an inch of lip above the soil line. Fill it with soil and plant your mint there. If there is soil on the lip the mint will make a run for it. Otherwise it seems to contain it. Unfortunately you will have to replace the soil every 3-4 years. We are planning on putting it on the far reaches of our property and letting the mint go wild there.

    8 Replies
    1. re: AGM_Cape_Cod

      Your mint must not be as vigorous as mine, which jumps over a board barrier a couple of inches tall and will go several feet onto a concrete patio if we let it.

      Some others that seed promiscuously: lemon balm, nepetella and garlic chives.

      1. re: Eldon Kreider

        Speaking of nepetella I found out something interesting last year when I brough my plants in, unlike most herbs nepetella provided its gets warmth and sunlight never stops flowering. I brought one in in late summer early autum while it was flowering full expect it to drop blossoms and go semi-dormant. It not only didn't drop blossoms, it kept getting new flowers all though the winter of course there were no seeds (since there were no bees inside to pollinate. but it was kinda nice to have little flowers in the middle of January.

        1. re: Eldon Kreider

          Noooo, the evil garlic chives! Have been battling them for years. I try to pick all the flowers before they can seed further, but to no great effect. Have you had any luck taming them?


          1. re: cayjohan

            We plant them next to parsley and just let 'em duke it out. ;)

          2. re: Eldon Kreider

            Maybe it is because the mint is in a shady location.

            Are garlic chives anything close to spring onions which have infested our property for years and are impossible to get rid of?

            1. re: AGM_Cape_Cod

              they are a flat leafed allium that are a good bit taller and have very pretty flowers (the fact that the blooms are attractive is one reason why they infest gardens - if you dont let them go to seed they are manageable.)

              A useful chinese ingredient.


              1. re: jen kalb

                jen, that website, dave's garden, is nice.

            2. re: Eldon Kreider

              Garlic Chives. Planted a few in the flower box along the side of the house, along with some oregano, basil, and tarragon. It was an herb garden slaughter.
              They not only took over the flower box, but they even come up through cracks in the driveway. They are so thick I'm thinking about putting them in for a lawn. It would just smell incredible when you mow.

          3. I have the same horseradish bedevilment. I just gave up trying to completely eliminate it and decided to do a periodic harvest followed by a bloody mary, peel and eat shrimp fiesta, make horse tuna dip and then a pile of horseradish sauce for family and friends (the same ones who get zucchini mysteriously dropped on their doorstep).

            I also have a lingering rhubarb taproot that seems to extend the full length of my raised bed (20 or so feet). Then there are the horsetail... OK I have to go have a good frustration releasing cry.

            1. In defense of horseradish, it naturally deters some bug pests, and some say it improves your potatoes' growth (provided you're planting taters). But yeah, we usually plant it in a bottomless container.

              Last year we put in some borage as a companion for cabbage (deters cabbage worm and attracts beneficial insects), and it got huge, toppled a bit, and almost did in the cabbage it was protecting. We did not know this going in -- and we did a bit of reading but somehow missed that part -- but I think borage is on the banned list for our garden now. Or at least it gets a pot or its own mini-bed or something.

              4 Replies
              1. re: harrie

                Good luck getting rid of the borage. I haven't planted it in 10 years, but it still pops up all over the place. I let it stay in the "blue border," but pull it up everywhere else. Those plants get painfully prickly when they're mature.

                Arugula is another plant that is here to stay, but I don't mind. I *wish* my cilantro would self-sow, but it never has.

                I've heard that Jerusalem artichokes can become a problem and have avoided planting them for that reason. Anyone have any experience?

                1. re: Glencora

                  Prickly, hmmmm....maybe I can coax it over to the groundhog side of the garden. A nearby farmer says he uses okra for that purpose, so I was going to try that; but if borage will do the trick and it comes back anyway, hopefully I can just do some transplanting.

                  1. re: harrie

                    Borage (why does my computer not recognize that word?) has a long taproot, so it might not transplant well, but it grows easily (too easily) from seed. I'd try that.

                  2. re: Glencora

                    Yes, I'll never plant jerusalem artichokes again. We dug them out finally but once you know what the plant looks like, you will probably spot it in thick patches in certain farm yards. It gets very tall and has a yellow daisy like flower.

                2. My mother would also have pumpkin problems... She would often used the Jack O' Lantern as part of the compost pile and no matter how hard she made sure to chop up the pumpkin and make sure there WERE NO seeds in it... without fail, fall would come and she's have a pumpkin vine growing somewhere in some obscure corner of the garden... LOL!!


                  5 Replies
                  1. re: Dommy

                    Our nightmare plant was Psyalis (ground cherry or Japanese lantern) . No matter what we did to remove it it would come back again and again year in an year out spreading farther and farther. I think we've finally gotten rid of it now, but even to this date I'n not entirely sure......

                    As a variant, also have the memory of the bean incident a.k.a. the "nightmare I brough on myself". as part of an agonony project I am working on, I used to (and still do on ocassion) buy fairly large quanities of an Asian legume known as the rice bean (a small usally hotdog colored bean with a large raised hilum) The work I was doing would leave me with a fair quantity of excess beans far far more than I could eat. Since The were also undonatable once I was done with then (my local foodbanks have a strict policy of not accpeting any food donations that is not in the sealed orginal manufacturers packaging) I cam up with the idea of adding the excess to my mulck pile/lawn the idea would be the beans would swell with the rains, sprout grwo a little get mown over with the lawn and or die on the mulch pile with the frost and both would get some badly needed extra nitrogen. Plus some of the beans would proably be eaten by the birds/ squirrels. A fairly good plan, and I suspect one that would have worked had I been working with any other kind of bean. The problem was, rice beans, when compared to most of the other beans commony grown for food is a lot closer to its wild ancestor in traits and aparently one of the traits that domesticity still hasn't bred out of them is a high incidence of long term seed coat dormancy and need for "nicking" (i.e. a lot of the seed have seed coats suffecienty thick that it takes more than one year of wethering for enough of it to be worn off for water to actually get into the seed and start the germination process.) Basically this meant that in any quantity of beans I happened to spread about 5-10% of the seed did not start germinaty where I put it within the year I put it there. This wouln't have been much of a problem either, if it hadnt been for the fact that it meant that when the birds and squirrels did take some of it, a lot passed through thier digestive systems intact and came out the other side later when they were somewhre else (and germinated there) so that I was getting bean plant not only in my lawn and my mulch pile, but in my patio pots, in my flower garden in my vegetable garden and in the same of all my neighbors! even when I stopped putting beans out the problem continued for years due to all the dormant seed. Lucy for me I live too far north for the plant to get a long enough summer to flower, or I'd still be in trouble!

                    1. re: jumpingmonk

                      Seed scarification can include things like scalding in boiling water. Passing through the digrestive tracts of animals, birds, and bats is another way.

                      1. re: Sam Fujisaka

                        I know that, I just wish that so many of them wouldn't SURVIVE the trip. It the reverse of the situation when I got my hands on and tried to grow a tomato called the galapagos cherry, which it turns out after millenia of evolving on the galapagos islands (its a wild cherry tomato) had deveop the interesting quirk that it would not germinate effectively unless it was eaten and pooped out by a giant tortoise (it was more than just wering down the coats, it had actually elvolved to need something in the torotosies stomach juices. without it germination is about 5% with it its around 95. Nowadays I've actually gotten into the habit of soaking things like morning glory seeds (technically the not really morning glories but since I dont know what they actually are and they are clearly in the morning glory family I might as well call them morning glories till I can find out what they are really called) the night before I'm gonna plant (as well as clipping the end with nail clippers) not so much to help them along as to make sure that what doesnt grow this year won't return next year when I may not want it.

                        1. re: jumpingmonk

                          I know you knew. I was just gassing on to other readers. Ag research is my thing and I can be a boring old fart.

                          1. re: Sam Fujisaka

                            Dont talk to me about droning on about plants you talking to the Crown prince of the Bombastic Pedantic Droners! My family is constantly mystified as to how I can find joy in opeing a bag of beans or spices, sifting throgh it seed by seed and removing the extaneos ones (i.e. the "weed seeds" then trying to classify them.

                  2. Bronze fennel seeds like mad. It is also a lovely plant, very beautiful and fragrant and I guess you can use both seeds and fronds for cooking BUT you will spend most of your time pulling up little plants, or if you turn your back ,big plants with long taproots.

                    1. #1 Ditto the mention of Jerusalem artichokes - someone planted them in our community garden about 25 years ago - years of trying have not extirpated them. do not make that mistake.
                      #2 Comfrey - If you plant this it will spread by underground runners all over the place - do not give it garden room.
                      #3 Arugula selvatica - this one is worth planting and letting it run, different names fur the wild, small, rustic arugula - it seeds all over the place, if you are luck
                      Generally I love the plants that seed back in and the natural combos they make
                      but 1 and 2 above are just too agressive

                      1. Although I actually want jerusalem artichokes, I'm going to put them in a brick walled ex-compost bin, maybe that will help.

                        The one I've had trouble getting out of hand is Mexican marigold/mint/tarragon. It spreads by seed mostly, so when it flowers now I try to cut it immediately.

                        1. The most invasive plant I have ever dealt with is Catnip. It was planted in an 4' X 8' raised bed that was available for me to garden in at a long ago apartment. It didn't matter how much I ripped, pulled or tilled that bed, the nip would still pop up everywhere!

                          I drove by a couple years after we moved from there and not only was the ENTIRE bed full of it but it was actually crawling up the sides of the brick building! In the plants defense, this was a 130 yr. old building and I have no idea how long it had had to take such a hold. Nonetheless, I will never grow it myself! (Well, maybe in a container :)

                          1. Dill. My parents inherited a corner bed full of dill from the previous owners. They sodded over that bed ten years ago, and when I'm home in the summer and mow the grass, it still smells like dill when I run the mower over it!

                            Millet became a problem underneath our bird feeder! It totally wiped out the grass and started to spread -- luckily it died out over the winter!

                            1. I, too planted horseradish to deter potato beetles about 20 years ago. I found you can't even kill it by mulching it to death. Just about everything else will either not grow or die off if you cover it with a layers of newspaper and grass clippings. Not horseradish! The mulch only seems to piss it off. The leaves form a sort of point and cut thru the mulch and continue on as before. It only takes a tiny thread left in the ground to make a new plant.

                              1. Add oregano to the list. Freakin' plants shot their roots to the next zip code. Jfood's friend 1,000 away mention his garden received someof jfood's shoots. Never again.

                                7 Replies
                                1. re: jfood

                                  I was going to suggest jfood plant garlic chives to stop the oregano. Then the old song from my childhood popped into my head. " I know an old lady who swallowed a fly........",
                                  and I started to worry about where it might end.

                                  1. re: Bobfrmia

                                    Yeah, Bob, I keep thinking along the same lines. In my case my brain is imaging a garden version of Flanders and Swan's "The Gas man cometh"

                                    1. re: jumpingmonk

                                      If only it wasn't so close to the house.

                                  2. re: jfood

                                    That's strange - my oregano usually manages to survive the winter but does not spread at all. Maybe it's getting clobbered by the mint. ;-)

                                    1. re: jfood

                                      Is your oregano the creeping kind? On a walk today I saw a stunning lime green variety, about one inch tall, being used as a ground cover. Mine's a docile shrub-like thing, about 7 inches tall, that barely produces enough for us and is not about to spread.

                                      1. re: Glencora

                                        My oregano goes absolutely crazy, but taming it is a matter of cutting armloads of it and plopping it in a vase with some other over-achievers. Smells great in the house, and keeps the raving beast at bay.


                                        1. re: cayjohan

                                          I think it depends on what kind of oregano you have. I have a Greek oregano which has a white flower. It stays compact. One year, however, I planted some oregano seed that I think was considered wild oregano or wild marjoram. It got a couple of feet tall and had pretty pink flowers which dried well. Of course, it seeded all over the place. I finally yanked it all out.

                                    2. Not edible to my knowledge, but a Wisteria will do the same underground rooting thing. I had one in my front yard for several years. I was well aware of its above ground "vining" nature so planted it far away from the house where it had nothing to grab onto. I sold the house to someone that didn't mow as often as they should have. A year or so later, I drove by and there were baby Wisteria-s all over the yard.

                                      As to the herbs - after reading this thread, thankfully, I always plant mine in pots.

                                      1. Due to some random birds my yard has become infested with brazilian pepper trees. They drop thousands of small pink berries, er, peppercorns. The USDA now classifies them as a pest species.
                                        I'd much rather have a mint problem, but it doesn't grow well in this dry climate.

                                        1. Aside from the mint problem, I also have an oregano problem (purple flowers, don't know what kind). This year's new "pest" is lavender. All of my plants are in pots and many of the pots this year have new oregano plants and lavender plants (some 8 feet away). I happen to love lavender so I am fine with it, but I never knew this could happen. The oregano, on the other hand, is just too much. I wish I was the person with the dill problem. I never seem to get enough, but I remember my uncle having tons of them when I was a child.

                                          1. I too, have a rogue horseradish plant in my daughter's garden. I know better than to try to dig it up. Has anyone tried chemical warfare? I'm wondering if a good dose of Round-Up would work. Any advice would be appreciated!

                                            1. We have a stone/pebble patio that oregano loves to death. Seedlings everywhere - I thought mint was bad. It's nothing compared to oregano. The violas are pretty, though. :)