Gladiolas - the bulb that just keeps on giving. Even if you yank it out and toss it, dozens of tiny bulblets will have already formed and drop off. And EACH ONE makes another glad.

Ceratostigma - I don't like deciduous groundcovers, although it has lovely blue flowers and blue is a rare/prized thing in my garden. It's got a root system like vinca - virtually impossible to get rid of!

Spirea - I yanked it out. Three years later, a tiny piece of root sends up another plant. Gotta respect something that persistent through our drought-tormented summers, so this time I let it stay.

When we were first landscaping, I briefly thought about planting strelitzia, the bird of paradise plant - it is xeric and evergreen, and my mom, who was living with us at the time, adored the flowers. But a neighbor's house periodically disappears behind the massive, overwhelming clumps of four BOP shrubs planted in the front. She chops them down, and they come right back up again. I think they actually form the foundation of her house, and she'll never be rid of them.

Worst of all: oxalis pes-caprae, aka Bermuda Buttercup. Before I started gardening, I used to think the bright green cloverleaf leaves and nodding yellow spikes of flowers were so pretty. HA! Only when you garden do you discover how pernicious, indestructible, and evil this weed is. Digging out the soil and replacing it didn't work, because it happily migrated in from both my neighbors' yards. The best I can do is keep it from smothering my plants. Nothing like having to weed the same bed four times in three months to make you feel like Sisyphus rolling the boulder up the hill in Hades - and I have 15 separate garden beds.....

Jkom I hear you on the gladiolas. My mom had a similar infestation a few years back. And they were all her least favorite color--orange.

I always loved Bermuda Buttercup, and I tried to dig one out once and plant it in my yard. Thanks for posting this, jkom.
I planted four-o-clocks once, too. Still picking them out.
The most horrifying, though, even worse that horsetails, is the blue dawn flower perennial morning glory that has taken over shrubs next door. It's like kudzu.
Renee

TRUMPET VINE (Campsis radican) - once planted, shoots offspring everywhere, you will be pulling it forever.

Wild Strawberry plants - cute for a while, until they take over your flowerbeds like wild fire.

I've not had a problem with 4 Oclocks because I pick off every seed, and only grow a few plants.
Gladiolas and the more "plain" crocosmia...oh, my. I've had a time with them. I planted many kinds of glads, in all different colors and they ONLY come up in this peach color I hate. I don't know why I hate it, but I just do.

I have planted some things that are supposed to take over, but they won't. They behave themselves and stay in nice little clumps.

The things I don't want in my yard are the only things that volunteer themselves and thrive.

Virginia waterleaf, Hydrophyllum virginianum. It's a woodland wildflower that is actually endangered in some states, I understand. They can come get all mine, if they like. It reseeds everywhere, makes clumps of rhizomes that colonize an area and won't allow anything to grow thru them. Grr. Invasive native. Damn weed.

I'm zapping the first signs of Moonflowers and 4 o'clocks in certain areas around the house this year. I'll keep them in othe areas, but they are invasive where they put on a lot of leaves and no flowers because there's not enough sun.

I sure want my red 4 o'clocks to do better this year, they are just stunning!

Thanks for this topic to help all of us in choosing plants.

Buttercups are horrible! I've been trying for years to get rid of them. Am on the lookout now for the first sign of any and out it goes.

HOLLYHOCKS>>>>worse than horrible. I just wanted a something with a little height to fill a corner, so planted a couple of the new shorter varieties. What a mistake.

I have houttuynia cordata the chameleon plant. The worst thing I have ever had and can not kill it! Please don't try it!
Ellen

I now plant 4 o'clocks only where there is a lot of space -- out in the deer resistant garden. I learned my lesson when I found tubers the size of big sweet potatoes!

Off topic -- I planted seeds in February in spots where voles started digging tunnels. I don't know if they like 4 o'clocks, but they sure ate ALL of my Dutch iris bulbs and the roots off many echinacea. :-(

Flowers that won't leave unless you get rid of the seeds and dig out the tap roots (that I'm sure go to the center of the earth): bronze fennel and baptisia.

Cameron

"The things I don't want in my yard are the only things that volunteer themselves and thrive."

And grass! I once thought about writing a book titled "Only the grass grows in my flower beds". Ha! I thought I might include all of my gardening misadventures in the book but alas, I decided it would be too depressing.

MeMo

Autumn clematis...it will strangle every living thing in sight. I dig and dig and cut and pull to no avail. Never ever plant it. c

I love my Four O'Clocks. Yes, they do self seed but that's a good thing. I just pull out the ones that start to grow wherever I don't want them.

Ditto, trailrunner! I have the same problem with autumn clematis. I can't believe I actually planted one to cover an arbor, last fall.......At least that one will be where I want it! Lol!

OMGod.... Cuban oxolis has taken over with no hope of ever getting rid of them not to mention the asolutely hateful forget me nots Errghhh!!!the only good thing about forget me nots is they really bring in alot of bees.