I have a nameless blue aster that is very reliable here in the south. It's one of the few spreaders that I like well enough to ride herd on. Another is Black and Blue salvia.

I'd say one of my favorites is lily of the valley.

I tried for about 7 or 8 years to get this established in my gardens and had very little luck - I'd get about ten blooms here and there, spread out and lonely-looking.

Well, last year, I had a nice-sized little clump of bloom, and this year I see it has spread.

Now I'm starting to get afraid and remember what everyone has said about this plant! I may have to start an annual fall rip-out as part of my fall routine. But I will never get rid of it completely. It's just too beautiful and fragrant!

:)
Dee
P.S. I like monarda too. So far I haven't found it overly agressive. Like I said, so far...

Salvia guarantica. I control it by pulling up tubers every Fall. There's always more left behind to continue the legacy. If they introduced a similar Salvia that didn't want to travel past its bounds, I would seriously consider replacing it.

Physostegia virginiana stays around because it can easily be controlled by Fall thinning.

Lamiastrum galeobdolon is a noted thug, but it's thriving in a large, part shady bed where other groundcovers proved to be anemic.

Up until this season, I have granted leniency to Chasmanthium latifolia (river oats), but after an entire Spring pulling out baby Chasmanthium, it is now on probation and will probably go.

Other plants that I have banished over the years because of their aggressive nature:

- Helianthus augustifolius
- Helianthus maximillian
- Helianthus mollis
- Monarda 'Blue Stocking'
- Aster tartaricus
- Oenethera berlandier 'Siskiyou'
- Salvia guarantica 'Argentine Skies'

I also like Chameleon Plant but many hate it. It's invasive, but I like the way it looks in some areas of my flower bed. It's so colorful. If I don't want some in an area I can simply rip it up. It can be contained by planting in a container.

My favorite of all aggressive plants is Pink Primrose (Oenothera speciosa). These are just beautiful. They spread a lot, but it's very easy for me to control.

Well, truthfully I'm not much of a fan of groundcovers but I'll concede that sometimes a groundcover is necessary.

With that, my favorite is "Biokovo" geranium.

What plants do I keep dispite the fact that they are rampant? Lysimachia ciliata 'Firecracker' because of its wonderful foliage and Epilobium angustifolium (Fireweed, Willowherb)for the height it adds.

I find "Obedient" Plant to be extremely invasive here. I got rid of mine because it started taking over near by plants. Now I just have it in my "Rampant Bed" out in the alley garden with other agressive things that I can't bear to toss out.
CMK

Black and blue salvia--never could have too many.

I have a love hate relationship with Gooseneck loosestrief - love the flower head because it is so different from any other flower but it has been banned from the main gardens - it is on edge of the woods to do its thing - same with obediant plant. Pink Mexican sundrops I do leave in the gardens - I just love the flower poking out here and there and it is pretty easy for me to control. Johnny jump-up - they are everywhere in my gardens and yard but how can you NOT smile when you see that cute little face :) ......

Lynne

I still like Gooseneck Loosestrife (Lysimachia clethroides) -- for me in a large garden it had a dramatic effect, and was relatively easy to manage on an annual basis (simply pulling up the runners).

Ceratostigma plumbaginoides spreads quite a bit as well, but is a great late summer plant.

Japanese Anemones spread like crazy but are invaluable.

For dry shade, Lamiums and Geranium macrorrhizum spread nicely.

I'm even still a big fan of all the traditional groundcovers as well, e.g. Pachysandra, Vinca minor, English Ivy, etc. While some consider these to be too aggressive, in the right spot, in a certain type (i.e. large) garden, they are useful plants.

Cheers.

Canadian Anenome - Anenome Canadensis. Drifts & Drifts of snow white flowers in May.
Cup Plant - This is one crazy plant but it is cool!
Brown Eyed Susan - Rudbeckbia triloba. Black eyed Susan on steroids and it seeds everywhere but what a show!

Any of the Native Asters - New England, New York, Smooth Blue, Short's Aster, Wood Aster, Frost Aster. But they make such a wonderful late summer/autumn show it's worth pulling up the extras & runners.

Trollius - This was mentioned in another thread but if you can figure out how to control it's a beautiful plant in the spring with bright yellow double pompom flowers.

Also agree with above poster about Japanese Anenome - a spreader but a wonderful show.

What I find interesting about this thread is depending on everyone's zone, one person's thug, is another person's easy to grow perennial.

Two perennials mentioned here as overly agressive, Monarda Blue Stocking and Black and Blue Salvia, are welcome plants in my garden. I've had the same size clump of Blue Stocking for the third summer here. Black and Blue Salvia didn't over-winter here, and I'd grow it as an annual anytime.

I put in, on purpose, Bouncing Bet-Saponaria, because I like it so much. It's fragrant and I love the light pink flowers. I've just been pulling out pieces that are moving from the main clump to keep it from spreading. I just won't let it get ahead of me. My Purple Dome Aster, a gift from a neighbor, and lavender Creeping Phlox need to be down-sized this year too.

In the past, I have completely removed Clara Curtis Daisies, Physostegia-Obedient Plant, Rudbeckia Goldsturm, and Puple Cone Flowers because I couldn't keep them contained in one area. They literally went everywhere, even coming up between iris rhizomes!

Linda

The key to controlling some of the plants mentioned is not letting them go to seed!! Cut your Echinacea (coneflowers) when they fade before seed set, and no babies everywhere!! (They don't spread by runners, you know.) I love my one plant of Chasmanthium (Northern Sea Oats), but I cut the stems every fall and use them in dried arrangement--very lovely--and they don't seed all over the place.

I'd never call Geranium maccrorhizum or 'Biokovo' aggressive spreaders--they spread slowly and are very easily controlled.

My love-hate relationship with a thug is macleaya cordata/plume poppy (I think it has a new namme now). The leaves are gorgeous, the plants are impressively monstrous. But it runs and runs, especially in my loose, sandy soil.

My love-hate relationship are black-eyed susans. They come up everywhere but are so hardy and beautiful in the hot summer. Plus, the gold finches love their seed heads in the fall.

Forget me nots, Japanese anemones.

Sweet woodruff and all kinds of lamium.

Kate