I have found my Oenothera berlandieri 'Siskiyou' to be invasive - to a point. It seems as though it will invade bare soil areas until it meets either mulch or turf (fescue in my case); it totally stops at the turf but an occasional sprout pops up in the 3-4" thick mulch. It is almost like you can define the space you want it to grow in by mulching around a bare soil area. My O. macrocarpa (Missouri sundrop) has enlarged itself for three years now but has not escaped to other parts of the perennial garden. I can't speak to other species.
hortster

I have Siskiyou and it can be invasive but I keep it in control by deadheading to keep it from forming seeds and giving the seedlings away.

Just FYI, 'Siskiyou' is also listed as a culitvar of O. speciosa, of which there are several other varieties. In any case, they will all spread rather vigorously.

I think I am going to plant it with an edge around it so it can only go so far. I'll just have to watch for seedlings. Later, when it needs to be divided, I'll out some where it can do its thing.

I wish I could find something "invasive" for the mostly shady area I have under birch trees where nothing is happy!

Thanks for the help.

Sue - when you thin yours out later, why not try some in your shady area? I did the same thing and while not as vigrous and thick, the ones I put in a really dry shade area are surviving and blooming.

Sue36 -
I have had pretty good luck with Liriope muscari 'Majestic' under my grove of 7 river birch trees. It does OK in zone 6, gets a little "iffy" in zone 5A and further north. I wouldn't call it invasive against the birches' root competition but it holds its ground pretty well, especially if you give it a shot or two of soluble fertilizer and adequate water during the growing season. You might try a dozen and see how they do.
However, don't make the mistake that I did at first - I got Liriope spicata and it WAS VERY INVASIVE. It took me three years to stop it and get it eradicated!
hortster

Here is a link that might be useful: {{gwi:269666}}

Sue, another suggestion for your "problem area" if it can be described as "dry shade" is any of the Lamium.

Wow, thanks for the suggestions. It is definitely a problem area. When we bought this property it was where the farmer's rock pile was. DH and I removed all the rocks (did I mention snakes?) and added loads of compost. Garden did great for 2 years until the birch roots took over the compost. Nothing else has changed, but everything got sort of sickly this year. I've pulled out many plants and put them elsewhere. It will be a major project to rehab it next year.

I suggest Ajuga Reptans for the shaded area. It should be hardy in your zone, It will grow in shade.

[I think I am going to plant it with an edge around it so it can only go so far.]

Define edge. I thought a 3' concrete walk would be a good "edge". It wasn't. The runners went under the walk and kept going. I couldn't rip out the walk to get to the runners, so the plant won. I finally got rid of our evening primrose problem; we moved to another house. ;-)

You will be giving away Evening Primrose to friends, neighbors, passers-by, etc. I agree with Gyr_Falcon on your edge idea. They are pretty, but... :)

It's invasive here as well but I'd qualify that by saying if you love it, you'll be happy it spreads as quickly as it does. It's an attractive, zero-maintenance perennial that sustains pollinators so I'll admit I let it do its thing for the most part in my garden beds. Not even mulch spread over corrugated cardboard slows it down so I'm guessing unless I resort to chemicals (I wouldn't), it's here to stay since it spreads by runners.

Do I wish they didn't spread by runners? Yup. Would I wish them gone? Nope. The bees, butterflies & hummingbirds need as much sustenance as my garden can give them each season.

Oh yeah... word to the wise. I never planted ajuga in my cottage garden bed at the back of my garage but there's a HUGE patch of it growing where I never planted it. Be afraid... very afraid of it unless you really, really love it.

Is this Yellow Evening Primrose, or something else?

Here is a link that might be useful: Yellow Evening Primrose?

I love the smell of Siskiyou, but I would not have it in my garden again. I'm still pulling the stuff out from a few years ago. It's very pretty in masses.

I just love people who give a ⢠name to a wild plant. They even gave a Northwestern mountain name to a Texas southwestern plant. Way to go. I know it by O. speciosa var berlandierii. It grows wild around me and I like to place it on walls and let it roam in my grass (what wild grass that I have). I let it wander at will. Yes it gets into my garden , but , hey, I am not a neat gardener. If you are, rip it out now. It is a thug for a small garden and it will cover an area and look best when it is bloom and then , in Texas, it disappears after awhile. Google it up in DG and there are lots of comments evenly decided between positive and negative.

This plants home ground is some pretty rangy thin soil. Some semi arid wildflowers when given good fertile ground and ample moisture will quickly die from such rich environments. This guy, on the otherhand does not die. it probably thinks it has died and gone to heaven. It has entered the land of milk and honey as far as it is concerned and morphed into a thug.

Mine normally stay somewhat contained, but I starve it. It gets nothing from me. It does go for the deeper dirt. It does not like my thin rocky gravelly dirt but likes the ground that has been effected by leaf litter and the deeper clay of the adobe soils over the thin rocky Brakett soils.

In N California it is somewhat invasive but lovely, so just cut it back or pull out handfuls to control for size. This was an old thread but I’d like to add that it is very special in flower arrangements. Lasts for ages, and curls in delicate twirls around other stiffer stems or droops gracefully around the vase. Enjoy it.