Solved Crocosmia ID

@simone_in_wiltshire - if you're worried about your crocosmia spreading too much, you can plant it in a bottomless pot - as long as it's about 8 inches deep, it'll keep it from going sideways too much!
I've done that with various plants that could be troublesome - flag Iris and my Spartina grass are two that spring to mind. I use old florist's pots or buckets, and just cut the bottom out of them.

 

In our Welsh garden we were given some Lily of the Valley which I really wanted.
We planted it is a huge empty spot in damp soil and semi shade.
Perfect growing conditions for L of the V...it thrived there.
In with the L OF the V, unknown to us was was some Crocosmia...(Montbretia)
OMG how it spread..every year I pulled up the new tiny leaves.
Every year the patch just got bigger!
It can be a thug.

I have planted in both our gardens ...Wales and Scotland, the much taller Crocosmia masoniorum Rowallane yellow
It is glorious and quite well behaved.
Crocosmia masoniorum 'Rowallane Yellow' | giant montbretia 'Rowallane Yellow' Herbaceous Perennial/RHS

 

I have potted them into a bigger pot. A fox or cat has already discovered them

 

Our conditions here are normally dry on sandy soils and the thug type crocosmia is still quite rampant, whereas the cultivars are pretty well behaved. I think the further West you go (I'm in norfolk), the more the conditions seem to suit. The lake district for example is covered in escapes of what my folkes also still call monbretia.

 

C. "George Davison" is the only one other than the common montbretia (which was here when we moved in) that's really clumped up and spread for me in the dry sandy soil. Both are relatively easy to pull out when they spread beyond where I want them, but I hate to think what they'd be like in wetter conditions.

 

I dont think its the worst invasive around, main issue is it spreads via both seeds and rhizomes. In terms of damage its still much less than most bamboos, nothing like j knotweed, rhodedendron, etc.

i must admit those yellow flowers are lovely!

 

Re Montbretia, it does largely depend on climate/conditions as to just how rampant it is, but it doesn't mind drier soil either. It spreads very rapidly here in lots of sites, because it's still wetter than many areas, even with the recent climate changes. I still get pieces appearing at the foot of my back fence [we've been here over 12 years] in a raised area edged in rock, bordering the gravelled drive, where there's literally nothing for it to grow in, and the rain doesn't easily get in either due to trees and other planting. It can creep through to the bed on the inside, but I pull it out as soon as I see it. It's in lots of gardens though.

I'd class that Carex pendula as really invasive - that's another one that's rampant here. I think it is classed as invasive in Ireland. I don't know why it's still for sale in GCs etc. They could just visit this area and help themselves for free if they wanted it!

 

Down here in Cornwall, montbretia is a pernicious weed. It spreads quickly on roadside banks and in gardens given the chance. It seems to thrive in dry undisturbed ground, I pull up buckets full each year but so far have not got rid of it completely. Lucifer also spreads quite happily but not as bad as the common orange one. Montbreti produces tiny bulbils which look like pills of soil, impossible to collect and destroy, the same as celandine.

 

If only they had some commercial use, we’d be thinking they were the bees’ knees.

 

I must admit I've always quite like it. I went out yesterday to see the patches in my brothers garden (it was there when he moved in) and it's completely brown and crispy. They are in decent soil and partial shade but this summer and drought has just frazzled it. It doesn't ever spread beyond sideways and I've no doubt it will spring back next year but not a great year for it.