Dig them up in the autumn or spring, split the clumps and also, if you can, remove the top corm from the pile that will have built up, to replant. Discard the lower older ones - but don't compost them!

It isn't an easy task, as the corms grow close together in the clumps.

Thank you for your reply. I'll have to do it a bit at a time as there are so many of them in different parts of the garden

I find just trying to eradicate them gives them a new lease of life. There will be so many bits of root, seeds ready to germinate and smaller corms springing into action that you'll find you have more montbretia than you know what to do with.

I find careful incineration is the best way of getting rid of the bits you don't want. The corms seem designed to roll off bonfires so burn them up carefully & rake sides to middle to make sure you've got them all.

Thank you Beattie. I usually put any garden rubbish in the garden reycling bin. The local Council turns it into compost to sell back to us (!). I see I should not do this with montbretia.

I don't know what your local council thinks about montbretia. Here it's a well known very tenacious weed. If you put it out with the garden recycling your council will be selling compost with montbretia in it for everyone to have some!

I didn;t know it was a weed, I thought it was a flower.

The weed / flower thing has very elastic boundaries. It's a weed if it's in the wrong place. Here the roadside grass verges and cliff tops are full of it - escaped from gardens & now impossible to eradicate. It chokes out lots of more interesting wild flowers. Weed or flower - you decide!

I've looked it up in my gardening book and it says flower arrangers like montbretia. I know one so she can come in and help herself. lol.

Crocosmia has the reputation of being better behaved than montbretia, less invasive anyway with bigger flowers, but I can't bring myself to even try to grow it. I see those spiky leaves and feel compelled to pull them up. Bad news for things like sysyrinchium too.....

Oh dear, Beattie! Just think what you're missing...Crocosmia 'Emily McKenzie' and her friend 'George Davison' aren't in the same league - and as for Sysyrinchium striatum...I couldn't do without them. in my garden...

I've had several sorts of Sysyrinchium and have accidentally lost every one of them. I'm the same with ornamental grasses. I only remember that I shouldn't have pulled 'that one' out when it's too late.

Oh no - accident prone, then?

Forgetful, I'd say, and programmed - I see a spiky leaf like a montbretia or a 2" high sycamore seedling and it's out before I know what's happening. I've been known to weed the lane going to the shops.....

According to my gardening book montbretia is the name of crocosmia.I didn't know they were different.

They all used to be called 'Montbretia', Casso - then someone decided to change their name to 'Crocosmia', but the 'wild' or native ones, which are probably garden escapes, do tend to be known as 'Montbretia' still.

There are lots of different cultivars of Crocosmia now, like 'Lucifer' and 'Emily McKenzie' which are much nicer and less invasive.

Thabk you for the replies. I see I have got some in bloom now. I think they are rather pretty.

Yes, they are - and I'm pleased to hear that you have some flowers. :-)