Getting rid of crocosmia

[Purple Primrose]

About a year back, I dug up loads of Crocosmia that had been spreading and put it in a heap to rot down. All the corms on the surface of the heap sprouted so I pulled them up in the hope they'd die. More corms sprouted leaves. Any time I tried to turn the heap (about a cubic metre of corms/leaves etc) any corms that saw daylight started to sprout. It won't compost and I don't want to use weedkiller. How do I kill it all off?

[ameno]

Drown it. It's what I do will all my perennial weeds (bindweed, horsetail, couch grass and dandelions mainly. But I also occasionally have to drown comfrey roots, spanish bluebell bulbs, wild garlic bulbs, and crocosmia corms).
Collect up all of the corms, put them in a barrel, cover with water and weigh down with a couple bricks so that they don't float to the surface, and leave for a while until they die. Be sure to put a lid on the barrel, as it will smell.
How long they take to die will depend on the time of year. They'll die quicker if they are in an active growth period, whereas if they are dormant it will take longer. If you do it now, they should be dead by mid-summer I should think. You can test them by seeing how soft they are; dead ones should start rotting in the barrel and be going soft.
Once they're all dead, you can just put them on the compost.

[Nicos]

Simply give it away! Can’t understand why you would want to kill them.
If regularly thinned they would finally disappear, or at least become less irritating to you!
Leave some outside your house with a sign…take some to a charity shop….Guerilla planting maybe in an urban area? Freecycle?Preloved….or simply take them to market stall selling plants for them to pot on and sell.

Personally I would absolutely love to have as many as you could offer me! I can’t be the only one
You would put a massive smile on at least one person’s face.

[ameno]

Simply give it away! Can’t understand why you would want to kill them.
If regularly thinned they would finally disappear, or at least become less irritating to you!
Leave some outside your house with a sign…take some to a charity shop….Guerilla planting maybe in an urban area? Freecycle?Preloved….or simply take them to market stall selling plants for them to pot on and sell.

Personally I would absolutely love to have as many as you could offer me! I can’t be the only one
You would put a massive smile on at least one person’s face.

They're a terrible weed here in the South West, especially so in Cornwall. In fact I think they're even listed as an invasive non-native plant by the government (which means guerrilla planting would probably be illegal) . They colonise verges, hedgerows and clifftops in no time at all.

They might be less of a problem grown somewhere with colder winters, which might keep them in check a little more.

[Gearoid]

I put mine (the weedy "montbretia") in the green recycling bin for the council.

[quanglewangle]

However you get rid of it, don't spread it. It's an invasive weed and spreading it is an offence.

Montbretia is listed under Schedule 9 to the Wildlife and Countryside Act 1981 with respect to England and Wales. As such, it is an offence to plant or otherwise allow this species to grow in the wild.

[DEFRA Non-native Species Secretariat http://www.nonnativespecies.org/down...nt.cfm?id=362]

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edit: defra site doesn't make it easy to get to the link so I've put it here: http://quanglewangle.com/uploads/ID_...tia)%20(2).pdf
Paste it into your browser.

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Here is Cornwall is spreads quickly over any uncultivated ground in large areas, destroying habitat and reducing bio-diversity.

When we moved into our present house ten or so years back we got a contractor with a tractor to clear the garden, which had been a market garden but hadn't been touched for 20 years, and that yielded just short of two builders' bags of rhizomes.

[ameno]

When we moved into our present house ten or so years back we got a contractor with a tractor to clear the garden, which had been a market garden but hadn't been touched for 20 years, and that yielded just short of two builders' bags of rhizomes.

I'm not surprised. I'm clearing a pretty small patch at the moment, a strip maybe 1.2m by 40cm. I've cleared about a third of it so far, and already had a bucket full to overflowing of corms, just from that little 40cmx40cm area.
Mercifully, 99% of the corms seem to be in the top 3-4 inches of soil, so I don't have to worry too much about missing ones deeper down and I don't have top sift through large volumes of soil.

[quanglewangle]

... Guerilla planting... .

For the avoidance doubt, this would be an offence (in England and Wales} under Wildlife and Countryside Act 1981.

[Purple Primrose]

Crocosmia is quite a problem in gardens here (small island in Orkney) so nobody is going to want to take it off my hands and I certainly wouldn't consider spreading it onto the fields or natural heathlands. I literally have about a cubic metre of corms. Drowning it sounds like a great idea, Ameno.

It's a shame Brexit means I can't post any corms to you in France, Nicos.

[Mark Rand]

I had some crocosmia in my front garden. Quite pretty. It all died out. I wish horsetails were pretty or tasty though.

[Plot70]

I put most things I want to get rid of in the chicken run. They kick them around until they are dead and add a bit of manure for a good start in a compost heap.
My bulk method is to put all the weed roots including couch grass and dock in a large clay block built raised bed and cover it with horse manure and add the shed latrine tank. It pickles the roots and in a thin layer of topsoil over the layer cake I plant squashes. They grow well and very few weed roots come through. A year later a get a huge quantity of stuff that looks like expensive bought in compost containing all the nutrients the weeds pinched when they were growing.

[Babru]

I wouldn't plant crocosmia in my garden, as I know what a pest it is - and if you leave one tiny com it multiplies very fast. I do think it looks lovely though, so I took some Lucifer a friend offered, and kept it in a big tub. Blow me, a few years later, there's Lucifer coming up in a flower bed, clearly seeded itself. So, doesn't just spread by corms.

My new garden - no crocosmia or any of the other things I found to be a menace - alchemilla mollis, orange alstromeria, inula hookeri, red valerian, lysimachia Firecracker, scilla, Spanish bluebells.....

[Nicos]

For the avoidance doubt, this would be an offence (in England and Wales} under Wildlife and Countryside Act 1981.

yup - that’s why I suggested urban…but spot on Q

[Nicos]

Darn Brexit indeed PP….I could have swapped you some corms in exchange for some humanly transported voles!
Those are probably the reason I can’t grow crocosmia

I’d absolutely no idea they were so invasive

[Martin H]

I have three types of Crocosmia in my garden: Lucifer, a common or garden reddish orange one, and a light orange.
Maybe I should plant them among the Spanish bluebells and let them fight it out!

But I do like them, just have to keep a close eye on them. They are no more invasive than raspberries, after all.