Hardy Tropicals UK

I'm justing wondering how hard is it to control the spread of Gunnera? Does the rhizome just creep along the soil surface indefinitely and sucker everywhere?

If 1 small gunnera was planted out (5litre pot) How long would it take for that Gunnera to fill the supposed 6ft/6ft size room requirement?

There just seems to be a lack of information out there on exactly how these things spread and how fast they get to full size.

I'm still unsure wether or not they sucker like tetrapanx or if they rely on the one big rhizome and their seeds.

My experience is its one big rhizome but they are very easy to divide just split cleanly with a sharp spade once they reach a decent size.

I'd say it is one rhizome but they do spread from the centre - although they seem to stay attached to the main plant. Mine filled 6ft/6ft in about 3 years, but it depends how wet they are - they do best grown as marginals.

Saying that, mine isn't grown as a marginal and it's huge! It's been slow to get going this year due to the weird spring, but last year it was big enough to sit under to shelter from the rain by mid June.

They are very easy to keep in check though so it's not 'gunnera' take over your garden

I have the overflow from my water butt directed onto it so it gets plenty of water - but I imagine with the hosepipe ban this year the butt will never overflow so it will be interesting to see how big it gets.

Steve

Stevo wrote:I'd say it is one rhizome but they do spread from the centre - although they seem to stay attached to the main plant. Mine filled 6ft/6ft in about 3 years, but it depends how wet they are - they do best grown as marginals.

Saying that, mine isn't grown as a marginal and it's huge! It's been slow to get going this year due to the weird spring, but last year it was big enough to sit under to shelter from the rain by mid June.

They are very easy to keep in check though so it's not 'gunnera' take over your garden

I have the overflow from my water butt directed onto it so it gets plenty of water - but I imagine with the hosepipe ban this year the butt will never overflow so it will be interesting to see how big it gets.

Steve

Thats good to hear, I have wanted one but have been reading elsewhere that "It's impossible to control the spread and it always takes over" lol. I guess I could go for it now.

I'm guessing the bigger the rhizome the bigger the leaves, so cutting it over and over would mean for smaller leaves though.

Yeah that would be true. But in 5 years I've never had to cut my rhizome back. I cut some leaves back when they crowd neighbouring plants but that's it.

Don't think as it as sending out runners or pups as it doesn't. The many growing points just start to grow in different directions as they grow to the light, therefore they spread out a bit. The plant itself is still really just one large clump.

If you have an area to fill that is 6ft x 6ft I can't imagine you would ever need to cut back the rhizome, just the occasional leaf.

I'll post a pic of mine later if you like?

Steve

Stevo wrote:Yeah that would be true. But in 5 years I've never had to cut my rhizome back. I cut some leaves back when they crowd neighbouring plants but that's it.

Don't think as it as sending out runners or pups as it doesn't. The many growing points just start to grow in different directions as they grow to the light, therefore they spread out a bit. The plant itself is still really just one large clump.

If you have an area to fill that is 6ft x 6ft I can't imagine you would ever need to cut back the rhizome, just the occasional leaf.

I'll post a pic of mine later if you like?

Steve

yea that would be good.

I couldn't get a good shot of the rhizome without standing on plants but you can see that the spread in 5 years isn't much. Possibly a foot at most.

Here is the biggest leaf at the moment - this will end up nigh on 2 meters across.

Reading the sizes some websites give i would have expected a larger spread at 5 years. :'(

greendragon wrote:Reading the sizes some websites give i would have expected a larger spread at 5 years. :'(

The rhizome spread isn't much, but my 5 year old was 4 meters wide at the end of last summer.

4 metres = 12ft so you must have cut it back hard :O

greendragon wrote:4 metres = 12ft so you must have cut it back hard :O

Ok - poor maths there on my part. It was about 9-10 feet which is 3 meters approx. Never did get the hang of the metric system!

Last year I pretty much let it do its thing to see how big it could get so didn't cut it back at all really. It was HUGE!

This year I have changed a lot of my boders and wanted to put a lot more plants in that bed so I will be keeping it in check. I will let it keep 3-4 of its biggest leaves and chop the rest. Doing that will make the remaining leaves really big by the end of the season.

Steve

greendragon wrote:

Stevo wrote:I'd say it is one rhizome but they do spread from the centre - although they seem to stay attached to the main plant. Mine filled 6ft/6ft in about 3 years, but it depends how wet they are - they do best grown as marginals.

Saying that, mine isn't grown as a marginal and it's huge! It's been slow to get going this year due to the weird spring, but last year it was big enough to sit under to shelter from the rain by mid June.

They are very easy to keep in check though so it's not 'gunnera' take over your garden

I have the overflow from my water butt directed onto it so it gets plenty of water - but I imagine with the hosepipe ban this year the butt will never overflow so it will be interesting to see how big it gets.

Steve

Thats good to hear, I have wanted one but have been reading elsewhere that "It's impossible to control the spread and it always takes over" lol. I guess I could go for it now.

I'm guessing the bigger the rhizome the bigger the leaves, so cutting it over and over would mean for smaller leaves though.

ya its true they spread!!there extremely invasive here in west of ireland.They are a hated pest-spread by seed.