Gunnera in 200 ltr pot

Morning everyone looking for some advice on what to add too the peat based compost I intend to use to grow my two Gunneras in 200 ltr pots. Now I know growing these in a pot is far from the best idea but I have no choice at the moment and I’m the type of gardener that likes to try the impossible. Next up I’m going to upset most and tell you that I’ve never used anything but b and q verve peat based to grow everything this includes things that should have never survived in this country let alone in a pot and have bags of the stuff. I have plenty of clay soil round my property that I could mix 50/50 with the compost I use to try and create a mix that will hold water well,so I would love to here everyone’s thoughts on this mix or other suggestions on different mix and amount of drainage holes I should drill in the pots and anything else the well informed members here would like to share.

 

I had a large one an offcut from the main plant in a big growers pot and it was fine. Think this winter just killed it,my fault.
I would sit it on a saucer so when uts watered some water can soak back in rather than all run away.

 

Go for it Matt

Firstly, I dont grow gunneras but if I did I would:

Mix 50/50 clay soil and mpc. I would also add a few handsful of dried manure, chicken pellets plus fish blood and bone fertiliser. The mpc wont add much except to aerate and balance your soil. (I have used my own loam as part mix for certain plants and although preferring john innes, it has worked well)
Plenty of drainage holes.....water loving but in a container these are necessary. A layer of gravel over them
Plenty of watering.
Well Matt, pretty much how you have described in fact
200 litre pots? Like the concept of that. I think it could work out well

 

I'd be a bit wary about adding too much organic matter, in boggy conditions it rots down very quickly and gives off pongy gasses.

Think I'd go for a heavy clayey topsoil along with @WeeTam suggestion of some kind of saucer under the pot so that the soil is always saturated during the summer months.
A means of taking the saucer/ gravel tray away in winter would be good.

 

I worked for a very ‘reputable’ and dare I say classy nursery in the south coast for a year or so and we used sinclaires compost for absolutely everything, Gunneras too. The sad part was the fact the compost had soo much fertiliser in (which could cause detrimental damage to ponds should they be planted immediately) however, all in pots and could sit there for ages. All irrigated with 1 litre a day on average and were anywhere from 50l plus pots up to 220l. I’d say go for it!!

 

Just uncovered a couple of my offcuts i had in small containers and they are fine,not dead as i first thought despite that winter.

Mpc,kept moist,over wintered under a slab of roof insulation.