Root pruning roses for containers (and which compost to use)

I've bought some David Austin roses, some of which I plan to keep in planters.

I've found this article by Robert Mattock which says to root prune roses by cutting back the tap root.

It also says to use a special compost.

1) When is the best time to root prune roses? Can it be done any time for containerised roses, or should I wait until they are dormant?

2) Also, which compost should I use? Would a John Innes No 3 based compost do or something different?

Thanks in advance

Alex

 

I've planted several bare root roses in the ground in April ... it was a bit late to plant them, as bare root are normally planted in autumn

I used Plagron Batmix compost , some rootgrow and a few handfuls of vermicompost (worm humus) together with a handful of volcanic rock dust as a top dressing ...

a bit overboard for some, but IMHO, well worth the effort

this is the compost:
http://www.norfolklights.com/bat-mix-50-litre-sack-plagron-p-1654.html

it has worm humus, but I added extra
http://www.1-hydroponics.co.uk/grow-media/plagron-worm-castings.html

as for root pruning, I have never tried doing that with roses, but have a look at airpots .... I use them for loads of plants that I nurse before planting them out in gardens and they work extremely well .... they are cheap, and there are some very large ones available (a 30 litre airpot costs just over £8):
http://www.camgrow.co.uk/air-pots-30-l/

http://www.airpotgarden.com/

all the above can be bought from hydroponic stores, or on the internet ... volcanic rock dust can be bought from B&Q (£5.98 for a 10kg bag)

I have previously used John Innes #3 with roses, and added approx 20% well rotted organic farmyard manure (those that are sold at garden centres in bags) mixed with some topsoil from the planting hole ...

bear in mind though, that after 6 weeks, you will need to fertilize as the compost has only enough nutrient for 6 weeks

 

I have roughly followed Robert Mattock's methods regarding container roses for a number of years and I have not been disappointed.
I have found that a Spring application of 50ml per container of Westlands Slow Release fertilizer (now called "Nutri") keeps them going for most of the season. Spray regularly - early morning or late evening - especially in damp weather- with Roseclear.
I have several roses which had previously been growing in the ground for ten years which had to be moved and have transferred quite happily into 30 litre containers.


Another article regarding Robert Mattock's methods with container roses
http://www.telegraph.co.uk/gardening/3323505/The-root-to-pots-of-success.html

 

Thank you for your advice peeps

 

Another question - if I plant them in containers now, do I give the roots a trim or do I wait until Autumn and then do it while they are dormant?

 

Hi owl and apologies for the confusion.

They are currently in their plastic pots as I've only just bought them, so I want to plant them in containers and want to know whether to trim the roots now or else wait until Autumn, then lift them and root prune.

Thanks in advance

 

Okay thanks Owl for your help

I'll put them in containers as they are and when I come to pot them on in a couple of years, will have another think about it then.