Feeding pot grown rhododendrons

[grenadier]

Please can anyone advise me on whether or not it is okay to continue giving a liquid feed to 3 rhododendrons that I have growing in pots whilst they are coming into flower. I ask because I was once told to stop feeding clematis once it starts to flower as it shorten the bloom time. I wondered if this was so with rhododendrons. 

[Graeme]

enmag
seaweed extract
and ericaceous feed -
if you have only got three try
http://www.homebase.co.uk/en/homebaseuk/homebase-ericaceous-plant-feed---1l-321150
or if you have a wilco nearby
http://www.wilko.com/plant-food+fertilisers/wilko-ericaceous-feed-1l/invt/0342205

I keep satsuki azaleas so I don't feed them before they flower - but afterwards they get everything

I also use this on all the azaleas - particularly cuttings
http://www.ebay.co.uk/itm/like/322093303691?lpid=122&chn=ps&googleloc=9046374&poi=&campaignid=207297426&device=c&adgroupid=13585920426&rlsatarget=pla-156022126866&adtype=pla&crdt=0

[David Nicholson]

I notice that of the two 'Tin Shed' bought products the Homebase product is the one on which the NPK figures are shown as printed on the label. I suppose the Wilco choice may be the same but I remember opting not to buy tomato fertiliser from them simply because no NPK figures were printed on the label.