Does anyone know the cheapest place I can get this and root hormone from?
Don't know about rooting powder sorry.
This year I went for Chempak tomato food from Wyevale but if you wanted it delivered you could wait until Thompson & Morgan's next free P&P day and order it from their website. It's about £5 for 1kg and is a Which best buy.
But I did contemplate this from ebay
http://www.ebay.co.uk/itm/380254381344?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649
Been using that all summer at home, used wilkos liquid at the lottie as a bit of a test & it comes out well. Does the job & works out fairly cheap. I have used their liquid seaweed & elixar blue chemical feeds & they were good as well. And before anyone asks i have no connection with them.
No problem with mail order but you can get just as good and save a lot from wilk,son, I buy mine from home bargins £1-99 its one of the best on the market. I tend to buy in the winter when everything is on offer and put it away. As for hormon powder a garden centre about £5-00 ;) save a few bob ;D