Posted: 26/03/2015 at 00:03
To be different I have been using growbags (only 1 year of experience) - the top tip with growbags is check the volume - standard growbags are something like 25 litres but if you look around you will find 38 or 40 litre ones for almost the same price, perhaps even less if they are in different shops/garden centres! All have space for 3 tomato plants, but clearly some have nearly twice the volume for roots compared to the others - more root space is a good thing!
It probably isn't worth worrying too much about any claims for how long they will feed the plants for, as advised you don't need feed until the flower trusses (branches) appear - you will be entering a lottery over compost quality anyway whether you use growbags or buy compost for pots. Again whichever you use make sure you break up the compost before planting out into it - you will naturally do it when shovelling it into pots, growbags are best pummelled before you cut them open.
One great tip I got last year for indeterminate tomatoes is rather than using canes for support, drop a string from the roof to a peg in the pot/bag and wrap the main stem around it as it grows (assumes you aren't wanting to move them around).
Has someone explained that there are 2 types of tomato plants - intermediate (vine) tomatoes which need support and are forever trying to split (need to pinch out the side shoots as they develop, once you learn to recognize them), and determinate (bush) tomatoes, which I haven't grown but I believe they are self supporting and don't grow side shoots. Understanding which you have sown may help with planning support etc.