[Growster...]

Thats the idea anyway, to save space and to have more plants in my section of the polytunnel, I am planning on making another six, I may make the others slightly wider so the bag flattens out a bit mainly they are for different types of toms my melons I will grow in a big box of compost.
I am also planning on fitting a drip feed system to keep them watered if I can not make it over there for any reason.

What a great idea! Like that!

Is there room for an upside down 2 litre coke type bottle with the bottom cut off and tucked in at the end for watering?

[Spana]

I wonder if the compost will get too hot with the bag on its side like that

[kevinp]

It would be easy to make them a little longer to be able to fit a waterbottle,

Spana I have no idea but I wouldn't expect soil to get any hotter if it is stood up or led down, it might even be cooler with air all around the sides rather than just flowing along the top.;

[mumofstig]

If you make the drainage holes in the bag an inch or so up from the bottom, you will keep a reservoir of water at the bottom to help stop them drying out when it is hot