Container growing

Hi I have made some big wooden boxes to grow tomatoes in for mty green house , they are about 7' 6"" long by 18 " wide by 18 " high , my question is what do I fill them with , is it best a mix of top soil and potting compost
B

 

Tomatos can tolerate a range of soils, but the key is organic matter, so heavy on the compost I'd say. Go deep with it, because toms have deep roots and are hungry! Also a basic fertiliser might be an idea. They need high phosphorus and low nitrogen levels

Something I didn't realised and had to be told was that tomatoes love heat. So cover your planting area with black or red plastic a couple of weeks before you intend to plant. Those extra degrees of warmth will translate into happier tomatoes.