Weeding on an old greenhouse plot

Hi all

Last summer I bought a house with a large garden, which at the back had 2 greenhouses on one side, and a load of wild mint at the other. We knocked the greenhouses down and removed all the vegetation that was there. Over the winter a huge amount of what looked like wild turnips grew to about 5 feet. They swamped everything else so that nothing else grew. I've dug them up and want to grow vegetables there (if not this year then next). My question is how do I prevent these things growing again? As the greenhouses were there there could be all sorts of things in the soil and anything could grow and ruin my efforts.

Thanks for any help

 

Weedkiller? e.g. something Glyphosate based - "Roundup". If that doesn't kill it then "SBK".

Cover with tarpaulin / plastic sheet for the Summer and rob it of light.

"Never let it see a Sunday" - hoe the tops off, at least once a week, to weaken it