Here are my favourite books for year round growing, including UK and US ones where they generally have more challenging seasons. Joy Larkcom is particularly useful at filling the ‘hungry gap’ when winter stores and produce are ending and before summer crops have come to harvest (round about now in Wellington). Certainly a tunnel house or green house will help with year-round cropping, as will storing things such as onions, pumpkins and potatoes.
I also like the permaculture books from Kay Baxter which I think are out of print but you may find on Trade Me or Touchwood Books. Kath Irvine has written an excellent slim, spiral bound booklet about what to do and when in Kapiti and Horowhenua – usually available from Commonsense Organics.
Lots of rhubarb at the moment so made a couple of rhubarb and almond pies.