i live in zone4/5 Michigan USA..
sun and heat are needed here as well
I use a small
greenhouse for tomato and sometimes pepper plants in the summer and i grow greens and salad crops in it in the winter, also works well to use coldframes if you have a way to keep them watered..drip irrigation works best for that.
raised beds ..sometimes are helpful, esp if you can irrigate with drip or get
enough water.
i plant fruit
trees on slopes around the house so that frost drains away or in
hugel beds in my
perennial garden areas.
you can use reflective surfaces and walls, reflective mulches, foils, white paint..etc..or you can also use things that will soak and retain heat like dark surfaces, rocks, tiles, etc..
water can also be used to store heat like in barrels
buy the hardiest produce you can find..shop by zone.