I live in Melbourne Australia, not sure of the zone, but I can always grow something 365 days a year. My biggest problem is sooty-mold. A fungus that has all but destroyed my tomatoes and snow peas. It affects different crops. I have found that the Italian variety "Roma" tomatoes resist best.
Our summer is finally coming to an end after the hottest March on record. (14 days over 30C) Not the highest maximum mind you, but the highest averages of minimum and maximum.
I find great success with pumpkin. They are easy to grow, nutritious, versatile, very resistant to disease and fungus, and will keep for ages in the right conditions. (Hint, check out where the term 'root cellar'
originates) We really need to also talk about methods of preserving the food we grow because the best crops will only ripen for a few weeks a year. We need to re-learn the old ways of preserving without refrigeration and artificial ripening techniques.
So, thanks to AGW, and modern horticultural hybrids, its getting easier to grow these warm season vegetables in Melbourne. There is even now a variety of banana you can grow in Melbourne.
But, back to my garden. I have about 300 sq mt in my back yard for growing and I have planted 1 orange, 1 mandarin, 2 apples (narrow 'ballerina' hybrids') and a very young macadamia. the mandarin and orange do very well, and the birds and worms certainly love my apples. I also planted 3 cantaloupe vines this year. They did very well. I harvested 11 a few weeks ago and they are very tasty. After harvesting the pumpkins, I generally pull the vines out and plant snow-peas for winter, but this year, thanks to our record hot March, I noticed that the central clump was sending out fresh vines, so I left them and watered them. Well, now I might get a second crop of pumpkins! Very, very unusual.
I also grow strawberries successfully, but the snails, birds and bugs generally get most of them. I find raspberries very easy to grow. They only fruit on last years canes, so you always have the fertile canes producing fruit and the canes for next year growing alongside. I put nets over them to keep the birds away.
I don't do this because it is cheaper, in my part of Melbourne fresh fruit and veggies are cheap and easy to get. I do it to keep the practice and knowledge. And because home grown is so much tastier.
Anyway, finally we are having some autumn weather and it seems to be cooling off, I will start planning my winter crops, mostly peas and beans.
The important thing here is to keep trying, see what suits your particular micro-climate. What grows well for your neighbour, might not grow well for you. But, if you are just starting off, I recommend pumpkins, snow-peas and beans because they are so easy and disease resistant, they will encourage you with early success.
Well - long post - I'll go now, but I love to read these stories of how you go under tough conditions. I know I have it easy in a mild climate.