Some plants are just naturally ready for changing climate, and many of these can be grown in colder areas if they are kept in pots and brought indoors or into a greenhouse for the winter. Some have the added advantage that they find few pests in our area.
A friend and I share plants that we put in a sunny area for the summer. We keep them in a greenhouse in cooler weather of fall or spring and bring them inside during the winter.
Our calamondin is especially delightful. Only four feet tall, it bore over a hundred fruit last year, each a little smaller than a ping-pong ball. Calamondin fruit are very tart. Some people eat them like kumquats, and they make amazing marmalade. Other citrus we have had success with include Meyer lemon and lime. We are sprouting finger limes this year from seed.
A fig tree can be quite productive, if you keep it in a sunny place during frost-free months. Figs are also very pleasant companions in a living room window. We are also just now sprouting olives to grow in pots. We will let you know how that works.
Many of these can be bought as plants at local nurseries.