We have been searching these out
for decades now. There are many perennial
vegetables in the tropics, but few in temperate climates.
In the past the filled the "hungry gap" in April. when last year's crops had been eaten over the winter, and the newly-planted crops were barely up.
We have listed zones for these since they overwinter.
Please look under the individual vegetables for more on how to grow them.
See also our permaculture books.
All of these are seeds except the Tree Collard Cuttings.