Nectarines are a mutation of peaches (peaches without fuzz) and grow anywhere peaches can be grown. They can grow in USDA growth zones 5-8, but do especially well in zones 6 & 7.
Yes, because we usually (in California) get lots of sun. You can grow fruit mostly anywhere.
where were nectarines originated
yes UK grow apples.
No, nectarines are peaches that have a recessive inactive version of the gene that produces peachfuzz.
yes
Yes nectarines can be canned. You may leave them whole or sliced. Boil in a syrup or water bath and can them.
No, nectarines are not citrus. Perhaps you are confusing nectarine with tangerine? Citrus fruit include tangerine, citrange, tangelo, orange, pomelo, grapefruit, lemon, lime, citron, and kumquat. Nectarines are just peaches that don't have fuzzy skins. They can even grow on the same tree as regular peaches.
No, it is illegal in the UK.
Nectarines are not a product of cross pollination. They are peaches that do not have fuzz. Some peach seeds produce trees that bear fruit that is not fuzzy. Sometimes a peach tree will bear both nectarines and peaches. Growers commonly graft branches from nectarine trees onto peach trees in order to produce nectarines.
Yes
anyone can.