peach leaf curl is one thing to watch out for

Peach leaf curl, which is a fungal infection, is spread in the rain and affects the leaves from spring onwards. It will severely weaken your tree and its fruiting if not treated.
You can overcome it in two ways. Either keep the tree in a large pot and move it under cover during the winter and spring until after flowering. Or, treat by spraying with Bordeaux mixture, a copper based fungicide, several times from before the leaves open until after the fruit set.
Bordeaux mixture used to be allowable for organic growers, and I think it is only the copper contamination which is why it is not now permitted as 'organic'.
Some people just cover their trees with a plastic 'shelter' during winter to keep the fungal spores off the branches.
The other pitfall is at flowering time. Many nectarines flower very early and if frosted you will lose all the fruit for that year. You MUST protect the flowers and embryo fruit from frost.