I'm not in West Nyack (I'm further north) but am sure it is zone 6. We haven't had any frost up here yet and zone 6 probably gets theirs in mid or late October. As for local nurseries, you aren't going to be too far from Matterhorn (great plants but pricy). For nurseries I'm more familiar with Newburgh, Poughkeepsie and Rhinebeck area. Try your Rockland County cooperative extension for soil tests and info on local nurseries.

I am sorry I didn't respond before but I just noticed this post. I live near West Nyack. Rockland County is Zone 6. Matterhorn is an excellent nursery. But yes, it is pricey. There is also Van Houtens in New City and Suburban in New City as well.They are within 1-3 miles of West Nyack depending on where you are. There are several other smaller ones in Rockland and others very close in New Jersey such as D'Ercole and Di Piero's. The Rockland County Cooperative Extension offers a lot of good information. As far as the last frost free date it's May 15th. But it's unusual to have a frost in May. Good luck with your new garden.

I just joined GardenWeb and so only read this post tonight. Still can't help but laugh when people refer to Rockland County as "upstate!" There's a lot of state above us - it goes all the way to Canada!

Rubrifolia, I hope your garden is coming along nicely. It's been kind of a strange Spring and Summer, hasn't it? Welcome (belatedly) to "upstate" New York!

I live here in West Nyack. I have a different perspective. I am orginally from Vt so I think of this as down state.
Anyway, we are having a crazy non winter here. You have already started your garden. mY tulips are starting to come up and my roses are started to grow already. Good luck and welcome to West Nyack. It is wonderful here.