buying non-developable adjacent land

My neighbor's house is up for sale. I am interested in buying a small portion of his land (he has 1.8 acres in a 1-acre zoning, I have 0.8 acres). This extra land - my intention is only to use it as a garden - would substantially improve my property, giving me more waterview. Is it complicated or at all possible to purchase this land and adjoin it to my own? Could it be purchased seperately, not joining it to mine, as undevelopable land, given that it is smaller than the zoning requirements? A previous owner had attempted to subdivide the property for development, but was denied because of special waterfront set-back requirements for building.

[HomeGuru]

First you need to check on the zoning and subdivision requirements, then make an offer. If the Seller accepts, a survey must be completed on both properties, then a map drawn of the land area purchased. The County may require subdivision application and approval.
Rather than just keep the property as its own lot, you should consolidate the piece to your existing parcel.
You should hire an attorney that specializes in land use matters such as these.
It tends to get complicated if the government is involved.