Being in S.Jersey, I like Winterthur and Longwood Gardens. The Duke Gardens are supposed to be nice, but I know almost nothing about them. I did once visit the small iris garden in Montclair at its best. Rarefind Nursery, in Jackson, maintains a demonstration woodland of many Rhododendrons that is quite spectacular in season.

I live in southern New Jersey as well and my two regional favorites are Chanticleer and Longwood. Bowman's Hill Wildflower Preserve is worth a visit especially in April and May when the spring ephemerals including bluebells are in bloom.

Add the Morris Arboretum in Philly and Deep Cut Gardens in Middletown, NJ.

Chanticleer is one of my favorites.

Simple and beautiful, Leamings Run is our favorite.
http://www.leamingsrungardens.com
Not an all-day affair, cool under the trees in the summer and all done with annuals.

The Indoor Display Gardens created by Doris Duke at Duke Farms in central New Jersey have been a favorite destination for many of us for years. Miss Duke created the Duke Gardens Foundation Inc. and opened the gardens to the public in 1964. Since her death they have been administered by the Trustees of the Foundation. On May 25, 2008, at the discretion of the trustees, these gardens will be closed and their plant collections disbanded. An ongoing slide show of what will be lost can be found at the website shown below.

Here is a link that might be useful: Save Duke Gardens

One of my favorite gardens in this area is, like so many of
you, Chanticleer. . .particularly because all manner of
dramatic changes are actually encouraged from year to year.
But the whole greater Philadelphia area has been dubbed "the epicenter of horticulture in the United States".....and I highly recommend checking out a book titled "A Guide to the Great Gardens of the Philadelphia
Region", where-in you'll find extensive details about more
than fifty fabulous gardens in that area. So far, I've only been able to cover about half of them, but the depth
of the collection just leaves you breathless. . .and feeling mighty lucky to be living right next door.

Two little-known, but quite wonderful gardens that I enjoy
in central Jersey are Sayen Gardens (Hamilton) and Leonard J. Buck Garden (Far Hills).

Then there's New York - and I don't mean the State, but the
City. Only because I lived in Manhattan for many years (as
a gardener) did I discover the incredible wealth of gardens
there. The obvious choices are the New York Botanic Garden, the Brooklyn Botanic Garden, and, maybe my favorite, Wave Hill, up in Riverdale (The Bronx) high over
the Hudson River. . .but then there are all the unknown
gems: Rockfeller Gardens, just south of The Cloisters; the
relatively new, but stunning in it's location, the gardens
all along the Hudson Promenade in Battery Park City; or have you ever seen the spectacularly restored Conservatory
Gardens in Central Park (Fifth Avenue & 105th Street)?

Move on up the Hudson Valley and it's just one stunning
garden after another. . .but I think I can settle on my favorite as Stonecrop Gardens (Cold Spring), the home of
the Garden Conservancy.

Is it possible to have one favorite garden ???

Carl