Definitely go to the National Botanical Gardens, on the Mall, up close to the Capitol Building! Well worth it. Also, if you have time, be sure and go to Longwood Gardens, about 30 miles west of Philly. Down by Frederick, MD is an aquatic gardens, called Lily Ponds that is real nice. While in D.C., take a tour bus out to Pres. Washington's Mount Vernon - very nice period gardens - even have a couple Cedars of Lebenon on the estate. Those are the main ones I know about. Have a great time and let us know what gardens you discover that we don't list!

We are going to the Longwood Gardens in Penn. not far from DC. This garden is on 1,000 acres and is ofter referred to as the Dupont Gardens. A neighbor just returned from there and spent the entire day doing the garden tour. She loaned me the garden tour book. Our trip is planned in late August or early Sept. I can't wait.

Here is a link that might be useful: Longwood Gardens

The gardens at Monticello, the home of Thomas Jefferson, in Charlottesville, VA are awesome, as is the entire site. Also, on the trip there, you could check out Montpilier, the home of James and Dolly Madison, in the midst of horse country. However, due to the dreadful drought, our countryside will not show the best scenic conditions.

One of Washington's best-kept garden secrets is the National Arboretum in N.E. Washington. There's an entrance on R Street just off Bladensburg Road (I think: better check). Metro has just introduced weekend buses from Union Station (popular Red Line subway and train station) to the Arboretum. It's 400+ acres of all kinds of trees, flowers and shrubs. In spring, they're most famous for their exceptional azalea collection. They also have a fabulous bonsai collection and an herb garden that has all kinds of themed herb collections (colonial, pharmaceutical, etc.) Lots of ongoing exhibits and special shows from time to time, and a very nice gift shop on the premises. Check it out anytime of year.

I visited Hillwood in DC last month and it is well worth the trip if you can get tickets. Check out their website
(www.hillwoodmuseum.org). Also Ladew Gardens in Monkton MD just north of Baltimore. Brookside Garden in Silver Spring MD near the Glenmont metro stop.

Ben Lomond antique rose garden at Manassas, VA just outside
DC would be gorgeous in spring.

Also, I visit to Dumbarton Oaks in Georgetown should be on your list of gardens to see in D.C.
Shirley

I loved the gardens at Mt Vernon , and the beautiful gardens at TheNational Cathedral as well.The National Cathedralhas a web page, so you can preview the cathedral and gardens.

Can't believe no one's mentioned Dumbarton Oaks, in Washington (Georgetown area). It was designed by Beatrix Farrand, the first woman landscape architect in America, and is considered her masterpiece. Now owned by Harvard University but open to the public in the afternoons. Stunning. She designed not only the planted spaces but many of the architectural details in the "hardscape" (stonework, balustrades, etc.) Don't miss it.

I second (or third) Dumbarton Oaks--just a beautifully balanced sumptuous garden (and wonderful medieval collections in the museum as well).

Some others to give consideration to while in the Philly area are Winterthur and Chanticleer....both also spectacular next to that of Longwood Gardens (I worked and studied there for two years)...and I almost forgot Morris Arboretum!

A good website to check out for over twenty gardens in that area is http://libertynet.org/gardens

Hey you guys - it is Garden Week in Virginia beginning the week of April 20....I live in California and have attended twice - the whole state celebrates gardening the last week of April every year. There are tours in almost every town - tours of historic sites (all the major historic sites have a special garden day with special exhibits, things for sale, etc.) Also tours of private homes, plantations - both the homes and gardens. It is wonderful....there is a website and a guidebook that is available right now....here is the link:

http://www.vagardenweek.org/