Wonderful article, Margaret. Thanks for posting! I have been to Sissinghurst, but did not spend the night there. Gorgeous gardens.
The county of Kent, to the south of London, is a great area to visit for gardens and country houses. The article has left out one of the best. Hever Castle, 30 minutes to the south of London, was the home of the Boleyn family and Anne Boleyn, second wife of Henry the 8th. Hever has beautiful gardens, and especially is known for its rose garden. You can stay on the property in beautiful cottage quarters behind the house. I have visited Hever several times, but have not stayed there overnight. Easy to reach from London by train. There is an excellent cafe.
http://www.hevercastle.co.uk/
Nearby is the country home of Winston Churchill, Chartwell, in the village of Westerham. One can visit Mrs. Churchill's gardens, and the greenhouse, where Winston Churchill sat to do paintings of all types of flowers. Many of his paintings are on display throughout the house. I enjoyed my visit here because I got to see some of his paintings. You cannot spend the night there, but there is a cafe.
http://www.nationaltrust.org.uk/chartwell/