Cut some long stalks and bunch together and tie or secure with a piece of string or elastic. Place in a large paper bag with stems out. Just put away for a couple of weeks until the plants are dry and crispy and remove the green from the stems and store in a bottle. You will find the catnip keeps much better in a glass jar than in plastic.

The best catnip I have every found that grows into beautiful shrubs quickly comes from Richters.

http://www.richters.com/