Gardening
Renting a garden plot
Community garden plots are available for rent by Rockville residents and non-residents. The 20 by 25-ft plots are located at Wootton's Mill Park on Hurley Avenue in Rockville and can be used from April 1 through mid-November.
A Local Source of Native Plants
A fabulous local source of native plant species (and information about them) is Dr. Sara Tangren's Chesapeake Natives, which "exists to protect, propagate and promote plants native to the Chesapeake watershed."
Which Plants are Native?
The Maryland Native Plant Society has posted lists of native species and growing suggestions by area online. Rockville is part of the Piedmont region, with the relevant information in a PDF file here, and a nicely categorized list of plants here. The Maryland Native Plant Society has this to say about planting native species:
Why Use Native Plants?
"Native or indigenous plants naturally occur in the region in which they evolved. They are adapted to local soil, rainfall and temperature conditions, and have developed natural defenses to many insects and diseases. Because of these traits, native plants will grow with minimal use of water, fertilizers, and pesticides. Wildlife species evolve with plants; therefore, they use native plant communities as their habitat. Using native plants helps preserve the balance and beauty of natural ecosystems."
Propagating Native Species
(Posted March 25, 2007) A couple weeks ago, I went to the Rockville Environment Commission meeting and heard a speaker from the Potomac Conservancy, an organization which "Since 1993, has been protecting the health, beauty, and enjoyment of the Potomac River and its tributaries." 
Specifically, the guest speaker was presenting the Growing Native project, which encourages educators and others to lead groups in the fall to gather seeds of native hardwood trees. The collected seeds are sent to state nurseries to be grown and used for restoration and reforestation purposes. The message I came away with was how important native tree species are to the health of riparian buffers, the forested area next to a stream which helps minimize damage from stream erosion and keep the aquatic life in the stream healthy.
In addition to fall seed collecting, Growing Native sponsors local tree-planting sessions in April and encourages public participation.