Winter is the BEST time for learning more about good gardening practices because that's when the public gardens are busy teaching. Check these out:
GREEN SPRINGS GARDEN, NO. VA.
Green Springs is known for their excellent programs; whole carloads have been known to schlep down from Maryland to partake. Here's the link.
BROOKSIDE GARDEN IN WHEATON, MD
Their "Green Matters" symposiums are great, and this year it's about water issues. Check it out - as well as their whole catalog of courses and workshops in the right sidebar.
LEWIS GINTER BOTANIC GARDEN IN RICHMOND, VA
Coming up Feb 4-6 is an awesome-looking and reasonably priced symposium on Gardening in the Age of Global Warming. Here's the agenda for that, and here's the schedule for a whole YEAR of great stuff (to celebrate their 25th anniversary).
KNOW OF OTHERS? Leave a comment and I'll add it to this list.
Posted by Susan Harris

Benny and others - The Seed Exchange is Sat 1/31 (always the last Sat of Jan each year that we had declared "National Seed Swap Day") - for a FAQ on the event go to:
http://washingtongardener.blogspot.com/
Posted by: Kathy J, Washington Gardener | 2009.01.30 at 06:57 AM
Where is the seed exchange held this Saturday? I would LOVE to attend!
Posted by: Benny | 2009.01.29 at 07:26 PM
For anyone one looking for more formal training towards a career in landscape design and/or sustainable landscapes, they should consider The George Washington University's Landscape Design Graduate Certificates or Master's degree. We hold information sessions throughout the year. Please visit our website for dates and more information.
Posted by: Mona Yep, GW's Landscape Design Programs | 2009.01.28 at 11:19 AM
Susan,
Thanks so much for the mention. It is going to be exciting to have Allan Armitage and Felder Rushing here in Richmond addressing Gardening in an Era of Climate Change. And what a great way to spend a cold winter day -- and remind us that spring is just around the corner!
Posted by: Jonah | 2009.01.13 at 10:13 AM
I would add to it the upcoming RootingDC on 2/21, our Washington Gardener Seed Exchange on 1/31, and the PVC-NARGS Conference on 1/31-21. There is also the Hort Society of MD's Design Seminar on 2/28.
Posted by: Kathy J, Washington Gardener | 2009.01.11 at 12:16 PM