At one time, Groundworks published an e-newsletter called eGleanings, which offered seasonal information on a variety of plants. Clicking on the name will direct you to a .pdf file.
Early April 2011 (Gold Tide Forsythia)
April 2011 (Roses)
Early May 2011 (Baptisia Carolina Moonlight; soil building)
May 2011 (Creating mixed borders)
Late June 2011 (Daylilies)
August 2011 (Chrysanthemums)