STOCKBRIDGE, Mass. — It's finally spring in the Berkshires and many local gardeners are back in the dirt bringing up daisies.

Alongside the arrival of gorgeous (and long-awaited) displays of tulips, daffodils and magnolia trees, the Berkshire Botanical Garden is also ringing in the arrival of the flower season by honoring the past and welcoming the future.

The garden is hosting its first annual Roy Boutard Day on Sunday, May 1, from 9 to 5, in honor of one of its most beloved directors, who served the horticultural community there from 1954 to 1984. In addition to this good old-fashioned celebration, the garden will also present "Out On a Limb: Architects Take a Bow," a seasonlong exhibition of six innovative treehouses by architects and designers including Michael Trapp, Joseph Cho and Stefanie Lew of binocular design, Robyn Sandberg, Gray Davis and Will Meyer of  Meyer Davis Studio, Mark Smith and Tim Smith of 9 Partners Design and James Odegaard.

Robin Parow, communications director for the garden, said the day promises to be one of whimsy, beauty and, of course, sunshine.

Roy Boutard was director of the Berkshire Botanical Garden for 30 years. He died last year at age 94.

"We're expecting great weather and that's the most important thing," Parow said in a phone interview. "We have six unbelievable, amazing treehouses and we are encouraging families with children to come and explore them. They can go in the houses and see for themselves. It's really almost magical what the designers have done with these treehouses."

Parow likens the exhibition to a scene out of Swiss Family Robinson. Each treehouse contains its own unique character, having been inspired by a city-dwelling mockingbird, Colonial outbuildings, roofscapes, childhood memories and a Japanese lantern, to name a few, she said. These innovative structures set against the backdrop of blooms and sunshine encourage visitors to play, plant and get inspired for the growing season.

"People are pining for something green at this point," she said. "All of our spring blooming bulbs are out, the magnolia trees are magnificent, this place is quite a sight right now. Having the Roy Boutard Day in conjunction with the treehouse exhibition is just so wonderful. Here we have this old-fashioned traditional touch complete with a reception and punch delivered in an antique bowl and then a flip into the 21st century with a two-story treehouse fortress and mockingbird nest. It's really kind of perfect."

The garden's Herb Associates, a volunteer group, will provide the traditional Mai Bowle punch (which is a forever-secret recipe) as well as cookies and refreshments at a post-tour reception.

Cecile Roy Boutard died July 1, 2010, at the age of 94. A native of Sweden, he came to this country from Canada in the 1950s after graduating from England's Royal Horticultural Society Gardens.

Boutard wrote a regular column on gardening for The Berkshire Eagle and had a gardening show on WBEC. Under his direction, the garden expanded its grounds and educational offerings and won numerous gardening awards.

The tour, beginning at 1, will highlight Boutard's favorite display areas and gardens to which he contributed to during his three decades as director. Of course, no honorary celebration of spring is complete without a graduation and according to Parow, the BBG's got it covered.

"We are going to have a graduation ceremony for our horticultural program," she said. "These people have put years into studying here at the garden and now they are finally going to be certified horticulturists. It's quite an accomplishment all the way around."

Admission to the garden on Sunday is free and the grounds are open from 9 to 5. The Roy Boutard garden tour will begin at 1, followed by a Mai Bowle and reception.