The Lilac Collection has been getting its very own special day of celebration, Lilac Sunday, every Mother’s Day for the past 112 years. Flowering extends beyond this day, of course, running from the end of April to the beginning of June. Within 2 weeks of flower wilt, we begin preparation for next year’s spectacle by deadheading the lilacs. This practice helps to ensure that the shrubs do not expend more energy in seed production, but rather use it to produce flower buds more prolifically.

 Many hands make quick work of this time-sensitive task, as interns, seasonal gardeners, and horticulturists make their way through over one hundred plants. Some shrubs are so large that we need our six-foot extendable pruners to reach many of the spent flowers. Orchard ladders extend our reach even further, making it easy to maneuver in and around a shrub. Between plants, we spray sterilizing solution on our snips to prevent the spread of pathogens like phytoplasmas, often called Lilac Yellows. All the cuttings are collected and composted, to return to the collection as a soil amendment come the fall.


Approximate number of live lilacs in the Arnold collection.


Percentage of ethanol in the solution used to sterilize shears.

Conor Guidarelli is a horticulturist at the Arnold Arboretum.

From “free” to “friend”…

Established in 1911 as the Bulletin of Popular Information, Arnoldia has long been a definitive forum for conversations about temperate woody plants and their landscapes. In 2022, we rolled out a new vision for the magazine as a vigorous forum for tales of plant exploration, behind-the-scenes glimpses of botanical research, and deep dives into the history of gardens, landscapes, and science. The new Arnoldia includes poetry, visual art, and literary essays, following the human imagination wherever it entangles with trees.

It takes resources to gather and nurture these new voices, and we depend on the support of our member-subscribers to make it possible. But membership means more: by becoming a member of the Arnold Arboretum, you help to keep our collection vibrant and our research and educational mission active. Through the pages of Arnoldia, you can take part in the life of this free-to-all landscape whether you live next door or an ocean away.

For more tree-entangled art, science, and writing, subscribe to Arnoldia by becoming a member of the Arnold Arboretum.