The Deva and Pruning of the Extravagant Lilac

In season, lilacs are an extravagance of color and fragrance — especially when you have something like 437 plants, representing 138 different species and varieties, as the New York Botanical Garden does in its Burn Family Lilac Collection.

After they finish blooming, though, lilacs can present an extravagantly messy aftermath, nudging the gardener to intervene in the name of tidiness.

Get out the shears (hint: the long-reach version with a telescoping handle is especially helpful for such an assignment). Sharpen your powers of observation as you head out for duty, too, said Melissa Finley, the botanical garden’s Thain curator of woody plants. Deadheading may be the obvious task, but there are subtler clues to discover about fine-tuning your shrubs’ performance — or maybe extending your lilac season and its color palette.

The five-acre Burn Family Lilac Collection is part of what Melissa Finley, the New York Botanical Garden’s Thain curator of woody plants, oversees.

Ms. Finley is always applying that kind of careful eye to the garden’s historic collection, an entire lilac-forward world on fiveacres first planted in 1949 and renovated in 2016.

Some of what she’s looking for: Which older plants have grown leggy and need to begin a rejuvenation cycle starting late next winter? Are there damaged stems or signs of last season’s handiwork by pests such as lilac borer?