'Tis the season for pretty purple flowers.

'Tis the season for pretty purple flowers.

'Tis the season for pretty purple flowers.

All things green.
April 16 2007 2:07 PM

The Lilac Tide

'Tis the season for pretty purple flowers.

Click here to read a review of First Flower, a new NOVA documentary on the discovery of the world's oldest flowering plant. Click here for the latest installment of Slate's guide to planting a beginner's garden and here for previous installments.

Lilac bush. Click image to expand.
A lilac

Drive by farms in the northern tier of the United States and much of rural Canada, and you'll see groves of lilac bushes next to outhouses. Or, more probably, next to the places where outhouses used to be. It was a common practice to put lilacs by the privy, though the flowers with the helpful mitigating scents lasted only about two weeks.

A thrifty farmer would plant only a couple of lilacs at first, but those tough bushes sent out little side shoots to eventually make a grove that lasted long after the farmer's family moved away or got indoor plumbing.

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Lilacs are still tough, willing to multiply, uncomplaining through snow and ice, and, best, they equal spring. In Victorian poetry, spring itself was known as Lilac Tide.

For the cold-winter places where they grow best, those billowing clusters of fragrant flowers bear the very welcome message: It's not going to snow any time soon. Our common lilac, native to mountainsides in southeastern Europe, was brought across the Atlantic in the late 17th century. The Latin name for the classic lilac is Syringa vulgaris (vulgaris meaning simply common, rather than unrefined or, perish the thought, obscene).

A lilac bush was usually the only shrub in Colonial front yards. Beloved and historic though they are, lilacs have some drawbacks. They're not the shapeliest of bushes. When the flowers are done, you're left with kind of a green blob in the landscape. By midsummer, most lilacs get mildew—gray-white powder—on their leaves. (Not pretty, but it doesn't seriously affect the plant.)

They're not particularly interesting in winter, either—no striking bark or impressive form. So, though you'd like your fragrant lilac in the dooryard, as in the Walt Whitman poem, it's better to plant it somewhere it can fade into the background when the flowering is over. (Lilacs make a nice backdrop for shrub roses. Emerging creamy-yellow roses look great in front of fading dark-purple lilac flowers.)

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Lilacs are often the shrub that comes with the house, overgrown, with what flowers there are blooming way above nose-level. You need to whack a few of the oldest stems to the ground each year (right after flowering and before July 4) to encourage vigorous, flower-producing young stems. The worst drawback is to have the green blob but no flowers. "Why isn't my lilac blooming?" is one of the most common queries to garden advice columns. Usually the answer is: not enough sun.

You may have to be patient. Lilacs hold off blooming for two or three years after transplanting. Another possibility is that the bush may be producing lots of leaves rather than flowers because it has gotten too much nitrogen. Could be your lilac sits at the edge of a heavily fertilized lawn.

But the drawbacks don't mean it's hard to grow, and the scent is worth a lot. Lilacs will bloom their heads off if you give them the three things they need: sun, soil that's not soggy, and space. They need fully six hours a day of sun to bloom well, according to Daniel K. Ryniek, curator of the lilac collection at the Brooklyn Botanic Garden and past president of the International Lilac Society. The society's motto: A Lilac in Every Garden the World Over. (Click here for a list of notable lilac collections.)

To avoid sogginess, make sure your lilacs, which you can plant in spring or fall, have soil with plenty of organic matter and that they're on a site where water doesn't collect. (They're good on the side of a hill.)

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After planting, give them a large circle of mulch, 2 inches deep. This conserves soil moisture, smothers weeds, and, even more importantly, makes it less likely your shrub will get nicked by a mower (diseases or pests get in through the wounds). Water young plants once a week in dry periods for the first year.

For adequate space, plant the bushes at least 8 feet apart. This may seem ridiculous when you've just gotten that tragically small little bush home from the nursery, but most lilacs spread out about 8 feet. Plenty of space will mean your bushes get good airflow, which prevents mildew.

There are close to 2,000 named lilacs to choose from—from dark purple through magenta to lavender, white, and even a yellowish one called "primrose." Ryniek's advice is to visit a lilac collection and see what you like, or go to a nursery when they're blooming.

A Frenchman named Victor Lemoine churned out hundreds of hybrids of Syringa vulgaris at his nursery. Starting in 1878, he introduced lilacs with names that sound like Parisians at a party in Marcel Proust's Remembrance of Things Past—"Hippolyte Maringer," "Maurice de Vilmorin," "Marie Legraye" (a great white, some say the best), and, naturellement, "Mme. Lemoine."

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An avalanche of variations on lilac species native to China, Korea, and Japan joined the common lilac and Lemoine's hybrids in European and American gardens at the end of the 19th century. They're generally shorter, with smaller flowers and leaves, than the common lilac from southeastern Europe. "Miss Kim," a Manchurian lilac, has been a big hit in part because it doesn't get much above 5 feet tall and can bloom without a cold winter. "Miss Kim," lovely though it is, has a much lighter fragrance than the common lilac. Some would say subtle; I'd say disappointing.

Ryniek, at the Brooklyn Botanic Garden, says his favorite is whichever one is exuding at the moment. But he did mention "President Lincoln," a lilac-blue, which he likes combined with "romance," a single pink. I am curious about "Blanche Sweet," a pink lilac named for a silent film star who was slated to be the heroine of The Birth of a Nation until D.W. Griffith gave the part to Lillian Gish.

Shrub specialists, who get more excited about an unusual leaf than about a flower, recommend Syringa laciniata, the "cutleaf lilac." It has fragile lavender flowers that give a misty effect, and lacey leaves that don't get mildew.

Tall kinds of Syringa, tree lilacs from Japan and China, have recently become hugely popular for city gardens and even as street trees. They're trendy but justifiably so—they withstand drought and polluted air. These gorgeously named creatures—"ivory silk," "China snow"—have attractive coppery bark for winter interest. The cream-white flowers come in late spring and are fragrant but, for some of us, not fragrant enough.

The late and very lamented Henry Mitchell, garden columnist for the Washington Post, was most fond of the old, common, sweet-scented purple. He wrote, "[W]ith plants as with people, we take beautiful old friends too much for granted, and cannot believe anything will ever happen to them."