Cool your Sonoma garden with all-white blooms

It’s said that white flowers lend a cooling aspect to a garden during hot summer days. It may be hard to envision those hot days right now, but you know they’re coming. With climate change raising the temperature in California, it may well be time to plan for a cool, shady corner for your garden or dress your doorway with white flowers as a sort of refreshing visual airlock between indoors and out.

Now, in January, when the ornamental plant catalogs are hot off the presses, it’s time to fantasize, plan and order what you’ll need to bring this concept to reality and plant your dormant choices.

For some inspiration for your white garden, turn to the most famous white garden in the world: Vita Sackville-West’s lovely version at Sissinghurst Castle in southern England. She developed it between 1950 and 1953, and in her plans, she imagined “a low sea of gray clumps of foliage, pierced here and there with tall white flowers.” She undertook the project as an experiment to see if it was possible to design a garden devoid of color.

What materialized is a masterpiece, a romantic moonlit landscape all in white, haunted by the round white faces of hush-winged barn owls.

Roses, dogwoods

Whether for a cool look or the romance of white flowers glowing in the moonlight, start planning your garden with two can’t-miss mainstays that just love our Sonoma County climate.

The first is one of the most popular roses on the planet: Iceberg. This floribunda has it all, starting with profusions of pure white double roses on its four-foot-wide and three-foot-tall shrubby frame. It needs full sun during the day and will be a knockout at night. It blooms from late spring to early fall. Give it regular water and prune it in winter, when it’s dormant. Best of all, if you want it to grow long and tall, over a trellis or doorway, you’ll find Climbing Iceberg available at garden centers, nurseries, in catalogs and online. It reaches 12 feet or higher.

There are hundreds of white roses available, but among the best (meaning low-maintenance and lots of bloom over a long season) are Claire Austin, Wedding Day and Mme. Alfred Carriere. This last one is a very double, sweetly fragrant, noisette rose with a hint of pearl pink in the center of its white blossoms.

Put the roses along pathways, toward the front of beds and borders, and place them here and there among other white-flowered annuals, perennials, shrubs and even trees. Just remember that for best bloom, all roses need full sun. If you have a fence, train a rose horizontally along its top rail and you’ll encourage bloom all along its length. Prune repeat bloomers when dormant. Prune June-only bloomers right after bloom.

Behind the roses, where kids and pets can’t get at them (because their foliage is poisonous), plant groups of the white-flowered sport of oleander. You’ll get masses of white flowers and a plant that needs hardly any maintenance, even during summer drought. If you do need to shape it, wear protective gear.

Trees form anchors in any garden, as they do for a white passage. An ornamental pear — Pyrus salicifolia ‘Pendula’ — is a breathtaking sight if given full sun. When in bloom, it looks like a fountain of white stars.

It’s worth searching for the hybrid dogwood known as Eddie’s White Wonder. It’s a cross between the native Pacific Northwest dogwood and Cornus florida of the eastern woodlands. It has hybrid vigor, grows taller than most dogwoods, has extra-large white blossoms and makes the perfect understory tree, shaded by taller deciduous trees.

The Japanese native Pittosporum tobira, commonly called the Japanese mock orange, makes a thick hedge that needs pruning to keep it within 10 feet tall. It can produce scads of waxy white flowers with a sweet scent. There’s a cultivar with variegated leaves. They’re drought-tolerant.

Both the large tree Magnolia grandiflora with its great white flowers with thick petals or the more compact Magnolia stellata with its floppy white stars about three to four inches across are welcome in any white garden.

The white trumpets of the tropical morning glory, commonly called moonflower, are a fascinating sight in the night garden. They are grown as an annual in regions of cold winters, but here in Sonoma County they’ll winter over as the perennial vine that they are. Another vine that’s strikingly beautiful is Wisteria floribunda ‘Longissima Alba’ that hangs two-foot-long panicles of white florets in stunning displays in spring. Plant it where you can reach it with your nose, for it has a honeyed scent.

Shrubs, ground cover

Among shrubs, Hydrangea grandiflora is a white-flowered candidate, along with white hibiscus, white camellias and a newly introduced white lilac, New Age.

Here are some perennials to use to fill in around the larger woody plants: Shasta daisies, Baby’s Breath (Gypsophila paniculata), white lilies, white scabiosa, white chrysanthemums (the botanical name has changed to Leucanthemum but most people still call them mums), white datura’s hanging trumpets, white-flowered clematis and white peonies.

For ground cover, here’s the lowdown on how to brighten the down-low areas: plant Lamium maculatum Beacon Silver, alyssum and white-flowering liriope, or any one of these.

If anyone asks why you’ve planted a white garden, say white represents reverence, humility, purity and innocence. But don’t tell them about Vita.

Jeff Cox is a Kenwood-based garden and food writer who can be reached at jeffcox@sonic.net.