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What Blooms When: A Calendar

What do garden designers have that you don't? A bloom calendar. We correct that deficiency here with a guide that can be used as a design tool, ensuring that the plants you buy this spring will bloom together or in sequence, as you please. Armed with the information, you can assemble a garden worthy of a glossy shelter magazine or simply know when a flower that takes your fancy will do its thing.

The schedule shows just when 50 favorite bulbs, perennials, shrubs and trees are supposed to flower – and brighten the months ahead. Annuals aren't on the list because most gardeners can get them to bloom throughout the warmer months. What the calendar tells is what will bloom together, allowing you to try color effects and combinations during the prime weeks of bloom, from now through August. It will help too in sequencing, so that a given bed can be designed either to be colorful all season long or just at points along the way. (If you are away for most of August, you may not want to plant crape myrtles and black-eyed Susans, which bloom then.) (continued below)

Also, remember that although some plants boom for long periods – for example, lavender, roses and veronica – others produce a main flush of flowers at first, followed by a far less showy recurrence. These and a few precious plants that display their colors at high revs for weeks, such as Russian sage, bee balm and coreopsis, offer the most bang for the buck. They impart almost the same floral abundance as annuals with less of the recurring expense and fuss.

Also, the bigger the plant, the showier the display. This is a generality, obviously. A flowering crab apple has more floral ornament than a tulip poplar many times its size. But you will need a lot of creeping phlox to match the blossom effect of a single crab apple, something a flower chart can't convey.

Permit us a little hedging. Predicting when plants will bloom is easier than forecasting the weather, but not by much. The exact period can vary widely from year to year in the same garden. Variables include the constant flux of temperature, rainfall, soil condition, encroaching shade and even past pruning habits.

Just as the average person doesn't exist, in the garden a "normal" season is normal only in our minds: No two dates are identical from year to year. For example, the Yoshino cherry trees around the Tidal Basin peaked on April 18 in 1958 but on March 15 in 1990, according to the National Park Service. The average date is April 5.

In addition to annuals, ornamental grasses are not in the calendar but should be considered, particularly for their presence in July and August. Their blades and plumes become ornamental in July and remain so until November, or through the winter, depending on variety.

The principal sources for the calendar are records kept by Lyle Priddy, curator of the perennial garden at Bon Air Memorial Garden in Arlington, as well as records from the Virginia Native Plant Trail at Green Spring Gardens Park in Alexandria.

Other sources include Barbara Bullock, curator of the azalea collection at the U.S. National Arboretum; the University of Kentucky cooperative extension service; the state arboretum of Virginia; the National Park Service; and our own observations over the years.

Finally, the gardener who relies on flowers alone for interest and beauty will be disappointed. Plants should be considered for the textures and shades of their leaves, the appearance of berries, seed pods and cones, the decoration of the bark and the beauty of the winter silhouette. But you've heard that spiel here before.

The flowering months are at hand. Take time from your schedule to enjoy ours.

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© Copyright 1999 The Washington Post Company

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