Summer--Think Flowers!

May 13, 2016


Bringing some cheery summer color to your garden is fun and easy. Your favorite nursery, garden center or farmers' market can give you a head start with six-packs and four-inch pots of summer annuals and flowering perennials. Healthy, blooming (or almost-blooming) flowers can change the tone of a porch or deck in a moment.


Pair cool pink and warm coral impatiens with deep blue lobelia to brighten up hanging baskets or pots on shady porches. My summer favorite is a solid bed of cobalt-blue lobelia, providing a cool visual oasis on hot days.  


For a different look, azure-blue fountain lobelia produces cascades of flowers on bright green foliage for window boxes and pots. The softer ‘Cambridge Blue' lobelia adds to the palette of summer blues. Bright white and deep cherry-colored lobelia offer even more shade choices for our hot Napa Valley summers.


Choose healthy young plants that are not root-bound and still have some unopened blossoms. With good potting soil, an occasional feeding with diluted fish and kelp emulsion, daily watering and regular deadheading or pinching, lobelia and impatiens will provide color until autumn frost.


Consider colorful but flowerless foliage for shady spots. Light-colored coleus, in all its riotous combinations, grows larger leaves in lightly shaded areas. Leaf color ranges from pink and cerise to salmon and chartreuse. Plant a single coleus in a pot for living art, a whole bed in one dramatic leaf color combination, or a chaotic yet harmonious mix of many varieties.  


This year I am experimenting with climbing vines. Climbing Black-eyed Susan (Thunbergia alata) has blossoms like regular bushy Black-eyed Susan but grows five to six feet, quickly covering fence posts and pillars. With fuzzy green leaves and bright yellow-orange daisy-like blooms and big black centers, these vines will, I hope, climb up and cover my front-porch pillars. We are dragging the rocking chairs onto the porch and waiting for the show. Another plus: the blossoms are attractive to butterflies and other pollinators.


Another old-fashioned vine I am planting for the first time is cardinal climber (Ipomoea x multifida). This prolific vine can grow up to 20 feet in one season, completely covering a fence or trellis with five-fingered green leaves and deep-throated cardinal-red flowers. My expectation is that cardinal climber will cover a plain fence and tempt our pollinator friends.   


In large or small plantings, white, lavender or pink alyssum will soften and blend areas of color while its sweet honey scent attracts bees and other pollinators. Pair velvety deep-purple petunias with knee-high yellow, orange and red butterfly cosmos for a cheerful porch view or walk.  


Carnations, Sweet William and the old-fashioned plants known as pinks, all members of the Dianthus family, can be transplanted now for fragrant cut flowers later. You can also sow or transplant sunflowers (Helianthus annuus) this month. They range from knee high to as tall as an elephant's eye, so you have plenty of choice.


If you have a little space and more time, sow seeds of some flowers now, then again in a month or so. This staggered sowing will produce blooms from early summer until the first frost. In a sunny patch, weeded and watered, try some cheery cosmos or warm-toned marigolds (Tagetes). The ethereal blue love-in-a-mist (Nigella) is also a speedy grower; sow it successively to extend the bloom time. Enjoy the whimsical flowers, then the papery pods and flavorful seeds.


For hot, dry areas, four o'clocks (Mirabilis jalapa) are amazing. Also called marvel of Peru, four o'clocks have large, black bead seeds and bright blossoms in deep pink, sunny yellow, snowy white and carnival stripes. These two- to three-foot plants can survive in the cracks between concrete if they get off to a strong start with spring rains or an attentive hose. Four o'clocks hit their stride in the late afternoon and evening, when their distinctive fragrance wafts through the garden.


Zinnias (Zinnia elegans) win for splashy summer color and endless color choices. Tiny ‘Thumbelina' zinnias in soft pink, yellow and orange are perfect for small pots and pathway borders. Consider ‘Moulin Rouge', a selection of three different tall reds; the popular chartreuse-green ‘Envy';' or the mixed circus colors of ‘Cut and Come Again'. And here's the wonderful thing about zinnias and so many summer flowers: the more blossoms you cut, the more they will grow.


Workshops: U. C. Master Gardeners of Napa County will conduct a workshop on “Home Composting” at American Canyon Senior Center, 2185 Elliott Drive, on Wednesday, May 18, from 6:30 p.m. to 8:30 p.m. Learn the basics of backyard composting and how to turn your yard waste and kitchen scraps into a rich soil amendment or mulch. Learn about tools, techniques and bin types. Register online at Or pick up a registration form at the Master Gardeners' office (address below). No phone registration. Directions will be sent when your registration is complete.

U. C. Master Gardeners of Napa County will conduct a workshop on “Growing Ornamentals and Flowers” on Saturday, May 21, from 10 a.m. to noon, at Mid-City Nursery, 3635 Broadway, American Canyon. Learn about the maintenance and care of ornamentals. Master Gardeners will discuss hydrozoning, how to plant for seasonal color year round, and how to encourage pollinators in your garden. On-line registration (credit card only); 
Mail-in/Walk-in registration (cash or check only). 

Master Gardeners are volunteers who help the University of California reach the gardening public with home gardening information. U. C. Master Gardeners of Napa County are available to answer gardening questions in person or by phone, Monday, Wednesday and Friday, 9 a.m. to Noon, at the U. C. Cooperative Extension office, 1710 Soscol Avenue, Suite 4, Napa, 707-253-4143, or from outside City of Napa toll-free at 877-279-3065. Or e-mail your garden questions by following the guidelines on our web site. Click on Napa, then on Have Garden Questions? Find us on Facebook under UC Master Gardeners of Napa County.