Northern California May checklist

What to do in your garden in May
Julie Chai

Go shopping

Buy herbs, lavenders, and salvias Find an extensive range of culinary and medicinal herbs, 40 varieties of lavender, and 60 -varieties of salvias at Morningsun Herb Farm in Vacaville (707/451-9406). Enjoy the demo garden in full bloom along with food tastings at the farm’s annual open house on May 9.

Shop for kousa dogwoods These shrubs (which can be trained as trees) have delicate-looking flowers in late spring and stunning red fruit and foliage color in fall. Sara Monte of Wildwood Farm Nursery in Kenwood (888/833-4181) recommends these from its long list of in-stock kousas: white-bloomed ‘Angel Wings’, pink-flowering ‘Satomi’, and ‘Wolf Eyes’, which has cream-edged leaves.

Planting

• Back-of-the-border blooms Sunset climate zones 7-9, 14-17: For vertical accents in borders, grow tall, upright bedding plants behind shorter ones. Good choices include green-flowered Nicotiana langsdorffii and fragrant N. sylvestris, 'Aztec Sun' and 'Goldfinger' Tithonia, and tall-growing varieties of cosmos (such as the Sensation series) and sunflower. All grow 3 to 6 feet tall.

Grow a fragrant low-water shrub A scented greeting, familiar from year to year, at a garden seat or along a path boosts the spirits and draws us to the garden. Sweet-scented, white-flowered bush anemone (Carpenteria californica), a native that needs little water and care, ranks among the 100 tough and reliable plants chosen as Arboretum All-Stars by the University of California, Davis Arboretum. Find other scented shrubs on the Arboretum All-Stars website (arboretum.ucdavis.edu; click on “Arboretum All-Stars”).

• Ornamental grasses With their flowing habit, grasses lend a sense of movement to the garden. The following species are also drought-tolerant, take full sun to part shade, and thrive in Northern California (in zones 1-2, treat them as annuals): Elymus glaucus, E. triticoides, Festuca paniculata, and Pennisetum messiacum. If you can't find the plants locally, order from Greenlee Nursery (909/629-9045).

• Summer annuals  Zones 7-9, 14-17: May is the optimum planting month for annuals. In sunny beds, plant cosmos, Madagascar periwinkle (Vinca rosea), marigolds, nasturtiums, petunias, salvia, and zinnias, from either sixpacks or 4-inch containers. In shade, grow coleus and impatiens. Zones 1-2: Plant after danger of frost has passed.

Continue sowing salad greens Plant a small batch of seeds every two weeks until daytime temperatures reach 75°, when it’s too warm for these cool-season crops. To beat advancing heat, choose fast-growing arugula and leaf lettuce, rather than slow-maturing head-forming greens such as radicchio and romaine.

• Veggies for containers Zones 7-9, 14-17: If you don't have space to grow vegetables in the ground, plant them in containers. Tried-and-true favorites that do well in pots include 'Blue Lake Pole' beans (train them on obelisks), 'Giant Marconi' pepper, 'Early Girl' and 'Sun Gold' tomatoes, and 'Eight Ball' or 'Spacemiser' zucchini. Seedlings are available in nurseries now. Choose a container at least 18 inches deep and wide, and use fresh potting mix. Place the pots in full sun. Fertilize and water regularly.

Plant a bean tipi Gather twine, a packet of pole beans, and three to eight bamboo poles each 6 to 8 feet long. Arrange the poles in a circle and tie them together at the top. When the weather has warmed, plant the beans 6 inches apart, four per pole. Try classic varieties ‘Blue Lake’ and ‘Kentucky Wonder’; red-flowered scarlet runner; or yard-long beans (Chinese long beans), which have 2-foot-long pods.

Maintenance

• Aerate lawns Lawns that get a lot of heavy foot traffic may have compacted soil, making it difficult for water, fertilizer, and oxygen to reach the roots. If you can't push a screwdriver up to its handle into the turf, it's time to aerate. Use a manual aerator to punch holes in small lawns. Or you can rent a power core aerator from a landscape equipment supplier (look in the yellow pages under Rental Service Stores & Yards) or hire a lawn professional. Aeration works best on a moist lawn.

Thin fruit   Sunset climate zones 7-–9, 14–17: Before apples, Asian pears, nectarines, and peaches reach an inch in diameter, gently twist off enough fruit to allow 4 to 6 inches between remaining fruit. (Zones 1–2: Do this in early summer.) This improves the size of the remaining fruit, reduces the risk of broken branches, and keeps trees producing well annually rather than in alternate years. Master Gardeners at the Fair Oaks Horticulture Center in Fair Oaks (cesacramento.ucdavis.edu or 916/875-6913) will demonstrate fruit thinning at a free class on May 16. They also have detailed thinning info on their website.

Outsmart pests Control aphids Strip aphids from plants by hand or dislodge them with a blast or two from the hose.

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