What to do in your garden in December
Holiday greens. Nurseries are stocked with greenery - garlands, wreaths, and conifer swags - for adorning a door, gate, or wall over a fireplace. Spray untreated greens with an antitranspirant (also available at nurseries) to delay drying. Add cones and pods and finish the wreath or swag with a raffia bow or, for a more elegant look, a bow made from wired ribbon.
Camellias. Sunset climate zones 7-9, 14-17: To get the flower color you want, shop for Camellia sasanqua and early-flowering C. japonica now, while they're blooming. Sasanquas range from upright (good choices for informal hedges and containers) to spreading or vinelike (useful for espaliers and groundcovers). They also tolerate a fair amount of sun, except in hot, inland areas. Upright varieties include 'Apple Blossom', 'Setsugekka', and 'Yuletide'; two good spreading types are 'Chansonette' and 'Showa-No-Sakae'. Japonicas make attractive specimen plants and espaliers. A few of the many fine choices include 'Alba Plena', 'Daikagura', 'Debutante', 'Elegans', 'Nuccio's Carousel', 'Nuccio's Gem', and 'Wildfire'.
Perennial vegetables. Zones 7-9, 14-17: Bare-root vegetables are available in nurseries now. Set out roots of asparagus, horseradish, and rhubarb in well-tilled soil. Water well at planting time and in between rains.
Poinsettias. Nurseries are overflowing with poinsettias this month. Choose plants with healthy dark green leaves; avoid those that have been stored for more than a day or so in paper sleeves (which causes leaves to drop off). Indoors, display plants away from heater vents in a spot that gets bright, indirect light. Outdoors, put them under an overhang next to the house; temperatures below 45° to 50° can damage plants. Water when the top of the soil feels dry to the touch (never let the soil go completely dry). Two ways to display them: Cluster red and white varieties in a large basket. Or group several plants whose bracts (flowerlike leaves) come in an unusual color or pattern.
Primrose. Primula obconica is one of the showiest primroses you can grow; it bears large clusters of blooms above roundish, apple green leaves. But a chemical called primin, found on the hairs of its stems and leaves, can cause a skin rash in some people after they've handled the plants. If you're sensitive to primin, shop nurseries for Libre, a primin-free series of P. obconica. Flower colors include blue, magenta, pink, light salmon, and white.
Protect strawberries. For stronger plants and higher yields in spring, cover the plants through winter with floating row covers. Available at most nurseries, row covers are made from a lightweight, synthetic fabric, which protects plants from light frosts. If setting out new strawberry plants during the dormant season, select a sunny site where strawberries haven't been grown for several years to avoid disease problems; add plenty of compost. Apply a mulch on top of the soil.