Malibu Garden Column: Come What May

Homemade compost and bark mulching are great additions to rosebeds.

May in the Malibu garden is a time to enjoy the effects created by fall and winter planning, soil preparations, planting and pruning. It’s also a busy time for keeping plants shaped and growing properly. And it’s a great time to attend the Malibu Garden Club tour of four different displays of what can be grown and shown off in Malibu’s mild climate. The tour takes place May 15, 11 a.m. – 3 p.m. For ticket information call 310.457.3005.

May Rose Tips Remember that with every cut, the rose is being pruned and trained for its next production. Trim above the sprouting new growth stems and above the buds. Keeping branches from crossing and centers open are good rose cutting strategies, which will pay off with more blooms. For the climbers, tie the lateral new growth securely horizontally and the blooms will take off upward toward the sun. Keep the roses on an even, organic feeding schedule. Use blood meal and bone meal or commercial rose food. Read and follow labels. Homemade compost and bark mulching are also great additions to rose beds.

May Additions Which plants to choose to add shapes or color to replace winter blooms will depend on the desired effects. If the garden is to look like a high sierra or Santa Monica Mountain wonderland, add lupine, California poppies, Indian paintbrush and columbine (try the native Aquilegia Formosa). If water conservation over the summer months is the foremost concern (and it should be a concern for every gardener) try shrub-like flowering penstemon, gaura (perennial native) and native salvia spathacea, hummingbird sage.

For an exuberant, cottage garden effect, don’t prune off blooms until they are really spent, then dead head. Keep the lines soft and the pathways curving. The chrysanthemum family includes the productive c. maximum or Shasta daisy, the hardy Dusty Miller, c. ptarmiciflorum, as well as feverfew, c. parthenium. The salvia family includes the prolific salvia leucantha or Mexican sage, which is high on my list of plants that will perform all summer in the Malibu sun with little care except to be cut back. Other additions to flower displays for summer include alstromeria, hemerocallus, nemesia, nicotiana, penstemon and scabiosa. Petunias brighten up beds and come in a wide assortment of colors. For the hottest spots, marigolds, sunflowers and zinnia add summer brightness.

Bug of the Month-the Aphid When the rose stem is tripled in size and the bud is covered with green or red sucking bugs, it’s time to pull out the stops against the rapid reproducers: the aphids. There are more than 200 aphid species ranging in size from one-sixteenth to one-quarter inch, colored either green, red, black and in between. Some have wings, most don’t. Females are born able to reproduce live young within two weeks. The aphid finds its strength in numbers and accomplishes its damaging effects by rapid and prolific reproduction. Aphid populations will be highest in plants with high nitrogen levels, sometimes caused by overfeeding with nitrogen rich foods.

Natural enemies include ladybugs, lacewings, and the syrphid (aka flower or hover) flies and birds. Encouraging these insects through integrated pest management systems is a smart gardening tactic. Conside giving a portion of the garden to plants that encourage the beneficial insects. These plants include laminiaceae, in the mint family and brassicaceae, in the cabbage family. Let herbs, like parsley and mint, go to flower to attract the insects needed.

Aphids ingest or “suck” plant juices and excrete a honeydew-like, sweet sap through two tubular projections at their posterior (known as cornicles). The sweet excretion attracts ants. Thus the ant-aphid cycle, which taunts many backyard gardeners. Another problem caused by aphids is the sooty, black mold, which forms on the backs of leaves and which cuts the light available for healthy plant growth. Lowering the populations through biological controls will cut the sticky honeydew and the subsequent black mold.

When aphids appear in great numbers on rose buds, defense can be initiated with hard spray of hose water-however, the pressure needed to rid the plant of the suckers can often damage the buds. Try homemade concoctions of Dr. Bronner’s or other soaps and water. Eventually, if the aphids persist, use sprays containing Neem oil (from a nut). These can be purchased as “Rose Defense” or “Safer.” One problem with broad-spectrum insecticides can be that natural predators-lacewings, ladybugs and birds-can be eliminated in the process.

Design Tip of the Month Whatever you plant, plant en masse. At least create a drift or swath of one plant or color. The word swath actually derives from the width of a scythe used in mowing. Make a statement with your plant choices.

Next month: garden color through foliage and more on encouraging beneficial insects. E-mail garden questions to be answered in this column to or call P.M.Harris Landscape Design at 310.581.7956.