Galloping Groundcover

The Mexican primrose is just beginning to be noticed. For years, it was mysteriously absent from local nurseries as if there were a conspiracy against it. It deserves wider recognition, since it is among the most care-free, floriferous, sun-loving summer ground covers. It spreads quickly and requires little water once established. Its flowers are pink. As Richard Angelo of Northridge once told me, it does quite well planted under white “Iceberg” shrub roses. Horticulturists such as Ronette Simon of Sherman Oaks and Robert Wallace of Canoga Park have planted the Mexican primrose and recommend it.
Two types of primroses are seen in Los Angeles: the fall/winter primroses and the spring/summer primroses. There are primroses that we plant from Thanksgiving through Valentine’s Day for color in the shade. These are the Primula species of primroses, whose habitat stretches from Iran to China – the polyantha primroses (whose flowers are bright pink, yellow, blue and red) and the obconica and malacoides primroses (which bloom in lavender, pink and salmon). Then there are the primroses that we plant between Mother’s Day and July 4. These warm-weather primroses are the Oenothera (pronounced “ee-NOTH-er-a”) primroses, including the Mexican primrose (Oenothera Berlandieri) and the evening primrose (Oenothera Hookeri), which are native to Mexico, California and the Southwest.
Summer primroses
The summer primroses, perhaps because they grow so effortlessly and are easily started from seed, have not been seen much in nurseries until recently. Some people consider primroses to be weeds on account of their aggressive growth. However, although the plants spread quickly, they can be kept under control by hand-pulling and are not nearly as invasive as ivy or Hall’s honeysuckle, for example.
Flowers known as primroses are supposed to bloom early in the season – prim comes from prime or primary – and resemble roses. In Europe, where they received their name, our fall/winter primroses are among the first flowers to bloom in the spring. The Mexican and evening primroses, on the other hand, are among the first flowers to bloom in the summer. Actually, by May, the Mexican primrose will already be growing quite well, and its plethora of pink flowers serves as a reminder that the number of daylight hours has increased.
The evening primrose has butter yellow flowers that are visible now. This California native really can become a weed if steps are not taken to reduce its seedling population from year to year. However, it makes an excellent naturalizing plant for dry, sunny slopes – plant it together with the Mexican primrose for a summer parade in pink and yellow.
These summer primroses disappear from sight when the weather turns cool in the fall but come back with complete reliability as the weather warms.
Verbena and lantana
Two ground cover types, both in the Verbenaceae family, can compete with the primroses in terms of their summer flowering potential in full sun: the verbenas and the lantanas. Verbena peruviana has long been grown – its cultivars are violet, lavender, purple, red and pink – as a trailing perennial. Verbena bipinnatifida, which self-sows, has intricately laced leaves and violet flowers. The recently introduced Tapien verbena from Japan grows absolutely flat upon the ground and, in its prime, appears as a mat of solid violet-purple. “Homestead,” a deep violet Verbena cultivar, has the longest, fattest flower clusters of all.
Lantana montevidensis is a trailing plant with lilac-colored flowers. It also has a white cultivar that is planted with increased fervor from year to year. These lantanas attract honeybees and are sensibly planted around vegetable gardens or orchards where such pollinators are desired.
Tip of the week: I owe a debt to Robert Wallace for demonstrating a hand-held magnifier with a battery-charged light that makes it possible to identify tiny garden pests, such as mites, that would otherwise escape notice. This instrument, which magnifies the viewed object by 30 times, can be obtained at hobby shops or through the Internet (search under “30X magnifier”) for $12 to $15. Not only will the microscopic insect world come vividly to life for you and your children, but the fine anatomy of leaves, stems and flowers will be revealed as well.

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