Copper Canyon daisy

Gardeners, like farmers, take more than a passing interest in the daily weather report.
Planting will not be scheduled for a weekend when hot or windy weather is forecast; such conditions may shock young plants and make garden acclimation difficult. Overcast skies, on the other hand, while not propitious for beachgoers, are advantageous to those who find happiness in nestling young plants, fresh and shining, into a new garden home.
The weather at one time of the year also may have a significant influence on the behavior of plants several months later. The substantial rain we received this winter will mean a greater-than-usual display of flowers this spring and summer; when it rains, salts that inhibit flowering are leached out of the earth. In any year, the spring bloom of fruit trees and lilacs is enhanced by a cold snap the previous winter.
Weather and cultural conditions during summer and fall may influence the performance of winter flowering plants. Last summer, for example, was hotter than usual. If your azaleas were stressed – if too much time elapsed between deep waterings – they soon will tell you so by the sparseness of their spring bloom.
Not long ago I wrote about the shrub marigold or Copper Canyon daisy (Tagetes lemmonii), a winter flowering perennial with a sweet fragrance. I counseled against planting it in full sun
because it had never flowered for me – in Woodland Hills – when given that exposure. When exposed to morning sun alone, however, it flowered abundantly.
Ann Millage, a reader from Tujunga, writes that her experience has been ”exactly the opposite. This plant makes for stunning winter color planted in full sun on the crest of fast-draining granitic slopes. Plants in morning sun have maybe 20 percent total bloom count in comparison. I wonder what accounts for our radically different experiences.”
I believe the difference may be attributed to climate, which is milder in Tujunga than in Woodland Hills. Tujunga’s climate (Zone 20, as delineated in the “Sunset Western Garden Book”) is influenced by the ocean, unlike that of Woodland Hills (Zone 18). This means that winters will be slightly warmer, and, perhaps more importantly, summers will be somewhat cooler and moister – a bit more humid – in Tujunga. Full sun in Tujunga is not as harsh as full sun in Woodland Hills.
Shrub marigolds – which grow twice as large in Central America as in Arizona – apparently may be stressed by summer heat and dryness to the point where they do not flower the following winter.
Incidentally, the Los Angeles County Arboretum (Arcadia), Descanso Gardens (La Canada) and Huntington Gardens (San Marino) have the same climate as Tujunga; it is a climate that invites a diversity of plants to flourish.
E.L. Andre, a reader from Sherman Oaks, chastises me for not pointing out the disadvantages of the plants I discuss, admonishing me to “tell all the truth.”
Actually, the truth is that any plant can fail to grow for a variety of reasons, but most often the trouble can be traced to what happened at planting time. Either the plant was put in the wrong place (too much sun or shade) or the soil was not broken up or amended sufficiently, or the planting hole was too narrow or too deep, or not enough mulch (it should be at least three inches thick) was layered on the soil surface.
Specifically, I am taken to task for extolling the praises of succulents – such as Sedums – which, for Andre, always attract snails and slugs. Funny, I have never seen snails and slugs among succulents I have planted. But then this same reader considers Gardenia jasminoides “Veitchii” an easy plant to grow, and I have never had much luck with gardenias.
As in the case of the shrub marigold, two gardeners can have radically different experiences with the same plant. Conditions for growth – especially in climate, sun exposure and soil type – can differ significantly over short distances, with corresponding differences in plant performance.
Weather at any given moment may indicate how plants will grow later in the year, but plant performance also can be a way of predicting the weather. An entire science, known as phenology, is devoted to the relationship between cyclical biological phenomena and climatic or weather conditions.
“The principle,” notes garden writer Eleanor Perenyi, “consists of noting when plants known as ‘indicators’ burst into leaf or bloom. Given this information, it is possible to predict other events like the warming of the soil, the likelihood of one area remaining colder than another, and so on. The common lilac, for instance, won’t open its flower buds until it is safe to do so, and the farmer or gardener who takes phenology as his guide will watch for this flowering – rather than go by the books and perform certain tasks at a fixed date.”
Phenology explains why record keeping is important to successful gardening.
Tip of the week: Sun Spray is a mild, paraffin-based horticultural oil that is not toxic to plants (as opposed to dormant oils than can burn foliage). It is a contact insecticide that kills mealybugs and scales by smothering them. Sun Spray can be used effectively on any sucking insect or its eggs, at any time of the year, on indoor plants, garden ornamentals and fruit trees.