Plants get head start on spring
As anyone knows, who has lived here in the Okanagan for a few years, the arrival of spring in this part of the world can be quite unpredictable. We often get spring weather in February only to see winter return with a vengeance. This can be disappointing for us and it also presents a challenge for actively growing early spring plants, both those introduced in our gardens and those native to the region. Two advantages to getting a head start on the year from a plant’s viewpoint, are taking advantage of available moisture in an arid land, and the dormancy of many of the creatures that might like to eat you. The downside is you may freeze or be dumped on by a fresh load of snow. Plants with much height are liable to be crushed or broken by the weight of snow or ice unless -like our conifers- they have a shape which reduces accumulation. Freezing itself is not generally a problem for winter-hardy plants, but when the ground in the root zone freezes, parts exposed to the air become vulnerable to desiccation.
There are several ways to minimize this threat. The most common is to avoid drying winds. “Stay close to the ground till it warms up!”. Many native plants, and weeds like mullein, knapweed, cinquefoil & several mustards do just that. Leaves held over from the fall are plastered to the earth in a “rosette” at spring thaw, and grow tall only when the threat of frozen ground and snow load has passed. Another strategy is to “Make your leaves thick.” Thin leaves, like thin sheets, dry fast. Our sedums and sage buttercup do this with fleshy leaves, while those of mulleins, rose campion, and sagebrush, are made thicker by a dense coat of hairs which trap a layer of still air over the leaf surface.
Another way many spring plants cope with low temperatures in spring is a bit more subtle. Nurseries sell a type of shrubby dogwood that has exceptionally bright red stems in winter. In fact, although not quite so brilliant, our native Osier Dogwoods also have red stems in winter, as do our native roses. Oregon grape often sports leaves that are a deep wine red. Many of our garden plants have deep red leaves and stems when they first emerge. Think of tulips, and peonies, and the tight red balls of rhubarb as they ready to unfurl into leaf. This red is caused by the presence of a pigment called anthocyanin and it is something of a physiological wizard. It protects plants from releasing dangerous free radicals produced by a kind of “jamming” of the photosynthetic process in cold weather. The problem is most acute on cold days with bright sunlight. If you look closely, you will notice a host of native plants, whose leaves have a telltale reddish tinge to them at this time of year. Oregon grape is especially revealing, because it’s easy to see that leaves in shaded spots remain green while those in sun, where photosynthesis is more intense, are invariably a dusky red.
My favorite tulip employs all these tactics. Tulipa humilis violacia- the “humble violet tulip?”- hails from the mountains of Kurdistan in central Asia, and is the first to bloom in my garden. The reddish shoots, bearing thick leaves and the flower bud, emerge upright from the earth. As the short stem elongates the unopened violet flower appears to wilt for several days; dropping to the ground like a devout Muslim at prayer (perhaps the origin of its species name “humilis”, for both “of the earth” and “humility”). Then, on the day the flower first opens, it dramatically stands erect to greet the sun. A small masterpiece of nature.
Dennis St. John