Hot Gardens Newsletter - yellow leaf plant and chlorosis

Hot Gardens Newsletter: November-December

Too Hot To Bloom. During a recent trip to a local nursery we saw some new shrubs that may solve the hot weather shut-down problem. Every year, after the daily temperature reaches 90F or higher, plants in hot, dry climates stop flowering and stop growing. They just hunker down with their roots in the ground, trying to survive.

But now that it has cooled down, it is not too late to do your Fall planting, especially if you live in a lower altitude. Remember, Mother Nature plants in Fall and so should you. There are, however, some new yellow-leafed shrubs and perennials to liven up that all-green summer-survival garden. (Note: yellow leaves with green veins can also be a symptom of Chlorosis in plants. This nutrient condition should be treated.)

Yellow Fever. One of our favorite new shrubs is the Golden Smoke Tree, (Cotinus coggygria ‘Golden Spirit’). Like its cousin, the Purple Smoke Tree, it is an urn-shaped shrub that can grow taller than 6 feet. It can also be trained as a standard, a small tree. It prefers well-drained soil and when the leaves are exposed to full sun they become yellow and translucent.

If you are very daring you could plant several of these side by side to create a golden yellow hedge — and amaze your neighbors! Another use would be as a dramatic solo shrub sited against a backdrop of a basic green hedge of Japanese privet (Ligustrum japonicum) or Photinia. It will need regular watering during the first year, but after that it is a low water usage plant. A bonus: small, light pink flowers in summer.

Yellow Bird of Paradise (Caesalpinia gelliesii) is a variation on a desert plant that is so sturdy that the California Highway Department has installed it along freeways where it gets terrible treatment and thrives beautifully. It grows to 6 feet tall, has fine, almost lacy leaves, and large yellow blossoms all over it in summer. Depending upon your climate, it may lose those leaves in winter — or not. Regular watering for the first year, then low water usage. A bonus: do not fertilize it. The Bird of Paradise fixes nitrogen in the soil.

Forward, Mulch! There is a very good, scientific reason why you should mulch your flower beds and around your trees once or twice a year. What happens over time is that the organic mulch you dig into or spread over your flower beds gets used up — the nutrients are utilized by the plants. After the nutrient content is exhausted, the soil begins to “go backwards”, reverting to the basic native soil that existed in your garden before you improved it.

Most probably that native soil is very alkaline, hard as a rock, even saline — not what you want for a beautiful garden. By making regular applications of organic mulch you are keeping your garden soil in the condition plants need. Non-organic rock mulch, obviously, does nothing to improve the soil; it only shields plants’ roots from the heat and keeps down weeds.