Hot Gardens Newsletter — Autumn 2007
The Best Tree. Chitalpa x tashkentenis trees cast a dappled shade which allows other plants to thrive beneath them. At maturity, a Chitalpa tree will be 25 to 30 feet tall. Developed from North American trees in Tashkent in the old Soviet Union, it arrived in America decades ago and has definitely proven to be one of the best trees for desert climates.
Yellow Leaves. As your garden comes to life again this Fall, you may notice that some of your plants have yellowing leaves with green veins. This may not be “Fall Color”. Your plants may be suffering from chlorosis. It is a result of a deficiency of iron or other trace minerals in the soil. To get technical about it, the iron and other minerals may actually be in the soil, but because of alkalinity they are chemically locked away and unavailable to plant roots. The short term solution to this is to add chelated iron to the ground around the affected plants. Chelated iron is available at your local nursery. The longer term solution is to add a lot of organic material to the soil to balance its pH. The addition of sulfur will also improve the soil and combat chlorosis. Chlorosis may also occur in water-logged soils as well as dry desert soils.
More About Roses. We recently saw a sizable front yard that had been converted from water-slurping lawn to desert rock mulch. Overall, it was done nicely. But the homeowners made the mistake of planting a dense row of roses along the walkway. Roses, while they grow and bloom beautifully in hot climates, do not belong in a true xeriscape garden where they receive only infrequent irrigation. They simply need too much water.
Big Rocks, Little Rocks. Many homeowners are choosing single size rock mulch for their flower beds or lawn replacement. You can achieve a much more natural effect by adding some larger size rocks to your desert landscape. By larger size we do not necessarily mean big, expensive boulders. Rocks up to the size of your fist will help create the natural look when combined with smaller rock mulch. This is very attractive if your landscape area includes a berm, a mounded area. On the berm, place a few larger rocks near the base of the mound to give the impression that these rocks rolled downhill.
Hot Nights. Rock mulch can reach temperatures of 150 degrees F. (65 degrees C.) in direct sunlight. At the end of the day the rock releases all that heat back into the air around your home, increasing demands on your air conditioning. We strongly advise homeowners to plant shrubs and trees in the rock mulch to shade it and keep temperatures down.
Local Drought Conditions. Our friends in Australia are enduring a hideous drought that has begun to have an impact on their food supply by damaging crops and curtailing ranching. So far in the U. S. we have not experienced this extreme condition nationwide. To find out how severe the drought conditions are in your local area, however, go to U.S. Drought Monitor.
Enduring Natives. Even in drought conditions, native plants tend to survive longer. The Theodore Payne Foundation just north of Burbank, California specializes in native plants and seeds as well as offering classes.
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