Hot Gardens Newsletter: October 2004
Cool Time to Plant. Now is the absolutely best time to start planting in the American Southwest. Our mild September weather means the earth has already begun to cool down to temperatures friendly to plant roots. The roots will grow over winter and make the plants more vigorous in Spring and better able to withstand summer heat.
Amend! Amend! Be sure to add organic amendments around your existing plants now and dig it in – being careful not to disturb established roots. Another technique – one we use – is simply to add organic amendments in a layer on the top of perennial borders with minimal digging in. The amendments will do double-duty: enriching the soil and serving as a protective mulch. For new plantings be sure to dig in the soil amendments as deeply as you can. Ask your local nursery if you should add chelated iron and sulfur to your soil before planting trees and shrubs. It is probably not a good idea to add much nitrogen fertilizer at this time of year. Nitrogen fosters leaf growth when what you want in winter is root growth.
Hot and Hotter. If you plan to remove part or all of a lawn and replace it with rock mulch, consider this: In direct summer sun the surface temperature of the rock mulch will be over 150 degrees F. and that heat will radiate back to your home. The new artificial grass, which looks amazingly real, also warms up to about 150 degrees F hot in summer sunshine. So if you are replacing grass with rocks, be sure to plant trees or shrubs densely enough to shade the rock mulch or your summer cooling costs will skyrocket! You can find lists and photos of fast growing trees and shrubs suitable for our hot, dry climate on this site.
Hopbush Maze. Among shrubs we personally prefer: the desert native Hopbush (Dodonaea viscosa) which has green or reddish leaves and an open structure. It grows fast and becomes quite large, but can be controlled by light pruning. Recently we visited a garden with 8 foot high Hopbush hedges lining paths that wound through the garden. The effect was almost like a maze, but with the openness of the Hopbush, one could see through the “maze walls” so there was not the sense of being trapped.
Some Like It Red. Along with surface temperature, another factor to consider with rock mulch is the color to choose. We all love red sandstone and the red rock mulch created from it. We have, however, seen some examples of changing grass to red sandstone mulch that leave a lot to be desired aesthetically. Red rock mulch – miles of it – recently replaced grass in the roughs of a local golf course and it looks like Christmas every day. The green is too green, the red, too red. Another golf course selected white rock mulch for their socially-responsible roughs and the glare off the white rock is almost unbearable. Perhaps the most attractive of the almost-no-water usage golf courses is the Badlands in Las Vegas. They simply left the roughs in close-to-native condition and added more light brown rock mulch and small black boulders.
Our personal preference is the champagne color mulch with some red in it. But if you just “gotta have red”, install plants with gray-green foliage in and nearby the mulch. In areas throughout the West where red sandstone predominates, Mother Nature supports gray-green plants. The colors complement each other.
Mesquites Rule. To follow up on the news in the September newsletter about Mesquites (Prosopis) in Ethiopia – yes, Australia has a severe mesquite problem. The tree, which was initially introduced in the mid-1800s for shade and cattle fodder has become an infestation in large areas of the country, with dense stands of mesquites overtaking grazing lands. The cattle that feed upon the mesquites are also the ones spreading the seeds around. The Australian government has embarked on a vigorous eradication program, using fire, chemicals and a mesquite-loving moth, but with limited success. The mesquite has also been introduced into the Caribbean, India , throughout North Africa and even in parts of China. It may turn out that Mesquites are the trees that will rule the world!
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