Kidnocker: September has its gardening duties, too

In parts of the country from which many of us originate, September is briskly cool mornings, pots of chrysanthemums on the front porch, “woolly bear” caterpillars frantically crossing the highway, and the beginning of colorful leaves floating to the ground.

In the desert, the approach of autumn has a different beat.

Rain chances decrease, there are fewer 100-degree days, and we see big bright-colored grasshoppers, noisy metallic-green flying fruit insects, and huge black cactus beetles. All are trying to eat their way through our gardens!

Now is the time to cut back geraniums by one-third to one-half. This will stimulate growth of new shoots and encourage better winter flowering. In the cold country, we would be thinking about throwing them away. Here we can trim them back and get ready for beautiful winter blooms.

Roses really do not like our hot summers and may be looking a bit shaggy about now. Continue removing any spent flowers and prune very lightly. Cut out dead or damaged canes and shoots that are growing from the rootstock. Do not prune healthy canes now, as they will soon begin to grow and produce strong fall bloom. Add full-strength fertilizer and then water plants deeply.

Continue watering annuals and perennials regularly. A light application of water-soluble, high-nitrogen fertilizer will encourage new growth of heat-stressed plants. Ammonium sulfate (21-0-0) is a cost-effective option.

Annual summer weeds such as spurge and pigweed can be killed by spraying with a broadleaf-weed herbicide, or by simply pulling out or cutting off the above-ground portion. Annual weeds will not grow back from roots as perennials do, but be sure to eradicate before they set seed.

It is time to consider a “garden for the kitchen.” When daytime temperatures consistently remain below 100-degrees, start sowing seeds of lettuce, beets, carrots, Swiss chard, radishes, kohlrabi, leeks, peas, and turnips. Onion sets and transplants of broccoli, cabbage, cauliflower, chives, and Brussels sprouts can also be planted when they become available in garden centers.

Cilantro, parsley, sage, thyme and oregano can be set out now. These winter herbs will need a lot of sunshine and monthly fertilizing with a complete, water-soluble plant food.

Around Labor Day is the traditional time to apply the last fertilizer application of the year to citrus. Pull and discard any split fruit that may appear this month. The rind thickens and as the fruit expands in autumn, it breaks the skin. This splitting and cracking often occurs when sun-damaged rinds cannot expand as the fruit grows. It can also be caused by irregular watering during the summer.

“Orange dog” caterpillars begin to hatch in September from eggs of the beautiful swallowtail butterflies. Often found on citrus, this caterpillar resembles bird droppings on the leaves, and can weaken young trees. Handpicking is the most expeditious way to get rid of them; however, remember that each caterpillar killed is one fewer swallowtail butterfly to be enjoyed next year.

Buy spring-blooming bulbs now while selection is best, put them into a paper bag and store in the crisper section of the refrigerator (away from the fruit). It is a surprise to many that spring-blooming bulbs will survive and flower in the desert. In October when the soil has cooled, plant in either the ground or containers. For best results, try crocus, allium, hyacinths, freesia, narcissus, and zephyranthes.

Most desert trees establish best when planted in the fall. Any tree that is not frost-tender may be planted this month. This is also a good time to remove unwanted suckers, or shape a young tree. However, do not give trees a hard pruning this month. If palms are looking yellow, they may need an application of chelated iron. This is the final recommended fertilization of the year for palms.

The beginning of cool-season planting is a perfect time to learn more about gardening in the desert. Sept. 10 is the beginning of the Green Valley Gardeners’ autumn seminars held each Thursday, 9:30 to 10:30 a.m. at East Center.

These free and open-to-the-public sessions have a different subject each week presented by authors, horticulturists, and other experts in their field. For a complete schedule, check the club Web site www.greenvalleygardeners.com.

Mary Kidnocker is a Master Gardener who writes frequently about the subject from a local perspective. Her columns are featured each Sunday.