This is the month to begin preparing for the long-awaited fall season.  Amend the soil with compost for seasonal planting of vegetables and herbs, as well as wildflowers.  Garden centers will be re-stocking with a new supply of seed, and of course you will have a grand selection for your garden if you shop at the fall plant sale in a few weeks.

This is a good time to harvest the remainder of ripening prickly-pear cactus fruits for fresh eating or making delicious jelly.  If your prickly-pears have a late-season cochineal scale (the cottony-looking spots on the pads) infestation, wash them off with a strong spray of water.  Periodic hosing-off will keep populations low enough that they will not compromise the health of your cactus.  Very rarely is more aggressive treatment necessary.

Late in the month you may notice caterpillars munching your sacred datura (Datura wrightii) plants.  These are the larvae of the beautiful hawkmoth, which pollinates the delightfully fragrant, huge, trumpet shaped blooms that open at night through the warm season.  If you enjoy the hummingbird-like adults, don’t kill the caterpillars.  They have to devour some of the foliage to complete their life cycle.

Harvest mature seed from perennials in your garden, such as chocolate flower (Berlandiera lyrata), blackfoot-daisy (Melampodium leucanthum), desert-marigold (Baileya multiradiata), golden fleece (Thymophylla pentachaeta), four o’clocks (Mirabilis multiflora, M. longiflora, and M. jalapa), and sacred datura (Datura wrightii).  Store clean, dry seed in an airtight container in a cool, dark location.  Seed of desert-marigold and blackfoot-daisy can be planted next month.  The remainder can be put out in the spring.

Curve-billed thrashers and other critters are enjoying the remaining fruits on prickly-pear (Opuntia spp.) and barrel cactus (Ferocactus spp.).  Native desert milkweed (Asclepias subulata) will attract the attention of the monarch butterflies, as well as the queens.  The adults will sip nectar from the flowers and lay eggs.  Caterpillars will munch on buds and flowers at stem tips, but will not cause harm to the plants as they grow in size before pupating and forming chrysalids. 

Bee brush (Aloysia gratissima) shrubs are still attracting hummingbirds and painted lady, blue, and snout butterflies with their nectar.  Goldfinches and house finches are enjoying their prolific seed production.  Gregg’s mistflower (Conoclinium greggii) will attract male queen butterflies with their pinkish-lavender blooms.

Photos by Kirti Mathura

Garden Meetings:
Arizona Native Plant Society
Tuesdays, September 11, October 9, and November 13, 2007, January 8, February 12
and March 11, 2008, 7-9 p.m., Webster Auditorium

Central Arizona Cactus & Succulent Society
Sundays, September 30, October 28 and November 18, 2007, January 27 and February 24, 2008, 2 p.m., Dorrance Hall, October 28, Wildflower Pavilion, Silent Auction

Central Arizona Butterfly Association
Saturday, September 8, 1-3 p.m., Webster Auditorium

Maricopa Audubon Society
Tuesday, September 4, 7:30 p.m., Dorrance Hall