Autumn is nigh and the days are getting shorter. This tells plants to grow! Easy to do because the soil is still warm from the summer heat, but days and nights are cooler.
These factors all make September ideal for planting trees, shrubs, perennials, annuals, bulbs, groundcovers, wildflowers, herbs, vegetables … in short, everything.
Plan on getting out and doing some planting this fall. Some work now, and your yard will really bloom all winter long. It is still hot enough to break a sweat as you do all this, but if you wait until October it does not give plants quite enough time to become well-established before first frost.
Plant. Spring flowering bulbs that can take our heat. This includes amaryllis, anemone, daffodil, freesia, gladiolus, grape hyacinth, narcissus, ranunculus, and Turkish tulips (also called species tulips).
Sow. Wildflowers to sow include the ones native to this area: Arizona gold poppy (Escholtzia neomexicana), desert bluebells (Phacelia campanularia), owl's clover (Orthocarpus purpurascens), desert lupine (Lupinus succulents), Parry's penstemon (Penstemon parryi), desert marigold (Baileya multiradiata), desert zinnia (Zinnia acerosa), and golden dyssodia (Dyssodia pentachaeta). Some prairie wildflowers also do well here, including prairie coneflower (Ratibida columnaris var. lutea), Mexican hat (Ratibida columnaris), firewheels (Gallardia pulchella), blue flax (Linum lewisii) and red flax (Linum rubrum).
Divide. Separate large clumps of spring flowering perennials that have become crowded. Especially iris but also this alphabet of perennials. Any mint, including mint, horehound, monarda, pennyroyal and catnip. Blackfoot daisy, butterfly iris (Dietes vegeta), coreopsis, day lilies, fortnight lily (Dietes bicolor), garlic chives (Allium tuberosum), hesperaloe, lily of the Nile (Agapanthus orientalis), lirope (Lirope sp.), penstemon, prairie zinnia (Zinnia grandiflora), rain lily (Zephyranthes species), Shasta daisy, society garlic (Tulbaghia violacea), verbena, violet, and yarrow.
Prune. Deadhead summer-tired salvias and autumn sages for a burst of new bloom. Light pruning on anything else, just enough to shape or control rampant growth. Avoid pruning fall-flowering plants like hummingbird trumpet (Zauschneria arizonica) or the Mount Lemmon marigold (Tagetes lemmoni).
Fruit trees. Continue regular irrigation of citrus, fig and pecan trees for best production.
Remove any cracked or split fruits from citrus so energy is spent on healthy fruits.
Fertilize. Landscape plants, citrus and other fruit trees should be fertilized with a well-balanced fertilizer for good fall growth. Roses, tomatoes, peppers, and pumpkins should be fertilized with a high phosphorous fertilizer for fall flowers and fruits. Basil, herbs and lawns need a high nitrogen fertilizer for good fall leaf growth. Also treat alkaline induced iron chlorosis in roses and citrus again if the rains leeched the treatment away.
Lawn. Dethatch your Bermuda lawn for October overseeding with winter rye grass.
Herbs. Plant seeds of the cool season annual herbs like calendula, caraway, chamomile, cilantro (coriander), dill, fennel, feverfew, parsley, and salad burnet (more on these herbs later this month).
Vegetables. See my article from Aug. 19. In short, plant leafy and root vegetables including arugula, beets, bok choy, broccoli, Brussels sprouts, cabbage, carrots, cauliflower, chives, collard greens, endive, garlic, horseradish, jicama, kale, kohlrabi, leeks, lettuce (head and leaf types), mesclun mix, mizuma, mustard greens, onion, pak choy, parsnip, peas, potato, radish, raduccio, scallion, spinach, Swiss chard and turnip.
Weeds. You got rid of them all last month. Sure you did. But then our constant desert breeze, or maybe a dust devil dropped more weed seeds. The price of freedom from weeds is eternal vigilance.
Jacqueline has been gardening in the Southwest since childhood. Dr. Soule has been writing articles about how to garden successfully in our area for over two decades. Look for her column in these pages every week.