Guide
Authors
Laurie Vance
Paul Larson
Deborah North
Publication Date: January 2025 |
View PDF
September in the garden is a special time. This month marks the end of monsoon season. The intense heat and humidity of summer is mostly past, and the mercury is beginning to fall, especially overnight. Now is a good time to clean up any monsoon damage from storms or wind and prepare your beds for new plants. Look forward to starting your fall vegetable crops as the temperatures begin to wane toward month's end. And do not forget to sit back and enjoy a cool evening breeze now and again while enjoying the fruits of your labor.
Maintenance
- Take the opportunity to clean up any monsoon damage.
- Discard split citrus and pomegranate fruit. Damaged fruit will attract fruit flies and other insects.
- Help plants recover from summer heat by pruning off dead and dried branches.
- Lightly prune roses and remove old or dead canes in mid-September. Remove spent blooms. Pick up and discard all cuttings as they can harbor insects and diseases.
- Deadhead spent blooms and prune back leggy plants.
- Pull weeds before they set seed.
- In garden beds, mix in a starter fertilizer containing both nitrogen and phosphorus before planting. Read Ten Steps to a Successful Vegetable Garden to learn more.
- As the sun begins to shift, relocate container plants to sunnier locations.
- Hose off susceptible plants that are dusty to control spider mites. Spider Mites has more information.
- If you notice something that looks like bird droppings on citrus trees, it could be the orange dog caterpillar which matures into the giant swallowtail butterfly. These will not cause major damage to a mature plant, but you may wish to pick them off a younger plant.
- Divide iris beds every 3 to 4 years as outlined in the article Bearded Iris.
Planting
- Plant flowering bulbs such as amaryllis, narcissus, iris, rain lilies, and ranunculus. Choose a location with morning sun. Keep soil damp but not wet. Use mulch to hold in moisture. Read Bulb Planting to learn more.
- Vegetables and non-native annuals require enriched soil. Check out the articles in the more information section for specific plants.
- Sow seeds indoors for cilantro, chives, parsley, sage, thyme, and oregano. Winter herbs prefer sunshine and monthly feedings once transplanted into the garden.
- Sow seeds for carrots, radishes, spinach, lettuces, turnips, green onions, beets, chard directly into the garden by mid-month.
- Sow seeds or plant transplants of sweet peas, French marigold, snapdragon, lobelia and dianthus.
- Sow seeds of broccoli, cabbage, cauliflower, brussels sprouts in trays to be transplanted next month.
- Plant strawberry plants where they will receive protection from afternoon sun.
- Plant deciduous fruit trees that do well in the desert, such as figs and pomegranates. Read Growing Common Figs in the Low Desert to learn more.
- If you prefer not to plant any fall veggies, consider planting cover crops like hairy vetch, annual rye, peas or clover which will help maintain your soil's porosity and even potentially fix nitrogen into depleted soil. The article Cover Crops has more information.
Fertilizing
- September is the time to do the 3rd citrus feeding of lemons and limes, if you did not already do so in August. Refer to the Citrus Fertilization Chart for Arizona to learn more
- Feed stone-fruit trees such as apricots, peaches, and plums in elevations over 3500’. These nutrients will be stored in the tree roots for use in the spring. For lower elevations, hold off on until spring.
- If you have roses, return to full-strength slow-release fertilizer this month.
- Fertilize beds of greens and herbs using a balanced fertilizer before planting.
Watering
- Adjust irrigation frequency based on the rains, maintain your summer schedule until temperatures drop.
- Continue to keep an eye on pomegranate and citrus trees for fruit splitting. This could be an indication of too much water for the former and/or sun-damaged rinds that cannot expand for the latter. It is important for these trees to have a consistent watering schedule.
- Monsoon rains are subsiding and now is a good time to consider adding passive and/or active rainwater harvesting.