Pima County Gardening Seasonal Reminder - September

• 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.
• As the sun begins to shift, relocate container plants to sunnier locations.
• Hose off susceptible plants that are dusty to control spider mites.
• 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.

• 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.
• Vegetables and non-native annuals require enriched soil.
• 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.
• 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.

• September is the time to do the 3rd citrus feeding of lemons and limes, if you did not already do so in August.
• 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.

• 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.

Irrigating Citrus Trees

Backyard Fruit Production at Elevations 3500 to 6000 Feet

Ten Steps to a Successful Vegetable Garden

Diagnosing Home Citrus Problems

Planting and staking trees

Training and pruning fruit trees

Citrus Fertilization chart for Arizona

Fall Bulb Planting Time

Bearded Iris, Backyard Gardener

Giant Swallowtail

Extension Monsoon page

For more information on any of these topics, search our database of Extension publications going back more than 100 years housed in the University of Arizona Campus Repository.