Pima County Gardening Seasonal Reminder - May

• Prepare for the extreme heat of summer. Check your irrigation system for leaks and perform maintenance as needed. Consider a
  free “water efficiency audit” of your home and garden. If you live in the City of Tucson, look into their “Zanjero” program.
• Most vegetables and many newly planted landscape plants will need some shade when temperatures reach 95 or more. One
  solution is a 30%-40% shade cloth. Maintain 3 inches of mulch to keep roots cool, suppress weeds, and reduce moisture loss.
  Leave 3” of clearance around trunks. Use of mulch is also good fire-wise strategy.
• Citrus may drop some fruit; this is normal as the tree drops what it can’t support. They may drop old leaves to replace them
  with new ones. If you notice leaf curling, it may be a sign of drought stress.
• Spray Italian cypress, juniper and other evergreens as well as roses and pyracanthas with a strong jet of water to remove spider
  mites. Yellowing needles or leaves and fine webbing are the first signs of spider mite damage. Inspect and take action if
  necessary at least weekly (Refer to Spider Mites, Backyard Gardener below).
• Leaf-cutter bees, one of our common pollinators, may cut circles in the new leaves of tender plants such as roses and
  bougainvillea. While unsightly, it does not harm the plant and no action is necessary.
• Plan or install active or passive Water Harvesting systems to capture the rainwater before monsoon begins.
• Pull dead annual wildflowers or collect their seeds.

• Plant heat loving flowers such as moss rose, gaillardia, zinnia, Madagascar periwinkle, verbena, celosia, and salvia, as well as
  desert-adapted perennials such as autumn sage, gaura, and bulbine.
• Plant starters of basil, eggplant, and peppers into the soil. Plant seeds for cantaloupe, cucumber, peppers, watermelon, okra,
  cowpeas, asparagus beans (also called “yard-long beans,”) and summer squash. Plant sweet potatoes.
• Plant and transplant agaves, palms, and other heat-loving plants such as desert trees.
• Plant heat-loving native or desert adapted trees. Plant or transplant palms.
• Remove pups from agaves & yuccas and transplant them if desired. If planting in a location without shade, consider adding
  shade cloth until they are established.
• Plant or transplant cacti this month because the warm soil temperatures facilitate root growth. Raised, slightly mounded, and
  open locations with fast-draining soil provide good homes. Plant at the proper depth and orient in the same direction. This
  helps the plant adjust and limits the risk of sunburn. If the original orientation is unknown, protect the cactus with at least 30%
  shade cloth until new growth appears.

• For oranges, tangerines, and grapefruit, this will be the 3rd of 3 annual feedings for these varieties of citrus. Lemons are later.
  Evenly spread it under the tree, starting one foot from the trunk and continuing out several feet. Water the fertilizer into the soil
  immediately after applying. If young leaves remain yellow, apply chelated iron to the soil following label directions.
• Fertilize palms in mid-spring and early summer, ensuring thorough watering within 24 hours. Use a palm-specific fertilizer, which
  typically contains about three times more nitrogen and potassium than phosphorus (the first and third numbers on the bag are
  about three times the middle number). These fertilizers also include magnesium (Mg) and other essential micronutrients
  tailored for palms.
• Fertilize roses every 3-4 weeks.
• Fertilization is not necessary for native cacti but will benefit flowering hybrid cacti such as trichocereus species. If used, apply an
  all-purpose fertilizer at no more than half-strength.

• May is one of the hottest and driest months of the year, often with hot, dry winds. Plants need more frequent irrigation to keep
  them healthy.
• Vegetable and flower gardens may require daily watering.
• Non-desert trees and shrubs will need a good soaking every 7-10 days. Use a soil probe to assure water is getting down to a 24”
  depth for shrubs and 36” for trees.
• Desert-adapted trees and shrubs may require a soaking irrigation once this month to prevent drought stress. Water slowly to
  reduce runoff and you need to reach the same depths as above.
• Cacti generally do not require irrigation, but during a particularly dry summer they will benefit from some irrigation – but no
  more than every two weeks.
• Bermudagrass should be irrigated to a maximum depth of 6” every three days.

City of Tucson Zanjero Program, free water audits

Ten Steps to a Successful Vegetable Garden

Drip Irrigation basics

Planting and staking trees

Diagnosing Home Citrus Problems

Oranges for Southern Arizona

Diagnosing Rose Problems

Landscape management practices for passive water harvesting

Harvesting rainwater

Flower Planting Guide for the Low Desert

Propagating Agave and Cacti from Seeds

Problems and Pests of Agave, Aloe, Cactus and Yucca

Cactus, Agave, Yucca, and Ocotillo

How to Transplant a Cactus

Arizona Landscape Palms

Efficient landscape watering

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.