Growing papayas, mangos, bananas, and zapotes in Mesa, Arizona

Yesterday I went on a Sunday afternoon walk near the new Alma School Road and 8th Street fire station in Mesa, Arizona with my dad, my brother-in-law, my nephew, and two of my nieces. We stopped by at a house on 10th Street where there were papayas growing in the front yard. I rang the door bell, and the owner of the house treated us to a tour of his jungle, which included under cultivation all the following:

• papayas
• bananas
• zapotes
• persimmons

The owner told us his mango got frozen recently.

The visit got me thinking about the importance of miniclimate and microclimate. This fellow is fortunate to live on the nose of a subtle major ridge that runs east-west along 9th Place and 10th Street near Alma School Road.

Being on the ridge keeps him away from the worst of local cold air drainage. In addition, his house is near Alma School Road. That provides effective cold air drainage away from his property to the 40-foot drop down to the Salt River bottom. His papayas are growing in the front yard near the street, which provides radiant night warming in addition to cold air drainage.

Given the right property, or simply to improve an area of any property, it would be fun to design and create a microclimate for more delicate plants. A good microclimate design might include as many as feasible of the following elements.

For cold protection:

• Unobstructed cold air drainage to slightly lower land. To avoid freezing, it helps to be elevated above cold-air pockets.
• Unobstructed winter sun exposure. To keep as warm as possible, it helps if the soil is struck by the winter sun as long as possible.
• Obstructed night sky. To minimize night-time radiation heat loss, it helps to be under an awning or tree canopy. If the canopy is massive enough to act as a heat sink, it may provide additional night-time heating.
  
• Solar capture and/or reflection. To maximize winter solar capture, a reflective (white) or heat sinking (black and massive) sun wall helps.

For sun and heat protection:

• Obstructed summer sun. To avoid summertime sun and heat damage, it helps to have a shade.
• Non-reflective ground. To avoid turning your microclimate into a summertime solar oven, it helps to have a ground cover outside it that minimizes the reflection of summer sunshine into the planter.

For help designing or analyzing your canopy overhang, use a sun chart such as this one from the University of Oregon.