Now that we’ve completed the critical step of “planting our water” in our growing area, it’s time to plant the overstory trees.
Phoenix has a great program through its two utility companies, SRP and APS, whereby you can get 2-3 desert adapted trees to plant in your solar arc. The programs stipulate that you need to plant the trees within 15 feet of the east, west or south side of structures. This allows the trees to provide beneficial shade on those hot sides of the house.
Two of the trees in our swale are within 15 feet of the south side of Susie and Morris’ house. The third is not. When we discussed our plan with the utility company, they were ok with us using a third tree somewhat farther away as it will cast a cooling shadow on Donna’s western façade in the summer when the low setting sun is in the northwest and on Suzie and Morris’ house in the winter when the low setting sun is in the southwest.
First we placed the trees in the swale so that their canopies will just touch at maturity. These are a thornless, hybrid Palo Verdes ( Hybrid Cercidium “Desert Museum”). Their mature height is 25-30 ft. with a 25-30 ft. wide canopy. The length of the swale is 80 feet long. We wanted some overhang on the sidewalk in front to shade passers-by so we placed that tree first and adjusted the others accordingly, making sure the other two trees were not too close to Suzie and Morris’s carport piers.
Because the trees will need to mature for a few years with their lower branches still attached to avoid “spindling” the trunks, we made sure we planted the trees where these branches would cause the least interference with the cars in the driveway. We will have to do some judicious pruning to train these trees in their formative years without damaging them – they grow really quickly, so we will keep an eye out for any problem branches. These trees with their bright green trunks and branches and dazzlingly yellow springtime flowers are going to look amazing here as they start to reach their full height.
Even better is that these trees hold up incredibly well to our superheated urban desert landscape. We can’t afford to waste time and energy growing poorly adapted trees in a site like this that faces not only the hot setting sun but is also surrounded by hardscape, increasing the heat island around it. And they thrive on only minimal waterings even during the hot summers, once they are past the first two years of their establishment phase.
After the trees were planted, my dad and Donna installed a wire trellis against Suzie and Morris’ carport. This trellis will support Hardenbergia vines to help shade the carport and block the line of site from this area into Donna’s bathroom shower window. Materials used were three metal t-stakes, three sheets of 3.5 x 7 ft concrete reinforcement wire, a handful of plastic zip ties to attach the wire to the t-stakes and a few large staples to hold the top of the wire against the flashing of the carport.
The whole thing went up in a matter of minutes thanks to a homemade water tool that drilled the holes needed for the t-stakes with water pressure.
The “water tool” consists of a 4 ft. length of bent pipe with a pressure nozzle at one end and a control valve at the other with a hose connection. Works great for drilling holes and trenches into compacted soils. It is also VERY messy! Mud everywhere!
We wanted to make sure we knew where the edge of the French drain was so we didn’t dig into it! So Donna and my dad dropped a stringline along the length of it, giving us a good visual of where NOT to dig.
All during the construction and planting of this swale, neighbors turned up to help. Some helped remove excess soil, others to level the bottom of the swale in preparation for planting. The neighbor across the street gifted my dad with some beers he sells – dad was delighted, he’ll always work for beer! And today, Doris, Donna’s neighbor to the south, lent a hand at hole digging. In the process, she also learned which species we were planting so she could try them in her yard as she was telling us she has had poor luck with many plants she’d tried on this super-heated western exposure.
And neighbors keep coming by to talk, ask questions and get inspired. My hope is that more of these projects will start popping up around the neighborhood – wouldn’t that be something to see! Maybe we could even have an impact on the flooding in this part of the neighborhood.
We planted the understory shrubs and herbaceous layers so that the plants will be touching but not crowding each other out at their mature size. Right now it doesn’t look like there’s a lot there – mostly because we purchased small, 1 gallon sized plants – they tend to withstand transplanting better in our climate and they’re way cheaper to buy.
All that’s left is to do is:
Shape and tamp the berm a few more times so it’s more compacted. We had to take down the berm by about 75% because it was too big and left us with no planting room.
Put down a layer of woodchips to help keep the soil cool and moist. This should happen next week after the tree trimmers visit. They’ll chip the tree waste and leave it for us to use.
We may install an automatic drip irrigation system to this area to use during the establishment phase and after that for monthly waterings during the driest (Spring) and hottest (Summer) months. Right now Donna will deep water this area by hand by letting a hose dribble on sections for an hour or so once a week for one more week, then twice a month, then once a month to build up moisture in that area.
And we still have left over dirt and urbanite. Donna will put out the word to the neighborhood on our Nextdoor page – that should get rid of most of it!