Q: I am looking for a list of ground covers that grow and cover rapidly and that survive desert winters.
A: Here are a few ideas from the “Landscape Plants for the Arizona Desert” publication from AMWUA.org. All are hardy to at least 15 degrees Fahrenheit.
Fast Growth:
- Trailing acacia (Acacia redolens) — Look for the prostrate form.
- Trailing desert broom (Baccharis hybrid) — Look for non-seeding selections.
- Bush morning gory (Convolvulus cneorum).
- Saltillo primrose (Oenothera stubbei).
Moderate Growth:
- Trailing dalea (Dalea greggii) — Also try Dalea capitata.
- Trailing gazania (Gazania rigens) — look for a variety of flower and foliage colors.
- Tufted evening primrose (Oenothera caespitosa).
- Trailing rosemary (Rosmarinus officinalis) ‘Prostratus.’
- Creeping germander (Teucrium chamaedrys) “prostratum.”
- Find the entire publication online at amwua.org .
Q: Is there a good, free information source about household insect pests?
A: Yes, the University of Arizona Cooperative Extension has many publications online about various insect pests. If you can’t find a particular one, please ask me for directions. There is also an online handbook through the UA Pest Management Center at cals.arizona.edu/apmc/Handbook.html
There also are free workshops on managing pests in and around buildings. These are geared toward people who manage pests for schools and other public buildings but anyone is welcome. The next one is on Oct. 26 in Tucson. Send me an email if you want to attend or learn more about it.
Q: I need some advice on how to grow royal poinciana trees. The trees I have are babies. I have in the past lost a few I think due to over watering. I have them in different size plastic containers, in cactus, palm, and flower potting soil, in the shade with just a little morning sun.
A: The general recommendation for non-desert tree species is watering once every seven to 10 days in the summer to a depth of 24 to 36 inches. This is, of course, for trees planted in the ground. The frequency would be greater for container trees and really depends on how fast your container dries out. The time it takes for a container to dry out depends on the size of the container and how much exposure it receives. This tree likes the heat and naturally grows in a hot and humid environment. You might need to experiment with your irrigation system and your moisture meter to see how long the soil takes to dry.
The problem with growing this tree in Tucson is the cold since they cannot tolerate a freeze. Prepare for that by finding a protected place for your containers and/or getting some frost cloth to cover them.
Q: I have two mature palo verde trees in the enclosed portion of our backyard (many more in the desert). They are next to each other surrounding a rock outcropping. There was a nasty shrub in the rock outcropping that I kept trimming back, but it always returned. So I bought a small container of poison ivy killer (only shrub killer I could find) and sprayed the contents on the shrub. Good news is shrub appears dead. Bad news is one of the two palo verde trees dropped the leaves off of the branches growing from one of the three main trunks. The main branches are still green, but the small leaf bearing branches have turned brown, though still pliable. The other two main trunks of that tree and the other palo verde are unaffected. Will the tree survive and regrow its leaves?
A: It is hard to know how much herbicide your tree absorbed. The roots of mature trees extend two or three times the diameter of the crown. The best thing you can do for the trees is taking good care of them. That means deep watering once every two weeks down to about 24 to 36 inches. Make sure the water is going to the absorbing roots that are out around the drip line (the edge of the crown) of the tree. These trees need that much water anyway and flushing out the root zone may help wash out the herbicide. Time will tell if the tree got a strong enough dose to do it in.
Herbicides can be used in situations where plants are in close proximity by painting them on the offending plant rather than spraying or drenching the soil. Often this is done soon after making a basal pruning cut. This should reduce exposure to nearby desirable plants.
