Question: When should pre-emergent herbicides be applied in the Phoenix area? I am trying to maintain a desert landscape, but I am surrounded by grass people! Their overseeding and overwatering combined with blown seeds have created a seasonal crop of weeds and grass that has become difficult to pull by hand. I use some glyphosate herbicide, but I would like to stop the uninvited crops from germinating.
Answer: Scottsdale Weed Control & Fertilization advised timing the grass pre-emergent applications around your neighbors' overseeding schedules.
If no rain is imminent, you need to water everything in. Ideally, you should wet the ground prior to application, then again immediately after application. This is to ensure that the pre-emergent is incorporated into the soil and not degrading on your rock top dressing.
Because of the amount of water needed to germinate grass, runoff or overspray from sprinklers can pose a problem. It can dilute the herbicide, rendering it less effective and making it difficult to achieve complete control in certain areas. Before applying any product, always read the label and follow the manufacturer's instructions. If there are any questions regarding application, call the number on the label.
Q: Does crepe myrtle grow here, or does the heat make it susceptible to disease or death?
A: They are beautiful trees, but I would advise against planting one in the Phoenix area. They grow here, but it is not the ideal situation for them. They would prefer to be in a slightly higher elevation with cooler summers. They tend to get salt burn on the leaf edges here. They also take a lot of water and prefer to be mulched regularly.
Q: I planted two eremophila hygrophana in the spring of 2010. They had been doing well and blooming. However, in the past few weeks they have bloomed little and now have stopped blooming. The leaves were turning brown and dry at the base of the plant, so I increased the watering. The leaves have stopped turning brown, but now there are no blooms. I would like information on the watering needs of the plants.
A: You should water your eremophila about twice a week during the hottest part of the summer, cutting back to once a week toward the end of September. Little to no water is needed in the winter. I'm sure your plant will begin blooming again once it recovers.
Q: Once in a while, I lose a hibiscus plant. It begins to drop its leaves, then dies. I have tried Spectracide all-purpose spray and Bayer's root insecticide and give them Ironite, but I still lose the plant. I believe something is eating the roots or boring into the stems to kill the plant. Any suggestions? They are on a drip system that comes on every day in the summer for about half an hour.
A: I doubt that there is a problem with any insects. You should be watering your hibiscus in the summer only about twice a week, but for three hours each time.
Q: Is there a cactus, plant, tree or bush in the desert you could use as a water source?
A: There are no plants, cactus or otherwise, that provide water as a drinkable liquid source. There are some plants whose fruits might provide a little bit of moisture, but not enough to slake a thirst if you are lost in the desert.
Q: I have a 10-year-old peach tree in Surprise that has never provided any fruit. It receives sufficient water and nutrients, gets pruned yearly and flowers in late winter or spring. Very small peaches (about an inch) are produced, and then they dry up. What's wrong?
A: Hopefully, your tree is planted in the full sun. Try thinning the fruit to see if that helps. About three weeks after bloom time, remove all but one fruit from each of the small branch offshoots where the fruit is produced. Leave the largest peach to survive. Sometimes frost can be the culprit. The flowers may not show signs of frost damage, but the fruit will.
Babcock is former assistant director of horticulture at the Desert Botanical Garden. E-mail your garden questions to firstname.lastname@example.org.
Valley hibiscus plants need three hours of drip watering twice a week in the summer.
View subscription options