Question: How do I determine the idea place for trees and plants?
Answer: The Arizona Landscape Contractors Association offers a few considerations to discuss with your landscape professional before planting.
- Mature size — is there enough space for the plant to grow, both in width and height without having to excessively prune to keep it small and compact? The Arizona Municipal Water Users Association lists mature sizes for many of our low-water-use plants. Rosie suggests thinking ahead and asking yourself what the plant will look like in 10 to 15 years. Will the plant have outgrown its landscaping purpose and function?
- Growth habit — does it grow tall and upright or have a sprawling growth characteristic? Will you be forced to shear one side to get it to ‘fit’ into the space? Just because it appears upright when you buy it doesn’t mean it will continue to grow in this manner.
- Environmental factors — can influence the ultimate size of a plant. Ample watering of desert plants promotes excess growth of a shrub, causing it to ‘outgrow’ the size it would likely reach if it was watered more conservatively.
Exposure may also cause a plant to grow abnormally: a sun-loving plant growing in the shade may reach toward the sun, affecting its size and shape. This often creates a lopsided shrub if planted too close to a structure or wall.
- Varieties & cultivars — there are now several plant varieties (naturally occurring plant variations) and cultivars (nursery-bred or hybridized) with unique characteristics. Make sure when buying plants you know the cultivar’s growth habit and ultimate size.
Q: Can irrigation crack a house’s foundation?
A: Bob Brown, Arizona Foundation Solutions, a Rosie-Certified Partner, explains there is no set rule on how far away from the house a flower bed or tree should be, but it is important to keep the potential impact in mind when designing landscaping.
Landscaping, irrigation, and drainage play a significant role in the overall performance of your home’s foundation. Trees and other plants pull moisture from the soil under the foundations, which can cause settlement. Irrigated grass is typically overwatered and can potentially induce heaving. You can waterproof a foundation and line flower beds to minimize the potential impact.
Protect your home’s foundation with some landscape changes, including:
- Installing drought-tolerant desert landscaping.
- Making sure existing irrigation lines do not leak.
- Relocating plants and trees that require regular watering away from the home’s foundation.
Q: Do you have suggestions for landscaping around a pool?
A: Avoid placing plants and trees that drop a lot of leaves unless you want to spend more time skimming the pool instead of relaxing in it.
Excessive debris can clog up the filtering system and require costly repairs. However, Mark Ragel, board member of the Pool & Hot Tub Alliance Southern Arizona Chapter, encourages his clients to pick the plants they want. “Leaves from four houses away will find their way into the pool,” he says. “Modern skimmers and in-floor cleaning systems with leaf debris removal systems mitigate any leaf issue.”
Pool water contains chlorine or bromine, both harmful to plants. You’ll see the results — leaves turning yellow or brown (the whole leaf or just around the edges) and extensive leaf drop.
“In a conventional pool, one to four ppm of chlorine will not hurt any plants near a pool,” says Ragel. “Once the pool water hits the soil, the chlorine is rapidly dissipated, and plant damage will not occur.”
Even if your pool uses a salt system instead of a traditional chlorine system, plants can still be at risk for harm. Salt can harm plants in two ways.
Excessive soil salts can be left after water splashes. Leaves, stems, and roots can dehydrate when soil salts become so high that the roots can no longer draw in water. Even if the plants are watered, they can wilt from an inability to absorb the water.
When too many salts are absorbed by the roots they may reach toxic levels and kill the plant. Sonoran native plants are, in general, tolerant of moderate levels of salt in the soil. But most non-native varieties are not. Even small amounts of salt can damage them.
Ragel suggests using a root barrier because the roots could invade the pool plaster or plumbing.
Q: We bought a house on a septic system. Can we plant anything above the tank?
A: Yes, with caution. Do not plant anything edible on or near the septic field.
Planting perennial flowers grass over and near your septic system is fine. Though plants, shrubs, and trees with deep root systems can grow into the pipes and through the seams of the tank. Just one measly root can cause never-ending trouble and major repairs.
“If you know where your lines and tank is, avoid planting ANY trees near them,” cautions John Jay Harper, master gardener and regular guest on our Outdoor Living Hour. “The root zone of most trees is at least as wide as they are in spread and in most cases about 50% wider. Small shrubs are usually okay, but large bushes like oleander can pose a problem. If in doubt, don’t plant it.”
