Products, Vendors, CAD Files, Spec Sheets and More...
Sign up for LAWeekly newsletter
Trees are some of the most perfectly-designed organisms on the planet. They suffer from fewer nutrient deficiencies than other plants. When trees fall prey to insects or other pests, drought is a much more common factor. Some of the more severe tree diseases in North America include bark beetle (drought-induced) and hemlock wooly adelgid (non-native pest).
That doesn't mean that trees don't need phosphorus, nitrogen and minerals. They're just good at extracting these items from the ground. When planting juvenile trees, a granular time-release formula can give trees a good boost--but don't let the replanted tree dry out. If a tree starts to show yellow foliage, an iron deficiency is a possibility. Soils with extreme pH can affect the ability of plants to utilize soil nutrients. If a number of newly-planted trees start to fail, an arborist can likely spot the reason.
Finally, palm trees are another matter. Many palms and cycads have specialized nutrient requirements. When their growth stalls or shows poor color, adding water may be the worst thing you can do. Again, consult an arborist or a professional at the nursery where you purchased the product.
The text below offers some guidelines about fertilization for good tree growth, color and pest-resistance.
--Erik Skindrud, LCN editor
Unless a tree is deficient in some other element, increased nitrogen provides the most pronounced effects on the growth of the plant. But because an increase in nitrogen produces a visible increase in growth does not mean that other elements are not required. A soil test provides the best indicator of elements that may need to be added to the soil to prevent nutrient problems.
High rates of Phosphorus (P) fertilizer should not be used unless a need is indicated by a soil test. If soil test P is high then it is best to use fertilizers such as 24-0-15, 30-0-10, 32-3-10, 18-5-9, 27-3-3, or 16-4-8 with a high rate of N and a low or zero-rate of P. High rates of P can negatively affect the environment by causing excessive algae to grow in nearby lakes and streams which will, in time, kill fish and other aquatic life. Never use a fertilizer which includes any kind of herbicide around a tree. These fertilizers may be beneficial to turf, but can damage trees. From www.extension.umn.edu
Palms have exacting needs when it comes to nutrients. Research has determined the best ratios of nutrients, however. These are available in palm-specific fertilizers.
Look on the label to make sure the nutrients are in the following proportions: nitrogen (10 percent to 20 percent), phosphorous (5 percent to 10 percent), potassium (10 percent to 20 percent), magnesium (2 percent to 5 percent), and (.5 ) of manganese and iron.
The product should also contain sulfur and trace amounts of zinc and copper.
If palms are suffering from nutrient deficiencies, then supplemental amounts of the deficient nutrients will be required. Magnesium deficiencies are common on date palms (Phoenix species). Older leaves turn yellow first, progressing up to younger leaves. Leaflet tips yellow while the bases remain green. Correction of this deficiency requires the addition of magnesium sulfate to the soil.
From John Begeman, College of Agriculture and Life Sciences, University of Arizona, ag.arizona.edu
3: Pounds. Studies have shown that approximately three pounds of actual nitrogen per 1,000 square feet per year is needed to maintain the health of woody plants in most landscape situations.
6: Methods. There are six methods available to apply fertilizer into the landscape: liquid soil injection, by drill or punch bar holes in the soil, surface application, fertilizer stakes or spikes, foliar sprays, and tree trunk injection or implantation.
Francisco Uviña, University of New Mexico
Hardscape Oasis in Litchfield Park
Ash Nochian, Ph.D. Landscape Architect
November 12th, 2025
Sign up to receive Landscape Architect and Specifier News Magazine, LA Weekly and More...
Invalid Verification Code
Please enter the Verification Code below
You are now subcribed to LASN. You can also search and download CAD files and spec sheets from LADetails.