Do Drought Tolerant Trees Still Require Fertilization?

Droughts are common in much of the United States, including Southern California. And while droughts are devastating to many common plants and trees, others can thrive with relatively little water. These species are considered drought-resistant, and they include species such as:

  • California Sycamore: While growing up to 100 feet in height, these giant trees are very drought tolerant and require surprisingly little water. Despite this, they are very attractive and are a nice source of shade during the warmest months of the year.
  • Australian Willow: The Australian willow can grow to stand thirty feet tall, and its beautiful drooping olive leaves give it a classic willow look.
  • Jacaranda: The Jacaranda can grow to fifty feet. And while their towering stature provides shade, it’s their beautiful blossoms, which range from pale lavender to deep purple or blue, which makes them very desirable.
  • Flowering Pear: The flowering pear tree also grows up to fifty feet, and this drought-tolerant tree is marked by its beautiful white flowers in the spring and summer that turn fiery red during the fall.

These trees are just a few of the drought-tolerant varieties that thrive in the San Diego area – even when it becomes more arid than usual. Other common varieties include the Brazilian Pepper, Camphor, Chilean Mesquite, Crape Myrtle, and Desert Willow, among others.

And while many drought-tolerant trees can beautify your landscape and provide cooling shade for your home and property, a common question that arises is whether they need fertilizer or not. The rationale is that since many drought-tolerant trees do not need any water during a dry spell, they may also not need fertilization.

Indeed, most mature trees and shrubs do not require any fertilizer to thrive when favorable soil conditions are present. It’s crucial to remember that plants produce their food through photosynthesis, meaning that they will only need sunlight and water if the soil has the required minerals and nutrients. And drought-tolerant trees only require a very small amount of water to complete photosynthesis.

Unfortunately, soil conditions are not always optimal. Signs that the soil is deficient in nutrients include poor growth of the tree, poorly colored leaves, small leaves, early dropping of the leaves, and little annual growth.  To complicate matters, nutrient-deficient soil is not always the culprit. Other factors that could cause the same signs include insect infestation, adverse weather conditions, and diseases that affect trees.

The best way to know whether or not fertilizer will help your tree thrive is by having the soil tested. A soil test will tell you the pH of the tree, which indicates whether the soil is acidic or alkaline. Arid climates often result in alkaline soil. When the soil is alkaline, plants fail to absorb nutrients as well as they would in neutral conditions. The pH scale ranges from 1 to 14, with a reading of 7 indicating neutral conditions. Rainwater is slightly acidic, while most tap water in the US tends to be alkaline. Most plants prefer a ph between 5.5 and 7, although many drought-resistant varieties can thrive in environments with an alkaline pH with the proper care.

Regions prone to droughts often have soil that is high in salts, featuring little organic material, which contributes to the alkalinity of the soil. Fertilizer can be used to offset the soil and water alkalinity. The most commonly applied nutrients are nitrogen, phosphorus, and potassium. Those that contain calcium, magnesium, and sulfur are also sometimes used. Fertilizers can also contain nutrients such as zinc or iron in small quantities.

If you do find that your soil needs fertilizer to help your drought-tolerant trees thrive, there are many options to consider. You can choose from options that include: fast-release vs. water-soluble, organic vs. chemical, and slow-or controlled-release fertilizers. Selecting the right fertilizers depends upon the unique conditions of the tree and its soil. It’s crucial to select one that contains the right minerals to balance the conditions and allow your tree to get what it is lacking.

And after you have selected the right fertilizer, you will also want to consider the proper amount of fertilizer, the optimal time to apply it, and application methods. The process for helping your tree thrive can become complex quickly, and selecting the wrong fertilizer risks making the situation worse. While drought-tolerant trees generally require less maintenance and care than other types, it will fail to thrive if the soil is not providing nutrients. To learn more about how to optimize conditions for your drought-resistant trees in the San Diego area, contact Tree Barber today.