Tree Fertilization

Tree Fertilization And Deep Root Feeding

Managing your San Jose landscape can be a challenge. Native plants and trees do well in this Mediterranean-type climate–hot, dry, summers, and temperate winters–but non-native species need special care to thrive in an environment that sees fewer than 20 inches of annual rainfall. When you know how to feed and care for your trees in this specific climate, you’ll be rewarded with a healthy lawn and happy trees.

How Trees Grow

Like any plant, a tree establishes a root system to draw in nutrients and anchor the tree in the soil. That root system extends well beyond the tree’s dripline–the area covered by the tree canopy. Research for the UC Agricultural Libraries at Berkeley and Davis found that in some trees, the roots grow out four to seven times the radius of the canopy. Good, aerated, nutritious soil lets the roots grow deeper, while trees planted in poor soil develop a shallow root system that does not allow the tree the deep anchor it needs to sustain storms.


High-quality soil is essential to tree growth and health. The ground in San Jose is primarily clay, although some areas are sandy and a few others are loamy or sandy. Clay soil is an advantage in the Santa Clara/San Jose area–it holds water and other nutrients really well, so it doesn’t need as much fertilizer as sandy or loamy soil. The bulk of clay also helps trees stay anchored in the ground and more stable.

Clay’s best feature is that if you work fertilizers into it on a regular basis, it becomes a rich soil that is easy to work with and grows healthy, thriving plants. On its own, clay soil is so compacted that it doesn’t absorb water, leaving rainwater sitting on the ground instead of soaking on or draining off. Organic amendments and fertilizing are crucial components for proper drainage of clay.

Types of Fertilizer

Manicured lawns are the enemy of healthy soil. The leaves, twigs, and earthworms that we so diligently remove from the base leave trees without much in the way of nutrition–it’s like you’ve cleared their plates of proteins and left them with empty carbs. Fertilizers restore the ecobalance of trees, while letting you keep the grass that surrounds them. Grass competes with trees for food, and are better at grabbing the shallow nutrients than a deep-rooted tree. There are three basic kinds of fertilizer; an ISA certified arborist can test your soil to determine the right compounds for your trees.

  • Organic fertilizers come from plant and animal sources–chicken litter, bone meal, cow manure, and mushrooms. They slowly release nutrients into the soil, where they decompose as million of microorganisms feast on them. There are no harmful by-products of organic fertilizer, but they can be quite aromatic.
  • Inorganic fertilizers are chemicals–primarily sodium nitrate, ammonium nitrate, and ammonium sulfate–and are the most common tree fertilizers. A soil test is recommended before you start fertilizing with a nitrogen-heavy product as too much nitrogen is harmful. Inorganic fertilizers don’t change coil structure, they simply add the chemicals.
  • Organic Amendments are basically mulch–natural products that provide the microorganisms and composting needed to improve soil structure. Pine bark, household compost, peat moss, stable manure, and leaf mold are all good soil amendments.

Deep Root Feeding

Trees do need regular checkups by an ISA arborist to ensure they are healthy–stable, strong, and able to ward off pests and disease. If your trees are showing signs of stress, a deep-root feeding is the best way to start bringing them back to good health. West Valley Arborists use the most effective fertilizers for your soil type and trees. We draw a grid around the tree, and using a pressurized sort of syringe, inject the liquid compound 8-12 inches deep into the soil around the tree–from about a foot from the trunk to the dripline.

Deep-root feeding should be a part of your tree maintenance that includes surface fertilization, regular trimming and pruning, and removal of trees when necessary. West Valley Arborists can also assist you with the permitting for the removal of heritage trees.

Tree Service Estimate

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Great company to work with. Simon communicated well and arrived on time to provide an estimate to trim back several trees in our front yard. His crew showed up promptly as scheduled, and the project was completed, clean and professional.

Jordan Z.
Santa Clara, CA

West Valley Arborist did wonderful job on our oak tree. It looks amazing and we get complements eryday. They were very professional and took their time to do best work. We would definitely use them again in future. They did all the trimming of the huge tree, clean up and deep roots watering.

Barbara S.
Los Altos, CA

West Valley is great. I heard great things about them from San Jose. Thought they would be much more expensive. But their quote was less then most of the other companies. And they did a great job. Communication was great and they finished the job on time

Liam G.
Livermore, CA

West Valley Arborists

Our teams serve the Greater Bay Area and will gladly travel to San Jose, Los Gatos, Sunnyvale, Pleasanton, Livermore and many additional nearby cities

CALL US (408) 866-1148 or (925) 350-6878