Fertilization
Feeding a tree's roots directly with nutrients, usually injected into the soil, to support growth and help it recover from stress.
What it is
Most urban and suburban soil is compacted, low in organic matter, or missing nutrients a tree would get naturally in a forest. Deep root fertilization delivers fertilizer straight to the root zone, usually through holes drilled or probed into the soil, rather than spreading it on the surface where grass and other plants use most of it first.
It's a maintenance and recovery tool, not a fix for a structural problem. A tree that's declining because of storm damage, poor pruning, root damage from nearby construction, or disease needs that underlying issue addressed too, not just fertilizer.
Signs you might need it
- Thin, pale, or undersized leaves, or leaves dropping early in the season
- Slow growth or dieback in the outer canopy
- A tree recently transplanted, or recovering from construction damage nearby
- Soil that's compacted, sandy, or was disturbed during landscaping or construction
- A high-value or mature tree you want to keep healthy long-term
Good to know
Not the same as pest and disease treatment, which targets a specific insect or pathogen rather than general nutrient deficiency. A soil test can confirm what a tree actually needs before fertilizing; some arborists include one, others go by visual diagnosis.
Typical cost in Ontario
Before HST. Can run up to $1,000 for larger trees or more complex root systems.
What pushes the price up or down
- Tree size and root system extent
- Soil condition and how compacted or degraded it is
- Whether a soil test is included
- Number of trees treated in the same visit
- How often treatment is recommended — usually once or twice a year for high-value or stressed trees
Ways to spend less
- Ask whether a soil test is included, or get one first, so you're not paying to fertilize for a deficiency the tree doesn't actually have
- Book several trees on the property in the same visit to reduce the per-tree cost
- A newly planted or recently stressed tree usually benefits more than an already-healthy, established one
Only one Ontario company publishes a specific price; most direct customers to a quote. A US price guide puts it somewhat lower ($100–$350), suggesting real prices vary by provider. Prices are typical ranges gathered from published Ontario price guides and company price pages in September 2026, before 13% HST. They’re a guide, not a quote: your price depends on your tree and your property. Get two or three written quotes, and check whether your city charges a permit fee.
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Related specializations
Sources for the prices on this page
- Tree Deep Root Fertilization Toronto | Al Miley & Associates (Toronto, ON)
- Deep Root Fertilizing for Tree Health - Beautiful Trees (Ontario — frequency guidance, no price published)
- How Much Does an Arborist Cost? – HomeAdvisor (US prices, in US dollars)