How Much Does Tree Fertilization and Plant Health Care Cost?

Plant health care, or PHC, is a program for keeping the trees, palms and shrubs on a property healthy before something goes wrong. It can include soil treatments, fertilization, trunk injections for specific pests or diseases, and checking on the trees between visits.

Fertilization is one piece of it, not the whole thing. Some trees need help with the soil more than they need fertilizer, and some need nothing at all. Our plant health care service page walks through how we assess a property and build a program.

Lawn fertilization is a separate service through O’Neil’s Land Care, part of the same company. See lawn fertilization for that.

Most of what we put into or around a tree is dosed by the size of the trunk. Product labels give a rate per inch of trunk diameter, and UF/IFAS describes the injection math plainly: multiply the trunk diameter by the label rate to get the dose for that tree. A bigger tree takes more product, so it costs more to treat.

We measure diameter the standard way, at about 4.5 feet off the ground. You can get close yourself by wrapping a tape measure around the trunk at chest height and dividing by 3.14.

Because the price follows the trunk, you can rough out a number before we visit. Three oaks with 15, 20 and 25 inch trunks add up to 60 inches. At our soil therapy rate of about $2.80 per inch, that comes to about $168.

These are the rates we use and where the lines landed on work we sold between January and mid October 2026. Our minimum for any visit is $95, and most properties have more than one thing worth doing on the same visit.

• Organic soil therapy for hardwoods. About $2.80 per inch of trunk diameter, added up across the trees treated. It goes into the root zone and can include organic products like compost tea and humates. Most lines ran between about $150 and $500.
• Tree injections. About $15 per inch of trunk diameter. The product goes straight into the tree, so very little is lost to drift or runoff. Most lines ran between about $180 and $450.
• Growth regulator. About $10 per inch of trunk diameter. A growth regulator is a product poured on the soil around the trunk that slows how fast the tree puts on new shoots. Most lines ran between about $180 and $365.
• Palm fertilization. Priced per palm by size and type: about $16 for a small palm, $24 for a medium, $28 for a large, and $70 for a date or royal palm.
• Tree fertilization. A flat price per visit, typically $150 to $190.
• Soil sample. $95.
• Lethal bronzing prevention. Preventive palm injections start at $95 for a single palm on a site, and fertilization is usually included at that price.

A program that covers several large oaks and a row of palms will run higher than these lines, and a few large commercial properties sit well above the typical range. The estimate lists each service on its own line so you can choose what to do first.

A soil test tells us what the trees are growing in before we decide what to add. The UF/IFAS soil testing lab reports soil pH, which is how acidic or alkaline the soil is, along with how much phosphorus, potassium, calcium and magnesium is available. It also tells you whether lime is needed.

It does not test for nitrogen. UF/IFAS explains that Florida’s warm, wet climate keeps changing nitrogen in the soil, so there is no reliable test for it.

In Pinellas, a soil test also matters for a legal reason. The county does not allow phosphorus unless a soil test shows the soil is short on it. In our program, a baseline soil sample is typically pulled at the start, and in my opinion it is worth doing before anyone buys fertilizer.

Palms have their own needs. UF/IFAS recommends a slow release palm fertilizer, 8-2-12 with 4 percent magnesium, and warns that high nitrogen lawn fertilizer near palms can cause potassium deficiency serious enough to kill them. The UF/IFAS palm fertilization guide has the details.

Lethal bronzing is a palm disease caused by a phytoplasma, a type of bacteria, carried from palm to palm by sap-feeding insects. UF/IFAS has confirmed it in Pinellas County, and it affects cabbage palms, Canary Island date palms, queen palms and others. On a palm with fruit, the first sign is usually fruit dropping early.

Once a palm shows symptoms, UF/IFAS says it cannot be saved and should come out. Healthy palms nearby can be protected. UF/IFAS recommends testing them and injecting the ones that test negative with an antibiotic called oxytetracycline every three to four months for at least two years. That repeat schedule is why the per-visit price matters on this one.

From June 1 through September 30, Pinellas County’s fertilizer ordinance does not allow nitrogen or phosphorus on lawns or landscape plants. Clearwater posts the same rule, and applications pick back up October 1.

Other parts of the ordinance apply all year. Phosphorus needs a soil test showing a shortage, granular fertilizer with nitrogen has to be at least half slow release, and fertilizer has to stay 10 feet back from ponds, wetlands and seawalls.

Summer does not stop all plant health care. Insect and disease injections are not fertilizer, and UF/IFAS describes a palm fertilizer with no nitrogen or phosphorus, 0-0-16 with 6 percent magnesium, for places with a summer ban. Anything with nitrogen or phosphorus waits until October.

PHC works best on trees that are still in decent shape. It is not the first step for a tree that is dead, in fast decline, or sitting in soil that was crushed or cut during construction. Those need the site problem fixed, or a different plan.

If a tree has gone too far, I would rather tell you than sell you a program for it. Our page on when tree removal is necessary covers how we make that call. Whether to treat or let a tree go is a decision you and your arborist make standing under the tree.

You also do not have to enroll every tree. Starting with a soil sample and the few trees that matter most to you keeps the cost down and shows you what the soil needs.