Tree Fertilization

If you have trees, you might need to fertilize them. Trees that grow in forests and woodlands get nutrients from their soil, but the soil in urban and suburban areas is nothing like native soils. Here's how it's different:

Soil is Compacted

Tree roots struggle to grow in compacted soil because they can’t penetrate the heavy material. Water either runs off compacted soil or collects and doesn’t drain.

It’s Really Subsoil, Not Topsoil

When developers build urban and suburban areas, they may use the subsoil from excavation as landscape soil. Unlike topsoil, this subsoil has few to no nutrients and can't support healthy tree and plant growth.

Soil is Depleted

In undisturbed forests, fallen leaves, twigs, and fruit collect on the ground. All this nutrient-rich organic matter breaks down into the soil for tree roots to use. Sadly, this is all raked up and thrown away in urban areas.

structure, fertility, and water-holding ability.

We use tree and shrub fertilizers to help trees stay healthy in urban soils. We use soil amendments for long-term soil improvement. Though they provide similar results, the two things are different.

Fertilizers

Fertilizers are fast-acting nutrient sources that may be liquid, granular, or slow-release pellets. The nutrients in these fertilizers dissolve in water, and tree roots take them up for the tree to use.

Soil Amendments

Compost and other soil conditioners contain well-decayed organic matter, such as green waste and animal manure. Adding this to your soil improves the soil's long-term

Many fertilizers are called "synthetic" because they're created or synthesized from inorganic chemical sources. This differs from an "organic" soil amendment or fertilizer made from organic matter, meaning things that were once alive (for example, leaves, wood, animal manure). Synthetic fertilizers generally work more quickly than organic fertilizers but don't have long-term benefits for soil or plant health.

When your trees lack the nutrients they need, they struggle to grow. You'll see several symptoms, including:

• Stunted growth – When a tree can’t get all the nutrients it needs, it will slow its growth to conserve energy.
• Thin or patchy foliage – A tree lacking nutrients will cut off resources to twigs and branches to conserve energy.
• Yellow leaves – Nutrient deficiency appears in a tree's leaves, making them yellow instead of healthy green.
• Dropped leaves – Your tree may drop leaves during the growing season when it doesn’t have enough nutrients and food energy to support them.
• Insects and diseases – A stressed tree has fewer natural defenses and is more susceptible to insect pest attacks.

Your tree will keep trying to grow even when it’s lacking vital nutrients, but its long-term health won’t be good. The combination of stunted growth and chronic nutrient stress during growing seasons will shorten its lifespan significantly.

Many homeowners compound the problem by mistaking the signs of nutrient deficiency for water stress and overwatering the tree. Or they over-prune, thinking this will stimulate more growth (it won't).

If you’re a homeowner buying packaged fertilizer, follow the instructions on the label. More is not better!

Signs of Overfertilization

When you give your tree too much fertilizer, you’ll see several symptoms, including:

• Brown leaf edges or leaf tips
• Yellow, limp leaves
• Leaf drop

To a homeowner, these symptoms can look just like signs of nutrient deficiency! Instead of guessing, ask a professional for help.