Deep root fertilization in Greeley, CO

Why urban trees run short

A tree in a forest recycles its own leaf litter. A tree in a Greeley front lawn has its leaves raked and bagged every autumn, competes with turf that has been fed for grass rather than trees, and sits in soil that has been compacted by construction and foot traffic.

On top of that, Weld County soils run alkaline — often pH 7.5 to 8.2 — which chemically locks up iron, manganese and zinc. The nutrients are physically present in the soil; the tree simply cannot take them up.

That is why spreading granular fertiliser on the lawn does very little for a tree. It feeds the turf, most of it never gets past the top few inches, and it does not address the pH problem at all.

What deep root injection does

A probe injects liquid fertiliser under pressure into the root zone, typically eight to twelve inches down, on a grid pattern out under the canopy toward the drip line. Three things happen:

• Nutrients land in the zone where feeder roots actually are, rather than in the turf layer
• The injection itself fractures compacted soil slightly, which improves air and water movement
• Formulations can be adjusted for pH and chelated micronutrients, so iron and manganese stay available in alkaline conditions

Which trees benefit

Not all of them, and we would rather say so than sell a programme nobody needs.

Worth doing: trees showing iron chlorosis, newly planted trees establishing in poor soil, trees recovering from construction damage or root loss, trees under drought or pest stress, and mature specimens in heavily compacted sites.

Not worth doing: a healthy, vigorous, well-established tree putting on normal annual growth. Feeding a tree that is not short of anything achieves nothing.

Timing

Spring as growth begins, and autumn after leaf drop but before the ground freezes, are both good. Autumn is often better here — roots stay active well after the canopy shuts down, and nutrients are in place for spring.

Avoid feeding a drought-stressed tree in midsummer. Water it first. Fertiliser on a tree that cannot take up water makes things worse, not better.

Questions we get about this

Why not just use lawn fertiliser?

It is formulated for turf, most of it stays in the top few inches where grass roots are, and it does nothing about the alkaline pH that locks up iron in Greeley soils. Tree feeder roots are deeper and further out than people assume.

How often should trees be fed?

Trees that need it generally benefit from annual or biennial treatment. Healthy, vigorous trees do not need feeding at all, and we will tell you when that is the case.

Will this fix my yellow leaves?

If the cause is iron chlorosis from alkaline soil, chelated iron delivered to the root zone helps, though it is usually ongoing management rather than a one-time cure. If the cause is root damage or planting depth, feeding will not fix it.

Is it safe around pets and kids?

The material is injected below the surface rather than broadcast, so there is nothing left on the lawn. We will still tell you what was applied and any re-entry interval.

When is the best time?

Spring at the start of growth, or autumn after leaf drop before the ground freezes. Autumn often works better here because roots stay active after the canopy shuts down.