best time of year to use root killer

Determining the Optimal Time to Apply Root Killer for Maximum Effectiveness

Tree and shrub roots can wreak havoc on underground pipes and sewer systems. Using chemical root killers provides an effective solution, but timing is key for best results. This article will explore when you should apply root killer for ideal root control and drainage system protection based on climate, plant activity, and other factors.

Spring

Early spring, as soil temperatures rise above 50°F, is an optimal period to use root killer in many regions. Trees and shrubs are still dormant at this point, so the root killer can penetrate roots aggressively before new spring growth obscures pipes.

Roots also begin actively growing in spring, so are more likely to absorb the root killer chemical. And spring rainfall helps flush the product into the surrounding soil and pipe network. Regular spring application helps avoid major root intrusions during the growing season.

Mid-to-Late Summer

Summer is another prime root killer application window in warm climates where root growth remains active into late summer. Hot summer temperatures can evaporate standing water in pipes, allowing roots to penetrate seeking moisture.

Applying root killer during dry summer conditions ensures maximum exposure to actively growing root tips. Root pruning and dieback also occurs in late summer, so root killer applied then can exploit natural root deterioration.

Early Fall

Early fall just before leaf drop provides another good root killer opportunity. Soil retains summer warmth to stimulate root absorption. And plants are moving nutrients and resources into roots in preparation for winter dormancy.

Root killer applied in fall can eliminate any new root growth from summer and limit root reserves going into winter. It also protects pipes from intruding roots throughout winter when followup application is difficult in cold climates.

Avoid Winter

Avoid applying root killer during full winter dormancy in cold regions. Root growth, absorption and circulation are minimal when trees go dormant. Any root killer flushed down simply flows through without affecting roots much.

Exceptions are warmer winter climates where root activity continues year-round. Here, winter root killing may still prove beneficial. But in cold zones, it’s best to wait for early spring wake-up.

Avoid Periods of Heavy Rainfall

While some moisture carries root killers into the surrounding soil, heavy rains can simply wash the product through the system too quickly to be effective. Root killing when heavy precipitation is forecast may lead to wasted product and effort.

Wait several days after major downpours for soil to dry out before treating. Optimal periods have moderate soil moisture without saturated conditions.

Consider Tree Size and Age

Younger, faster growing trees and shrubs send out more aggressive roots with higher absorption. Their roots are also easier to penetrate and kill. Focus on vigorously growing problem trees.

Older, mature tree roots are slower growing and harder to kill. You may need repeat root killer applications or mechanical removal for large old trees. But maintaining a control regimen still limits further damage.

Repeat Application Frequency

For chronic root issues, apply root killer every 4-8 weeks during the active growing season. This frequency continually weakens and kills new root growth before it can expand into pipes. Coordinate with seasonal root flushing schedules.

For preventative treatment without current intrusion issues, apply only 2-3 times per year during optimal seasons. Monitor effectiveness with camera inspections.

Match Timing to Root Killer Product

Most chemical root killers specify an optimal treatment window on their labels. Copper sulfate products work best in early spring before heavy summer root growth. Metam sodium is more effective during summer when warmer soils stimulate root absorption.

Carefully follow manufacturer instructions for whichever commercial root control product you select for best results. Timing, technique and dosage are all keyed to the specific formulation.