When is growth regulator application most effective?

Applying growth regulators in early spring, when the sod has just begun to green, is most effective because this is when the grass is actively growing but not yet under the stress that can accompany the hotter temperatures of summer. At this stage, the plant is more receptive to the effects of growth regulators, which can inhibit excessive vertical growth and promote a more compact and robust turf.

Additionally, early spring applications align with the peak period of physiological activity in cool-season grasses, allowing for better absorption and efficacy of the growth regulator. The grass's growth response is typically more uniform at this time, leading to better control over growth patterns as the turf establishes itself for the growing season.

In contrast, applying growth regulators later in the season or after the grass has been mowed multiple times can result in reduced effectiveness, as the plant's growth dynamics may have changed, making it less responsive to the treatment. Factors such as increased stress from heat or drought, as well as the plant's natural growth cycles, can also negatively impact the responsiveness of the grass to the regulator.