CHEMICAL UPDATE: Plant Growth Regulators

Plant growth regulators, or PGRs, offer a variety of benefits on top of acting as tools to reduce plant growth. Grounds care professionals are using PGRs to reduce maintenance and to improve plant vigor.


PGRs can definitely reduce mowing requirements. However, they do much more. For example:

  • PGRs suppress turf growth during overseeding to give young seedlings a quick start.

  • Some PGRs inhibit or suppress Poa annua seedheads.

  • PGRs eliminate tall seedheads in some roadside grasses (which, in some cases, might be the only reason to mow).

  • PGRs can differentially suppress growth of various turfgrass species, giving the desirable turfgrass a competitive advantage over Poa annua.

  • “Chemical edging” with PGRs controls growth of turf around tree trunks, landscape fixtures and edges, which can significantly reduce labor needed for trimming.

  • Some PGRs can improve the overall health and vigor of their turf, resulting in better color, improved stress tolerance and perhaps better root development.


Ornamental PGRs provide benefits comparable to those of turf PGRs, but also others unique to ornamentals:

  • PGRs reduce trimming needs for trees and shrubs.

  • PGRs allow grounds care professionals to eliminate messy or dangerous fruit from trees.

  • PGRs also suppress sucker and sprout growth.

  • Certain ornamental PGRs can even improve root development, branching and overall vigor.


To successfully integrate PGRs into your maintenance program, it's important to carefully balance the cost of the application with the anticipated savings in maintenance. PGRs may not always be an economical choice, but they often are.

Using PGRs to improve plant appearance or health, or improve establishment during overseeding, can be difficult to quantify in dollars and cents, and can be more of a judgment call based on agronomic and aesthetic considerations. By contrast, an application that reduces trimming (of a long hedge, to use one example) may be a clear-cut labor-saver.

The following tables are a general guide to PGRs available for turf and landscape ornamental use. Use them for preliminary planning only. They are not a substitute for label instructions, which you must read and follow whenever you use a PGR, as with any pesticide.

If you would like more information about a product, contact the supplier via the information supplied in this Update. You can also find labels via the new Pesticide Search tab on the Grounds Maintenance Web site at Powered by Greenbook, this online resource also features a list of newly registered chemical products as well as label changes for existing products. For a comprehensive list of the Chemical Update tables that accompany this article, go to our Industry Research resource at

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