Astro 120 ME
Trinexapac-ethyl growth regulator. Slows turf growth and reduces mowing by up to 50%. Rates by grass type: Buffalo, Bent, Fescue, Ryegrass, Kikuyu, Couch.
See how much Astro 120 ME you'll need
Plant Growth Regulator Calculators
Work out exactly how much plant growth regulator you need to slow turf growth, reduce mowing frequency, improve colour and density, or manage ornamental hedge plants. Pick a product below, enter your lawn area (or number of plants for Trimmit), and the calculator does the rest.
Primo HG / Primo Maxx II
Premium trinexapac-ethyl plant growth regulator. Reduces clippings, improves density and stress tolerance. Available in 500mL (Primo HG) and 5L (Primo Maxx II).
See how much Primo HG you'll need
Trimmit
Ornamental plant growth regulator (paclobutrazol). Per-plant root drench for hedges and ground covers â Duranta, Photinia, Syzygium, Box, Viburnum, Star Jasmine, Mock Orange.
See how much Trimmit you'll need
Plant Growth Regulator FAQ
What does a plant growth regulator (PGR) actually do?
PGRs like Primo HG and Astro 120 ME contain trinexapac-ethyl, which blocks gibberellic acid production. The result: your lawn grows shorter and denser rather than taller, you mow less often, and the turf becomes more drought-tolerant and stress-resistant. Paclobutrazol-based Trimmit works similarly but is used as a root drench on hedging plants.
How often should I apply?
Trinexapac-ethyl PGRs typically last 3â6 weeks per application. Re-apply once the lawn shows signs of returning to normal growth speed. Trimmit is applied once or twice per season for hedges.
Why does the rate depend on my grass type?
Different grasses metabolise trinexapac-ethyl at different speeds. Buffalo, Couch and Hybrid Couch need lower rates (10â40 mL/100m²). Kikuyu is the most vigorous and needs higher rates (20â80 mL/100m²). Bent, Fescue and Ryegrass sit in the middle.
Will my lawn turn yellow after applying a PGR?
Some short-term colour change (slight yellowing or darkening) is normal during the regulation period â the grass is putting energy into roots rather than leaves. Colour and density typically improve after the rebound phase. Avoid applying when the lawn is under stress (drought, disease, heat).
Can I use Trimmit on lawn grass?
No â Trimmit is only registered for ornamental plants (hedges, ground covers). For lawns, use Astro 120 ME or Primo HG instead.