Grass Grub & Porina Management
Protecting pastures with natural soil support
Grass grubs and porina can significantly reduce pasture growth, weaken plants, and limit nutrient uptake. Many growers are seeing excellent results using our products, with fewer grubs and improved pasture health.
This isn’t because the products directly kill pests — rather, they support natural predators in the soil, improve pasture resilience, and help plants recover faster from feeding damage.
Why grass grub and porina damage occurs
Weakened pastures: Stressed or nutrient-poor pastures are more vulnerable to pest feeding.
Low soil biology: Poor microbial activity reduces natural predator populations and slows pasture recovery.
Nutrient inefficiency: Nutrients are less available, limiting regrowth after grub or porina damage.
By strengthening the whole system, pastures become less hospitable to pests and more able to recover if damage occurs.
Where our products fit (practical tools growers use)
Our products help pastures resist and recover from pest pressure:
Lazerhume
Enhances soil biology, supporting natural predator populations and nutrient cycling.
Restore
Adds extra biological support to stressed pastures, helping plants recover quickly.
Turbo N
Supports nitrogen efficiency, promoting rapid regrowth after pest feeding.
Optimise iO
Supports microbial activity and nutrient availability, improving overall pasture resilience.
Using these products consistently helps pastures recover faster, reduces pest impact, and strengthens long-term soil health.
Best Timing for Grass Grub Management (NZ)
Primary Window: Late Summer → Early Autumn
(February – April)
This is the most effective and commercially relevant timing.
Why this window works best:
Grass grub eggs have hatched
Larvae are small, actively feeding, and near the surface
Soil temperatures are still warm → biology is active
Pastures can still respond and recover before winter
What this achieves:
Reduces the impact of larvae while they’re most vulnerable
Strengthens root systems before winter stress
Improves pasture recovery and limits patch expansion
Spring (September – October)
Spring applications are about recovery, not prevention.
Larvae are larger and feeding deeper
Damage may already be severe
Soil biology is only just waking up
When this approach won’t help
Extremely high pest infestations may still require monitoring or targeted intervention.
Poor pasture condition or very low soil fertility may limit recovery.
Even in these cases, our products improve soil function, plant growth, and natural predator activity, supporting longer-term pest management.
Related growing problems
Pest damage often occurs alongside:
Supporting soil health and pasture resilience helps reduce visible damage and improve productivity.
Frequently asked questions
Do these products kill grass grubs or porina directly?
No — they support soil biology and natural predators, which in turn reduces pest populations.
How quickly will pastures recover?
Visible improvements can appear within weeks, depending on pasture type, soil condition, and pest pressure.
Can these products replace chemical control?
They complement other management strategies and can reduce reliance on chemicals, but severe infestations may still require targeted intervention.
Key takeaway
By supporting soil biology, nutrient cycling, and natural predator activity, pastures become stronger, recover faster, and experience less pest pressure. Using our products is a natural, effective way to manage grass grub and porina while improving overall pasture health.
Explore all common growing problems and solutions in our “Growing Problems Hub.”