Pests are an inevitable part of growing plants — but a pest problem doesn't have to become a disaster. The key is early identification, starting with the gentlest effective treatment, and putting preventative measures in place so the problem doesn't return.
This guide covers the four most common plant pests we hear about from our customers: aphids, spider mites, thrips, and fungus gnats. For each one we'll show you how to identify it, how to treat it naturally first, and when to escalate to stronger solutions.
The Go Grow Pest Treatment Ladder
Before diving into individual pests, here's the approach we recommend for all pest problems:
- Identify correctly — misidentifying the pest is the most common reason treatments fail
- Remove affected material — prune heavily infested leaves and dispose of them away from the garden
- Start with preventative and organic treatments — gentler on the plant, the environment, and beneficial insects
- Escalate if needed — if organic treatments aren't controlling the infestation, move to targeted stronger treatments
- Prevent recurrence — environmental controls and regular monitoring are your best long-term defence
Pest 1: Aphids
Aphids are small, soft-bodied insects (1–3mm) that cluster on new growth, stems, and the undersides of leaves. They feed by piercing plant tissue and sucking sap, causing distorted growth, yellowing, and a sticky residue called honeydew that can lead to sooty mould.
How to identify: Look for clusters of green, black, or white insects on shoot tips and leaf undersides. Distorted or curling new leaves are a telltale sign. Ants farming aphids on stems is another indicator.
Natural treatment: A strong jet of water dislodges aphids effectively on robust plants. For persistent infestations, Spray2Grow Thrips Protection Spray also provides good coverage against soft-bodied insects including aphids. Apply to all leaf surfaces, especially undersides.
Prevention: Encourage natural predators — ladybirds, lacewings, and hoverflies all feed on aphids. Avoid over-feeding with high-nitrogen nutrients, which produces the soft, sappy growth aphids prefer.
Pest 2: Spider Mites
Spider mites are tiny arachnids (under 1mm) that are almost invisible to the naked eye but cause very visible damage. They thrive in hot, dry conditions and can devastate a plant rapidly if left unchecked.
How to identify: Fine webbing on the undersides of leaves and between stems is the clearest sign. Leaves develop a stippled, bronze or silvery appearance as mites pierce individual cells. In severe infestations, leaves yellow and drop.
Preventative spray: If spider mites are a recurring problem in your growing space, apply Spray2Grow Spider Mite Protection Spray as a preventative foliar treatment before infestations take hold. Regular application creates a hostile environment for mites to establish.
Natural treatment: Dr Schimmel Organic Spider Mite Terminator is a plant-safe, organic treatment that's highly effective against spider mites at all life stages. Apply as a thorough foliar spray, covering all leaf surfaces and undersides. Repeat every 3–5 days for two to three applications.
Stronger intervention: For serious or established infestations, Dr Schimmel SMT Spider Mite Terminator 25ml or MITECIDE Spidermite provide more powerful control. These are best reserved for when organic treatments have not achieved sufficient knockdown.
Prevention: Spider mites hate humidity. Keep relative humidity above 50% and ensure good airflow. Avoid letting growing spaces become hot and stagnant — a circulating fan makes a significant difference.
Pest 3: Thrips
Thrips are slender, fast-moving insects (1–2mm) that rasp the surface of leaves and petals to feed on plant cells. They're difficult to spot due to their size and speed, but the damage they leave is distinctive.
How to identify: Silver or bronze streaking on leaf surfaces, often with small black dots (frass). Distorted flowers and leaves. Adult thrips are pale yellow to brown and move quickly when disturbed.
Natural treatment: Spray2Grow Thrips Protection Spray is specifically formulated for thrips control and is our recommended first-line treatment. Apply as a thorough foliar spray every 5–7 days. Thrips have a fast lifecycle so consistent repeat applications are important to break the cycle.
Prevention: Thrips are attracted to stressed plants and enter growing spaces through vents and openings. Maintain plant health with consistent feeding and watering, and use fine mesh screens on ventilation openings where possible.
Pest 4: Fungus Gnats
Fungus gnats are small flies whose larvae live in the top layer of growing media, feeding on organic matter and — in larger numbers — on plant roots. Adult gnats are a nuisance but it's the larvae that cause real damage.
How to identify: Small dark flies hovering around the base of plants and growing media. Larvae are tiny white maggots visible in the top 2–3cm of compost. Affected plants may show wilting or slow growth despite adequate watering.
Natural treatment: Allow the top layer of growing media to dry out between waterings — larvae need moisture to survive. Beneficial nematodes (Steinernema feltiae) are a highly effective biological control, applied as a soil drench to target larvae directly.
Prevention: Avoid overwatering, which creates the moist surface conditions fungus gnats need to lay eggs. Top-dressing with a layer of perlite or grit creates a dry surface barrier that deters egg-laying.
General Prevention: Your Best Long-Term Defence
Regardless of which pest you're dealing with, these environmental and cultural practices significantly reduce the risk of infestation:
- Good airflow — moving air makes it harder for pests to establish and disrupts their lifecycle
- Regular monitoring — check the undersides of leaves weekly; catching problems early makes treatment far easier
- Healthy, well-fed plants — plants under stress are significantly more susceptible to pest attack
- Quarantine new plants — always isolate new plants for 1–2 weeks before introducing them to your growing space
- Clean your growing space — remove dead leaves and plant debris promptly as these harbour pests and disease
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