It’s not always bad to see a spider or two hanging out in your hydroponic garden. But if that “spider” is actually a spider mite, you’ve got trouble. Unlike helpful spiders that may snack on pests, spider mites are there to set up an all-you-can-eat buffet on your plants.
Use this guide to spot spider mites early, get rid of them fast, and keep them out of your hydroponic system for good.
Quick Guide: Beating Spider Mites (2-Minute Plan)
- Inspect leaves—especially the undersides—for mites, eggs, speckling, or webbing.
- Prune or remove the worst leaves/plant to stop the spread.
- Spray mild cases with soapy water or neem oil.
- Escalate heavy infestations with Azamax (per label).
- Optional: introduce predatory insects (ladybugs or predatory mites).
- Prevent: quarantine new plants, use a grow tent, keep temps/canopy dust down.
🌱 Pro Tip: Use your phone’s macro mode to zoom the leaf undersides—mites and eggs are tiny.
What Are Spider Mites?
Despite the name, spider mites aren’t spiders. They’re tiny arachnids—related to spiders, ticks, and scorpions—that weave fine webbing across leaves and stems. Adults are about 1 mm long and can look yellow, green, or red depending on species and life stage. They prefer the undersides of leaves and reproduce fast: eggs can hatch in about 3 days, and new adults can start laying eggs in around a week.
How Spider Mites Damage Hydroponic Plants
- Stippling/speckling: tiny pale dots as mites pierce cells and suck out fluids.
- Webbing: fine silk threads across leaves, stems, and sometimes the fruit.
- Yellowing & curl: leaves weaken, curl, drop; growth and yield stall.
- Disease susceptibility: stressed plants are easier for pathogens to exploit.
How to Get Rid of Spider Mites in Hydroponics
1) Prune or Remove Infested Plant Parts
For light, localized infestations, prune affected leaves and dispose of them outside your grow area. If one plant is covered, removing the whole plant can save the rest of the garden.
2) Soapy Water Spray (Mild Cases)
Mix a small amount of mild, unscented dish soap in water and spray thoroughly, focusing on leaf undersides. Soap disrupts the mites’ outer coating.
- Repeat every 2–3 days for 1–2 weeks to catch newly hatched mites.
- Rinse with plain water after treatments if residue builds up.
3) Neem Oil (Organic Life-Cycle Disruptor)
I would recommend getting neem oil spray, which helps interrupt feeding and reproduction. It’s safe to use on edible crops so it won’t hurt you or your plants. Apply in the evening or with lights dimmed to avoid leaf burn, and repeat as directed.
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4) Azamax (Heavier Infestations)
If the infestation is bad you can take things up a notch with Azamax, which contains azadirachtin (from the neem tree) in a refined, consistent form. It’s effective as a foliar spray and often used in rotation with neem oil to reduce resistance. It’s made by the trusted hydroponics brand General Hydroponics and safe to use on edible crops, just make sure to follow the instructions.
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5) Predatory Insects
Predatory mites (e.g., Phytoseiulus persimilis) and ladybugs can knock down populations naturally. This method shines in tents/greenhouses; indoors, and lets face it, it’s pretty cool. You’ll just have to clean up the ladybugs as they expire.
Rotation Works: Alternate control methods (soap → neem → Azamax) and repeat on schedule to catch different life stages and minimize resistance.
Prevention: Keep Mites Out for Good
- Quarantine & inspect new plants for webbing, speckling, or eggs before they join your system.
- Start from seed or clean clones when possible to avoid hitchhikers.
- Use a grow tent to create a physical barrier against indoor pests.
- Dial the environment: mites love it warm, dry, and dusty. Keep temps in the upper 60s–low 70s°F, maintain modest humidity, and gently rinse dusty foliage.
- Scout routinely: a 30-second underside-of-leaf check during top-offs can save entire crops.
Related Guides
- Hydroponic Cleaning & Hygiene
- 10 Common Problems in Hydroponics (and How to Fix Them)
- 5 Essential Hydroponic Tools for Beginners
Spider Mites in Hydroponics — FAQs
How do I know it’s spider mites and not something else?
Look for fine webbing, speckled leaves, and tiny moving dots on the undersides of leaves. A phone macro photo makes them easier to confirm.
Will neem oil kill spider mites?
Neem oil helps disrupt feeding and reproduction. It’s most effective with repeat applications and when combined with pruning and good sanitation.
Is Azamax safe for edible plants?
Azamax is commonly used on edibles, but always follow the product label for crop listings, dilution rates, and any pre-harvest intervals.
Do spider mites live in the nutrient water?
They prefer foliage and stems, not water. Focus treatment on leaves—especially undersides—and keep your canopy clean and dust-free.
Can I eat produce that had webbing on it?
Rinse thoroughly under running water. If damage is severe or leaves/fruit look compromised, discard. When in doubt, don’t eat it.
What predators work best against spider mites?
Lady bugs are great mite hunters. They work best with good environmental control and minimal pesticide overlap.
Final Thoughts
Spider mites are sneaky, fast-breeding pests—but they’re beatable. Check often, act fast, rotate treatments, and tighten up prevention habits. Your plants (and yields) will thank you.
