How do I fix fungus gnats on cannabis?

Small dark flies whose larvae feed on plant roots and organic matter in the growing medium. They thrive in moist conditions and can cause root damage and stunted growth. Let the top 2–3 cm of substrate dry out completely between waterings. Apply yellow sticky traps to catch adult flies. Drench the medium with a Bacillus thuringiensis israelensis (BTI) solution to kill larvae.

How do I fix botrytis cinerea (grey mold) on cannabis?

A fungal disease that causes grey, fuzzy mold on flowers, fruits, and leaves. It spreads rapidly in humid, poorly ventilated environments and can devastate entire crops. Remove all infected plant material immediately and dispose of it outside the grow area. Lower humidity and increase air circulation through the canopy. Apply an organic fungicide such as potassium bicarbonate to surrounding plants.

How do I fix powdery mildew on cannabis?

A common fungal disease recognized by white powdery spots on leaves and stems. It reduces photosynthesis and weakens the plant, thriving in warm, dry conditions with poor air circulation. Remove and destroy heavily infected leaves. Spray a milk-water solution (1:9) or potassium bicarbonate as an organic remedy. Improve airflow and reduce humidity around plants.

How do I fix aphids on cannabis?

Tiny sap-sucking insects that cluster on stems and leaf undersides. They excrete honeydew, promoting sooty mold growth, and can transmit plant viruses. Spray plants with a strong jet of water to dislodge colonies. Apply insecticidal soap or neem oil to leaf undersides. Introduce ladybugs or lacewings as biological control.

How do I fix thrips on cannabis?

Minute, elongated insects that scrape plant cells and suck out the contents, leaving silvery streaks on leaves. They can transmit viruses and are difficult to control. Apply blue sticky traps to monitor and catch adults. Spray with insecticidal soap or spinosad on leaf undersides. Release predatory mites (Amblyseius cucumeris) for biological control.

How do I fix whitefly on cannabis?

Small white flying insects that congregate on leaf undersides, sucking sap and excreting honeydew. Heavy infestations cause yellowing, wilting, and reduced plant vigor. Hang yellow sticky traps just above the canopy. Spray insecticidal soap or neem oil on leaf undersides. Release Encarsia formosa parasitic wasps as biological control.

How do I fix spider mite on cannabis?

Tiny arachnids that feed on plant cells, causing stippling and yellowing of leaves. They produce fine silk webbing and thrive in hot, dry conditions. Rinse plants with a strong water spray, focusing on leaf undersides. Apply neem oil or insecticidal soap every 3–4 days for two weeks. Release predatory mites such as Phytoseiulus persimilis.

How do I fix sulphur deficiency on cannabis?

Young leaves turn uniformly pale yellow-green while older leaves remain green. Growth slows and stems may become thin and woody. Sulphur is essential for protein synthesis. Supplement with a sulphur-containing nutrient like Epsom salt or a complete base feed. Check and adjust pH into the 5.8–6.3 range (official chart). Flush the medium if salt build-up is suspected, then re-feed with a balanced solution.

How do I fix potassium deficiency on cannabis?

Older leaves develop brown, scorched edges (leaf scorch) and may curl. Plants become weak and more susceptible to disease. Potassium is vital for water regulation and fruit quality. Supplement with a high-potassium booster during late veg and early flower. Verify pH is 5.8–6.3 (official chart). Reduce excess Ca/Mg if levels are above target.

How do I fix nitrogen deficiency on cannabis?

Older, lower leaves turn pale yellow and eventually fall off as nitrogen is mobilized to newer growth. Overall plant growth is stunted and yields are reduced. Increase the dose of a complete base nutrient with adequate nitrogen. Verify and adjust pH to optimal range. Repot or top-dress depleted soil.

How do I fix iron deficiency on cannabis?

Young leaves show interveinal chlorosis – the tissue between veins turns yellow while veins remain green. Severe cases can cause leaves to turn almost white. Bring pH back into the chart range of 5.8–6.3 to free up iron. Apply a chelated iron supplement or a balanced micro-nutrient feed. Improve drainage and root zone temperature.

How do I fix magnesium deficiency on cannabis?

Interveinal chlorosis appears on older leaves first, with yellowing between the veins while veins stay green. Leaves may develop reddish-purple tints and drop prematurely. Supplement with Epsom salt (1g/L) or a Cal-Mg product. Check and balance pH within 5.8–6.3 (official chart). Reduce excess potassium if it's the cause.

How do I fix phosphorus deficiency on cannabis?

Older leaves develop dark green to purplish discoloration, especially on the undersides. Growth is stunted, root development is poor, and flowering may be delayed. Warm the nutrient solution to 18–21 °C (official chart). Apply a P-K booster during transition and early flower. Verify pH is in optimal range.

How do I fix calcium deficiency on cannabis?

New growth is distorted and curled, with brown necrotic spots on leaf tips and edges. Roots become stunted and fruit may develop blossom end rot. Supplement with a chelated Cal-Mg product. Improve transpiration with steady airflow and moderate humidity. Check and balance the rest of the nutrient profile.

How do I fix nutrient burn (ec too high) on cannabis?

Leaf tips dry out and burn when the feed is stronger than the plant can use, often because EC climbs as the tank level drops. Bring EC back to the chart value for the plant's week. Make a fresh tank. Lower EC in hot weather.

How do I fix pale leaves under led on cannabis?

Under LED lights plants can turn pale between the veins and produce small, light flowers even on a full feed. Give 18 hours of light in veg and 12 hours in flower. Add VitaSweet at 1 ml/L from week 3 to week 8. Check pH is 5.8–6.3.

Visual Guide

What does your plant look like?.

Pick the photo that matches your problem. You'll see what's wrong, how to fix it and which Vitaponix product helps.

Pests
Fungus Gnats
Fix: Let the top 2–3 cm of substrate dry out completely between waterings.
More →
Try
VitaRoot
Mould & mildew
Botrytis Cinerea (Grey Mold)
Fix: Remove all infected plant material immediately and dispose of it outside the grow area.
More →
Try
VitaCal
Mould & mildew
Powdery Mildew
Fix: Remove and destroy heavily infected leaves.
More →
Try
VitaSilica
Pests
Aphids
Fix: Spray plants with a strong jet of water to dislodge colonies.
More →
Try
VitaSilica
Pests
Thrips
Fix: Apply blue sticky traps to monitor and catch adults.
More →
Try
VitaSilica
Pests
Whitefly
Fix: Hang yellow sticky traps just above the canopy.
More →
Try
VitaSilica
Pests
Spider Mite
Fix: Rinse plants with a strong water spray, focusing on leaf undersides.
More →
Try
VitaSilica
Deficiencies
Sulphur Deficiency
Fix: Supplement with a sulphur-containing nutrient like Epsom salt or a complete base feed.
More →
Try
VitaBase
Deficiencies
Potassium Deficiency
Fix: Supplement with a high-potassium booster during late veg and early flower.
More →
Try
VitaBulk
Deficiencies
Nitrogen Deficiency
Fix: Increase the dose of a complete base nutrient with adequate nitrogen.
More →
Try
VitaBase
Deficiencies
Iron Deficiency
Fix: Bring pH back into the chart range of 5.8–6.3 to free up iron.
More →
Try
VitaSweet
Deficiencies
Magnesium Deficiency
Fix: Supplement with Epsom salt (1g/L) or a Cal-Mg product.
More →
Try
VitaSweet
Deficiencies
Phosphorus Deficiency
Fix: Warm the nutrient solution to 18–21 °C (official chart).
More →
Try
VitaBulk
Deficiencies
Calcium Deficiency
Fix: Supplement with a chelated Cal-Mg product.
More →
Try
VitaCal
Feeding & light
Nutrient burn (EC too high)
Fix: Bring EC back to the chart value for the plant's week.
More →
Try
VitaBase
Feeding & light
Pale leaves under LED
Fix: Give 18 hours of light in veg and 12 hours in flower.
More →
Try
VitaSweet

Doses and targets come from the official Vitaponix feeding chart. Vitaponix nutrients are plant nutrition, not pesticides or fungicides. Always follow the laws on cannabis cultivation in your country.

Research sources (Wageningen University & Research — does not endorse Vitaponix)

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Open the feeding chart Shop Vitaponix →

What does your plant look like?.

Fungus Gnats

Botrytis Cinerea (Grey Mold)

Powdery Mildew

Aphids

Thrips

Whitefly

Spider Mite

Sulphur Deficiency

Potassium Deficiency

Nitrogen Deficiency

Iron Deficiency

Magnesium Deficiency

Phosphorus Deficiency

Calcium Deficiency

Nutrient burn (EC too high)

Pale leaves under LED

Get the full 10-week feeding schedule.