The Plant Problem Solver

ThePlant Problem Solver

Quick Fixes & Garden Hygiene

Before you reach for the heavy-duty chemicals, you likely have the solution in your cupboard.     

These are effective "home remedies" for a range of fungal and pest issues.

• Milk 
• Baking Soda 
• Hydrogen Peroxide 
• Isopropyl Alcohol
• Meths
• Dish Soap 
• Vinegar
• Coarse sand

Hygiene Hint: Always wipe your snips and secateurs with Isopropyl Alcohol or Meths between plants.   It’s the best way to stop diseases from hitching a ride around your garden.

The Gold Rule: Always test a home spray on one leaf first and wait 24 hours. Avoid spraying in the heat of the midday sun to prevent "frying" the foliage.

1. White "dust" on leaves (Powdery Mildew)

• The Look: Leaves look like they’ve been dusted with flour or icing sugar.
• Home Remedy: Mix 1 part milk to 9 parts water. Spray on a sunny day.
• Advanced DIY: Mix 1 Tbsp Baking Soda + 1 tsp dish soap in 4L of water.
• The Pro Fix: Use a Sulphur-based spray or Copper Fungicide.

Top Tip: Improve airflow and avoid watering the leaves directly.

2. Black "Dust" or Filthy Leaves (Sooty Mould)

• The Look: A black, charcoal-like film covering the leaves that can be rubbed off with your finger.
• The Cause: This is a fungus that grows on "honeydew"—the sticky waste left behind by sap-sucking insects like Aphids, Scale, or Whitefly.
• The Fix: You have to get rid of the bugs first!   Wash the leaves with warm, Soapy Water to loosen the mould, then treat the plant with Neem Oil or Horticultural Oil to kill the insects responsible.   
• The "Big Guns": For severe or stubborn infestations, you may need to reach for a Systemic Insecticide.  This is absorbed by the plant and kills the bugs from the inside out when they try to feed.

3. Sticky Leaves or Tiny Bugs (Mealy Bugs, Aphids & Scale)

• The Look: Tacky residue or clusters of tiny green, brown, or white bugs on new growth.
• Home Remedy: Use a Hydrogen Peroxide mix (1 part peroxide to 3 parts water) to kill pests on contact.
• Advanced DIY: For stubborn Scale or Mealybugs, dip a cotton bud in Meths or Isopropyl Alcohol and dab them directly.

4. Brown, Crispy Leaf Edges

• The Look: Brittle brown tips or edges, often on indoor plants.
• The Cause: Usually low humidity (heat pumps!), dry drafts, or inconsistent watering.
• The Fix: Move away from heaters and keep watering consistent. 
• Use a Seaweed tonic (Seasol) to help the plant recover from the stress.

5. Chewed Leaves or Tiny Holes (Caterpillars & Slugs)

• The Look: Missing chunks or "shot holes" in the foliage.
• The Remedy: Go on a night-time mission with a torch.
• The Pro Fix: Use Derris Dust for caterpillars or Pet-friendly Snail Pellets to protect your seedlings.

6. Yellowing Leaves

• The Look: Pale leaves, often starting at the bottom of the plant.
• The Cause: Usually "wet feet" (overwatering) or the plant is just hungry for nitrogen.

The Fix: Let the soil dry out.  If it’s still yellow, apply a Slow-release fertiliser or a pinch of Epsom Salts to get the green colour back.

7. White Crust or Pale Spots (Water Spots)

• The Look: Chalky white circles or "streaks" on the leaves that look like dried salt.
• The Cause: Usually "Hard Water" (mineral buildup from tap water) or dried residue from a previous nursery spray.
• The Home Remedy: Mix a little Vinegar or Lemon Juice (about a teaspoon) into a litre of water and wipe the leaves with a soft cloth. The acidity dissolves the minerals.
• Top Tip: For indoor plants, use rainwater or distilled water to stop the spots from coming back.

8. Tiny Yellow Speckles & Fine Webs (Spider Mites)

• The Look: Leaves look "dusty" or washed out with thousands of tiny pale dots.  If you look closely at the stems, you’ll see very fine, silk-like webbing. 
• The Cause: Spider Mites.  They thrive in hot, dry, still air (especially indoors or under eaves).
• Home Remedy: They hate moisture!   Give the plant a thorough "shower" in the sink or with a firm hose spray to knock them off and disrupt their breeding.
• The Pro Fix: Use Neem Oil or a specific Mite Killer. Increase the humidity by misting the plant or moving it away from dry heat sources.

9. Rust Spots

• The Look: Bright orange, yellow, or brown powdery pustules on the underside of leaves.
• The Cause: A fungal disease called "Rust" that thrives in damp, still air.
• The Home Remedy: Remove and bag any affected leaves immediately. Avoid overhead watering.
• The Pro Fix: Copper Fungicide is the best bet here to stop the spores from spreading to the rest of the garden.

10. "Leggy" or Pale New Growth

• The Look: New stems are long, thin, and much paler than the rest of the plant.
• The Cause: Low light. The plant is using all its energy to "reach" for the sun.
• The Fix: Move it to a brighter spot.  If you can't move it, give it a "haircut" (prune it back) to encourage it to grow thicker and stronger from the base.

 

11. Brown Scorched Spots (The "Magnifying Glass" Effect)

• The Look: Distinct brown, dried-out patches on the leaves, often circular or following the shape of a water droplet.
• The Cause: Watering in the middle of a hot, sunny day.  The water droplets sit on the leaves and act like tiny magnifying glasses, focusing the sun's rays and "cooking" the leaf tissue underneath.
• The Fix: Unfortunately, you can’t "un-burn" a leaf.  You can snip off the worst ones for aesthetics, but the best cure is prevention.
• Top Tip: Always water in the early morning or late evening.  If you have to water during the day, keep the hose at the base of the plant and keep the foliage dry!

 

12. Tiny Black Flies (Fungus Gnats)

• The Look: Tiny black flies (resembling fruit flies) hovering around the soil or scurrying across the surface of the pot.
• The Cause: Overly damp potting mix.  The flies are attracted to the moisture and decaying organic matter to lay their eggs.
• The Home Remedy: Let the soil dry out!  The larvae can't survive in dry soil.  You can also place a dish of Apple Cider Vinegar with a drop of dish soap nearby to trap the adults.
• The "Sand Trick": Put a 1–2cm layer of coarse sand or decorative gravel over the top of the soil.  This stops the adults from reaching the damp soil to lay eggs and prevents the babies from crawling out.
• The Pro Fix: Use Yellow Sticky Traps to catch the flyers, and for the larvae in the soil, use a Hydrogen Peroxide drench (1 part peroxide to 4 parts water) when you next water.   It fizzles away the larvae on contact without hurting the roots.