Most problems which occur with indoor plants are environmental (water, light, temperature etc.), and are simple to remedy. Even problems with insects can be easily resolved if you get onto it early.
Below is a list of the most common problems encountered: their symptoms, the cause and the cure.
Leaves wilting despite being well watered. Leaves may turn yellow or brown and fall off.
Cause: Over watering. Roots rot due to lack of oxygen because soil is always saturated.
Solution: Only water when top of soil is dry. Check your plant’s water requirements, it may need to dry out almost completely in between watering, most plants need less water during the cooler months.
Check drain holes are not blocked or the base of the pot is not standing in water.
Leaves wilting, eventually turning brown at the tips. Older leaves turn yellow and fall off. Soil / potting mix is dry.
Cause: Under watering.
Solution: If soil is completely dry then water twice. Water until water runs out of drainage holes, leave 10 minutes and repeat until you are confident the potting mix is thoroughly re-wetted. If potting mix has completely dried out, it can shrink away from the sides of the pot, and water can run down the sides instead of re-wetting the potting mix. If this persists, dunk the entire pot in a bucket of water for 5 minutes, then let it drain.
Sudden leaf drop – commonly in a freshly brought plant, or one that has moved location.
Cause: Shock. Usually from moving from one environment to another.
Solution: Common in the ornamental figs (Ficus). If you must move them, try to reduce all other stresses, keep water, temperature, and light at ideal levels. They recover on their own anyway, it is just a messy time with leaf drop. When watering, use a weak liquid fertiliser (quarter strength) and use tepid water.
Plants are ‘stretched’: stems seem thin and weak, long stretches of stem between leaves which tend to be small and pale in colour. Plant not located in a bright position.
Cause: Not enough light.
Solution: Move the plant to a brighter spot, or open curtains/blinds and allow more light into the room. Don’t over compensate, suddenly thrusting it into the sunshine may be its death knell. You may want to prune the plant back to encourage it to bush out once in a better location.
Leaves go crispy brown at the margins, new leaves emerge smaller in size, while old leaves curl. Plant is located in a bright position.
Cause: Too much light.
Solution: Some shade lovers need to be in a lower light position. Move to a less bright spot, or use sheer curtains to filter light.
Bleached areas on leaves.
Cause: Sun scorch – commonly due to moving plant to a sunnier location.
Solution: Plants need time to adapt to new conditions. If moving a plant outside for the summer, move to a shady spot and gradually allow it to get more sun. Many will need to stay in some shade. Similarly inside, gradually move a plant that has been in a dark position into a brighter one. This helps avoid shock (see above).
Leaf drop, sudden wilting, and general failure to thrive. You are confident there is no under or over watering and your fertilising is appropriate.
Cause: Check the plant is not in a draft, either from a heating vent or an air-conditioning duct. Could also be a ‘chilling effect’ from cooler weather.
Solution: Move to a place out of the draft, or adjust vents on outlets away from plants. Move away from cold drafts from doors or windows.
Dry looking tips of leaves, browning on leaf margins, leaf drop, and general failure to thrive. You are confident there is no under or over watering and your fertilising is appropriate.
Cause: Insufficient humidity.
Solution: Raise humidity levels by grouping plants together, sitting above water on a tray of pebbles – never in water – regular misting.
Pale spots on leaves of hairy leafed plants.
Cause: Cold water splash on leaves.
Solution: Water carefully with very narrow tipped watering can – water the potting mix only, avoid getting water on the leaves. Use tepid or room temperature water.
Spots on leaves of succulents – especially Sanseverias.
Cause: Water splash on leaves when temperatures are cool – can lead to fungal problems.
Solution: Water carefully and water potting mix only. Give succulents a spray wash only in warmer weather. If problem is severe, remove infected leaves and spray rest of the succulent with a fungicide.
The spots wont ‘heal’ and the leaf become unblemished, all you can do is prevent it occurring again and outgrow the problem.
Rapid growth, lots of leaves, but no blooms.
Cause: Too much fertiliser, incorrect N:P:K balance.
Solution: Excess Nitrogen in the fertiliser causes lots of foliage growth at the expense of flowers. Reduce fertilising, do not fertilise when dormant. Use a fertiliser low in Nitrogen when flowers are desired. This is particularly important for orchids.
Gradual failure to thrive, leaves start to go yellow and drop – older leaves do this first. Leaves become smaller and plant growth slows right down.
Cause: Not enough fertiliser.
Solution: Plants need fertiliser when they are growing. If you apply slow release fertiliser at the start of the growing season you are usually OK, but with some plants you may need to top up with applications of liquid fertiliser. If just using liquid fertiliser, then fertilise regularly during the growing season.
Drooping plants combined with leaf margins and tips browning (burning). Often accompanied by white speckles or even a white crusty build up on soil surface, visible when the potting mix is dry.
Cause: Salt build up in potting mix from fertiliser.
Solution: You need to flush salts out of the potting mix which have built up. See baag.com.au/flushing-salts-from-indoors
White (salty) crust build up on the pot – especially on terracotta pots, glazed or natural. Any part of the plant that touches this deposit ‘burns’.
Cause: Salt build up on the pot from fertiliser.
Solution: Flush salts as described in baag.com.au/flushing-salts-from-indoors. If an empty pot then renovate the pot as described in
Plant wilts rapidly, perks up after watering, but seems to wilt too quickly after watering.
Cause: Possibly pot bound. Too much root in the pot and not enough potting mix to hold the water.
Solution: Repot as described in www.baag.com.au/growing-indoor-plants-successfully
Wilting and leaf loss after repotting.
Cause: Transplant shock.
Solution: Keep in semi shaded location and give optimal care until perks up.
White waxy fluffy material on plants.
Cause: Mealy Bugs
Solution: Isolate plant to avoid spreading. Check all your nearby plants. Can use natrasoap spray or if a small infestation then using a cotton top dipped in rubbing alcohol (surgical spirit, available from chemist) and dab the mealy bugs. Repeat as necessary.
Generally oval shaped, small waxy tightly adhering insects anywhere on the plant, often in clusters, can be almost any colour.
Solution: Isolate plant to avoid spreading. Check all your nearby plants. Can use natrasoap spray or if a small infestation then using a cotton top dipped in rubbing alcohol (surgical spirit, available from chemist) and dab the scale. Repeat as necessary.
Foliage is flecked, yellow, bleached, silvery or bronzed. Profuse fine webbing often seen with heavy infestations. Very tiny pests generally on the undersides of the leaf.
Solution: Very difficult to control. Confidor now generally thought to be ineffective as it is an insecticide and mites are not insects, and the chemical pathways of control do not work on them. If a bad infestation consider throwing out the plant. If you want to keep the plant, isolate from other plants. Try spraying the mites with natrasoap. Repeat regularly until infestation is completely eradicated. Increase humidity around plant to prevent further infestation. Another method is to fill a bucket with water at 44C and immerse the entire plant including pot for 15 minutes. Keep the water at 44C. Leave to drain. A day later do a follow up spray with natrasoap. Keep a vigilant eye out and repeat as necessary. Keep plant isolated until clear of mites. Increase humidity to prevent further infestations.
If you feel like you have done everything you can for a plant, and yet it still looks sick, get rid of it, either pass it on to a friend you don’t like very much or send it to the great compost heap in the sky. Sometimes it is simply the wrong plant, just not suited to the environment you live in.