When indoor plants get sick, good advice is often expensive. We’ll tell you the five most important warning signals, what’s behind them and how you can react to them.
Some red flags are a clear indication of what is missing from your plant. Sick indoor plants show certain recurring signs of damage, which can be easily treated if you only recognize them in good time. We show you the five most important warning signs regarding pest infestation and plant diseases in indoor plants.
Sick houseplants: warning signs at a glance
- Light spots and white webs indicate spider mites
- Brown or yellow leaves in the wrong location
- Swarms of mosquitoes are mostly fungus gnats
- Loose leaves can result from too much dust
- Drooping leaves and brown tips from incorrect watering
Sick indoor plants: what do light spots and white webs mean?
Warning signals: If there are light spots and/or white webs of wafer-thin filaments on the leaves of your houseplants, the common spider mite (Tetranychus urticae) is usually behind them. Spider mites suck out the plant cells so that they dry up and the plant quickly dies completely. They are very widespread in indoor plants, are particularly evident in winter, and are particularly active when the air in the heating system is dry. As a preventive measure, you can ensure higher humidity, for example by spraying the plants. Popular indoor plants such as the rubber tree (Ficus elastica), the ray aralia (Schefflera), or the room ivy (Hedera) are particularly affected.
Spider mites are one of the most common pests on indoor plants
Measures: Immediately isolate the diseased houseplants from the healthy ones. If the plants are single, manageable, you can shower them off thoroughly. After drying, the crowns are then packed in a closed, transparent foil bag for a good two weeks. The warm, humid climate ensures that the pests die off. You can treat your infected houseplants, especially larger specimens, but also with pesticides such as pest-free neem or Bayer garden spider mite-free. The use of predatory mites has proven its worth in the winter garden or greenhouse. These natural enemies of the spider mites eat the pests and their eggs and provide long-term relief.
Brown or yellow leaves on the windowsill
Warning signs: is your plant on the windowsill with brownish or yellow discolored leaves that are gradually falling off? In most cases, in such a case, the indoor plants are not sick, they are just too close to the windowpane. In winter this means that the leaves that touch the pane cool down, freeze to death, and thus die off. In summer, on the other hand, it is often sunburn that causes the leaves to fall and harm the plant.
If the leaves touch the window panes directly, it can make indoor plants sick
Measures: If only it were that easy … Find a new place for your houseplants and you will see that they will recover quickly there.
Swarms of mosquitoes around house plants
Warning signs: tiny black mosquitoes that frolic in large numbers on the potting soil or buzz around the plant. Sciarid gnats (Sciaridae) are pests that occur mainly in winter and spread in large numbers on house plants. It is not the mosquitoes themselves that are dangerous, but their larvae. These live in the ground and eat the roots – which sooner or later causes the houseplants to perish. A prevention tip: Use only high-quality potting soil for your indoor plants. Sciarid gnats are often brought into the house through the substrate.
Yellow plugs help with fungus gnats
Measures: If the plant can tolerate it, you should stop watering for a while and let the root ball dry out completely. Sciarid gnats love a moist substrate, especially if it is very humus-rich. Then, take out the diseased houseplant and remove the soil as much as possible before repotting it. A layer of sand on top of the substrate will also keep the fungus gnats away. Yellow plugs, yellow boards, or beneficial insects (SF nematodes) from specialist retailers provide a remedy in equal measure. You can also put the purple blooming butterwort (Pinguicula Vulgaris) between your houseplants. It is one of the carnivorous houseplants and significantly reduces the amount of sciarid gnat infestation indoors.
Tip: Sciarid gnats don’t stand a chance with plants that are suitable for hydroponics! They do not nestle in clay granules.
Why are indoor plants limp?
Warning signals: a specific damage pattern cannot be identified. But: the houseplant looks sickly, leaves the leaves drooping, and basically looks anything but vital. Indoor plants are very dependent on the care of their owners. It is particularly important indoors that the plants can photosynthesize. But this is only possible if you get enough light. So first check whether the houseplant is correctly positioned and then check the condition of the leaves. These symptoms usually show up when the leaves of the houseplants are covered with a layer of dust.
Regular dusting is essential for indoor plants
Measures: Clean your houseplants from dust every four to six weeks. You can simply shower off smaller plants. Make sure that you protect the root ball from too much water with a bag or something similar. Larger plants that are difficult to move or large-leaved specimens can be cleaned of dust with a damp (and soft!) Cloth or brush.
Brown tips, waterlogging, and drooping leaves
Warning signs: The houseplant is dropping its leaves. Waterlogging has formed in the pot and the roots are already rotten easily. Or the tips of the leaves are dry and brown. If one or more of these symptoms sound familiar to you, then you’ve fallen into the classic houseplant trap: you’re watering too much! It is hard to believe, but most houseplants do not die because they are not watered enough, they die because their keepers mean it well to them. Plants need different amounts of water depending on the season or phase of growth. The location also plays an important role, as houseplants that are above a heater need significantly more water than those that are in an unheated room.
You can water plants too much …
Actions: Find out about the houseplant of your choice! For example, cacti and succulents require very little water because they can store it. Always check the pots. If water has accumulated in it, it is urgent to remove it and be careful to waterless next time. Special moisture meters are also available in stores that you can stick in the ground to read when exactly you need to re-water. You can also find out about this with a so-called finger test. Rub some substrate in your hands and only pour when it is dry. A drainage layer at the bottom of the pot helps against waterlogging. You can just use some sand or gravel for this.