Plant Care – preventative treatments against common houseplant pests

Note: These are my opinions and experiences, I am no expert and I have not been paid or incentivised to share my thoughts and reviews of any sellers, products or people mentioned in this post.

Plant parenthood is not all lovely and fun. I learned this the hard way.

I did not even think indoor plants would get pests. To be fair the only plant pests I knew about were outdoor pests such as Aphid’s that eat roses (spoiler; they can also come indoors!) and slugs! I am yet to see slugs in the house.

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Damaged Alocasia leaf – I actually think this was caused by incorrect watering rather than pests but noticing these changes made me check and treat for pests.

But there are some that definitely live on indoor plants if you are unlucky enough to get an outbreak. The main ones that attacked my plants are:

1. spider mites
2. fungus gnats
3. mealy bugs
4. thrips

But you can also get others, such as scale and indeed aphids.

I am mentioning the ones I have personally experienced below, but I have to stress that preventative plant care is the best weapon against these. To do so I use a combination of neem oil and horticultural soap.

I used to use stronger insecticides, especially when infestations got really bad but since I use the neem oil and soap mix, I have not had a really bad outbreak of anything. *touch wood*.

My plant care routine to prevent pests involves the following steps:

1. 2-3 times a week I check my plants’ leaves. The under side and top of the leaves. I check for any changes in damage, brown spots, yellow discolouration, curling of leaves.
2. Every 7-10 days I dust the big leaves of my monstera and other bigger plants. Some plants get a shower to clean the leaves which is kinda fun.
3. Keep high humidity – pests such as spider mites hate this – so I spray plants 1-2 times a day but now it is winter I keep water containers on the radiator and also plates filled with pebbles and water under my prayer plants.
4. Every 7-10 days I spray my plants with a neem oil and horticultural soap mix. I use the ones from pink sun and they work for me. The solution I make is for 1 litre of water. I add 5ml neem oil and 10ml soap. I then thoroughly spray the top and underneath of the plants and any nooks and crannies something could be hiding in. (New plants get treated every 3-5 days for 2 weeks)
5. If in any doubt – isolate the plant and treat it. I have not found any issues with using the natural components such as neem oil and horticultural soap. I have found that chemical insecticides can damage young leaves but if things get bad you may need something stronger.

Since adopting those steps I have stayed on top of any bad outbreaks. Previously the plants that have been worst affected for me were pepperoni happy bean, pepperoni hope (this one died), and calatheas have had mild problems with spider mites and thrips in my house.

A thing I have not tried is using predatory mites or things that eat the pests in the house. I loved watching ladybirds eat aphids in the summer in our garden but have not tried these measures in the home. Have you?

Below some more rough details on the pests I have encountered and more references if you want to do more reading.

Spider mites

Spider mites are the first type of house plant pest that really made itself known in my house. I found them to especially love calatheas and as I started to purchase a few varieties I noticed how some had small bits of webbing on them. I have a fear of spiders, so I was of course convinced that this was webbing caused by tiny spiders. I was almost right. On closer inspection the webbing is not as structural as a real spider’s web and a bit weirdly sticky and generally accompanied by lots of brown dots on your plant. This is because the spider mite bites into the plant and this causes the brown dots and the sticky webbing being left behind.

To treat agains them, you can initially try to wash them off with a strong stream of water. I use my shower head, but do be careful to check the water temperature and pressure so you don’t damage your plant leaves. I also would make sure you have well draining soil and let the water run off, if you can’t avoid getting the soil wet.

Spider mites hate water and humidity, so if you keep your environment humid you have chance of discouraging them. I also cut off any badly infested leaves and dispose of it. Beware that they travel by wind so isolate your infested plant. A mix of neem oil and horticultural soap also helps deter these pests.

Also something I learned today – dust actually encourages them! So dust your plants. Maybe with a damp cloth so you are upping the humidity at the same time.

Pests like to hide underneath leaves but also in these areas where new leaves emerge.

Fungus Gnats

OMG. I had a bad case of fungus gnats in my house. This was 100% caused by me over watering in my plants. In the end I need up repotting 40 plants. Since then I have mostly kept them at bay.

Apart from being annoying they don’t tend to really hurt the plant but the babies live in the plant soil and may eat old roots.

For preventative measures I have read that they hate neem oil, so when I treat my plants with neem oil I spray a couple of pumps onto the soil of the plants too, just in case there are any hiding. But generally get rid of them I’ll use the sticky tape you can buy and let the top of the soil dry out. The larvae live in moist soil at the top of the pot so if you can let it dry out and bottom water for a month or forever that should help.

Mealy bugs

These bugs also suck the life out of plants. They tend to look like small cotton wool balls on your plant which is odd. Sometimes they are mistaken for fungus. A bad infestation can cause damage to leaves. These will turn yellow and curl and die.

To treat against mealy bugs, you can first hose off the plant and then use rubbing alcohol and a Q-tip to remove any stubborn ones and rub off any sticky mouldy looking substance. If the infestation is less bad you can isolate your plant and treat it with a neem oil mixture every other day to disrupt the lifecycle of the bugs and it also acts as a repellent.

Thrips

I actually think I confused these massively with spidermites initially. These look like tiny white or black bits on your plant. Almost like pepper. You tend to find them on the top of leaves and they cause similar damage as the other pests. Dots of damage appear on the leaves and eventually the leaves curl ip as the life is sucked out of it.

For treatment you may need a combo of neem oil and horticultural soap and if you have a lot of adult thrips, those sticky tapes that work for fungus gnats may be useful too to stop them spreading.

References

• How to identify common houseplant pests
• About houseplant pests
• Houseplant pests
• Common houseplant pests
• Uses and Benefits of Neem oil