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Scale on houseplants is a very annoying, persistent pest that everyone has to deal with if you’ve been growing houseplants long enough. In this post, I’m going to share with you how I manage scale in a simple step-by-step approach. With persistence, you CAN eliminate scale but you’ll need to have the right approach!
So keep reading, and I’ll walk you through exactly how to do it.
First of all, I wanted to briefly talk about what scale is and what it can look like on your houseplants. In this post, I show you how I treated scale on two different orchids (Phalaenopsis and Ludisia discolor), but the process is the same regardless what plant you have.
What is Scale?
Scale is an annoying pest, and unlike many pests, you won’t actually see them moving around on your plant. They’ll normally appear as brownish, oval bumps on your plant. There are soft scales, but also other species that have a harder shell.
Here is an example of a scale on one of my Phalaneopsis orchids. You can also see a shiny area on the leaf. That is not water. It’s actually a very sticky substance called honeydew that scales deposit on the leaves after they feed on your plant.
So how can you get rid of scale?
Killing Scale on Houseplants
Here is my 5 step process that I have successfully used to eliminate scale on houseplants.
Step 1: Inspect Your Plant and Physically Remove Visible Scale
This is the tedious part, but it is important. You’ll want to physically remove any visible scale on your houseplant first. This is important especially if you have the species of scale that has a hard outer shell as your spray treatment will not be effective to penetrate it.
Even if your treatment is effective, no spray will dissolve or remove hard scale, and it will appear the same even if it’s dead. So you’ll need to remove it so that you can then monitor your plant to see if you see any new scale appears.
If you have any really badly infected areas of your plant, it is probably best to prune your plant and throw those parts away. If infestation is horrible enough, it may be wise to just throw out the entire plant.
Be sure to check the undersides of the leaves, the leaf petioles, stems, flower stalks, etc. Scale can and will attack many parts of your plant. I simply use my fingernail to scrape off any hard scale. I found quite a few scales on the undersides of leaves and even on the flower stalks of my orchids!
I also like to use a toothpick to get into areas that are too small for my hand. It will make your life a lot easier and it is important to remove all the ones that you see.
I had to use toothpicks as a tool for my Jewel Orchid (Ludisia discolor) below.
In the photo above, you can see scale on the surface of the leaf, the stem, and also in the leaf axils. They will make their way in ALL the nooks and crannies! Use a toothpick for those areas to make it easier to dislodge the scale.
Step 2: Rinse Off Your Plant
Next, I like to take my plants to the shower. You can also use a bathtub, sink, or wash tub in your laundry room. Or if it’s warm enough outside, even better!
Give your plants a very thorough rinse with warm water. Don’t use cold water otherwise you can shock your plant. I use the spray attachment on my shower head to rinse the entire plant, including the underside of the leaves. It is important to be thorough.
This will help clean your plant up, remove any sticky honeydew from your leaves, and wash away the scales that are developing that are too small for our naked eyes to see.
Baby scales are called crawlers and they will move around until they find a spot to settle down on your plant. Rinsing off your plant will help to wash away a good portion of those, but you still have to continue to treat your plant, which takes us to…
Step 3: Treat Your Plant
After I let the plant drip dry a bit, I proceed with my treatment. I’ve always used insecticidal soap.
There are many insecticidal soaps available on the market and most are probably equally good. I like to use the Bonide Insecticidal Soap that you can easily purchase on Amazon. You can use it to treat other pests too including spider mites, mealy bugs, aphids, and more.
Spray all surfaces of the plant, and not just where you saw the scale. Spray for completely coverage and to the point where it is dripping.
You will not harm your plants by doing this. If you are concerning about your plant, you can always spray a small portion and monitor for any damage. I’ve never had any issues at all with a variety of plants.
Spray the surface of all the leaves, the undersides…everywhere! It is important to do this because there are scales present that haven’t developed large enough for us to see them.
Like I mentioned above, spray treatments will be most effective when the scale are in their crawler stage like I mentioned above.
Insecticidal soap has been very effective for me. I know many people use Neem Oil for pests but I’m not entirely sure how effective it really is. I personally can’t stand the smell of Neem Oil. You can also use a good horticultural oil as well.
Whatever you do, be sure to follow the directions on the label for safe usage.
Lastly, and this is optional, but I like to add a systemic insecticide as well to the soil. I didn’t do this with my Phalaenopsis since they are growing in bark, but I applied it to the soil of my Jewel Orchid. Follow the instructions for application and safe use. Add it to the soil, and water it in. I like to use the Bonide Houseplant Systemic Insecticide which you can purchase on Amazon, or any nursery or hardware store.
Systemics work by the plant absorbing it into their system. Again, this is optional, but I like to use it sometimes, especially if it’s a plant that I really care about.
Step 4: Treat Your Plant Again!
A week after you have sprayed your plant, go ahead and repeat the process again exactly like in Step 3 and spray again with insecticidal soap. Be very thorough in your spraying and soak all areas. This is important because you’ll want to kill the scale that hasn’t developed large enough for us to see.
Just because you don’t see them, doesn’t mean that they’re not there!
Step 5: Monitor Phase and Reapplication of Treatment If Needed
Lastly, monitor your plants regularly. Both the ones that you treated as well as any other houseplants you have in the area.
It is always best to treat any pests before they get out of control. Make it a point to inspect your plants on a regular basis in order to keep your houseplant collection happy and pest-free.
If you are curious about the lifecycle of scale, there is a great article written by the Entomology Department at Cornell University.
Curious about how to get rid of spider mites? Be sure to check out my post on treating spider mites.
I hope you’ve enjoyed this post on how to manage scale on houseplants. Have you successfully battled scale? Comment below. I’d love to hear!
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