Treatment of Plants from Spider Mites: The Proven Way
Spider mites can reek havoc on your houseplants. They are very small and can easily go unnoticed until their population explodes. The first sign of having spider mites is webbing. They create and live in webs on the underside of the leaf and at leaf joints which makes it very easy for them to go unnoticed. Spider mites can come from anywhere. If you’ve bought a new plant, repotted in an unsterile soil, let your plants live outside a period of time in the summer, and/or brought in any fruits/vegetables/flowers inside from a garden... these are all potential sources of spider mites. They are also so incredibly small they can fit through window screening. Many of these instances cannot be avoided so the best practice for spider mites is complete, scorched-earth, eradication once you’ve determined you have them.
Step 1: Diagnosis
Spider mites will often cause your plant to become discolored or have crispy-edged leaves. If it gets to this point, you have a pretty large infestation. Ideally, you should be checking the leaves for pests every time you water your plants. Spider mites look like very small, fuzzy, salt crystals. Their webbing may or may not be obvious. They will be most prevalent on the underside of the leaf and near the leaf joint (where the leaf joins the stem).
Once you have determined the plant is infected, it should be immediately isolated from other plants to prevent cross-infection. You should also check the neighboring plants to see if they have already been cross-infected. A good rule of plant ownership is to always leave space between your plants; the leaves of one plant should never touch the leaves of another. Spider mites cannot fly but because they are so small, they can easily be blown around in the air. Avoiding drafts and leaving space between your plants will help minimize the spread of all kinds of houseplant pests, not just spider mites.
Step 2: Remove all dead and dying debris/leaves
Once isolated, any dead/dying leaves should be removed. Removing the leaves will allow the plant to focus its energy into its remaining existing growth and any new growth. When removing a leaf, don’t clip too far down the stem as a lot of new leaves can grow from an existing stem. Remove any debris at the base of the plant or on the top of the soil.
Step 3: Treatment preparation
Many guides out there say to shower down your plants with water to wash off spider mites but this does nothing to prevent or rid the plant of spider mites. The spider mite webbing is hydrophobic which means it doesn’t like water. Water will hit the webbing and bounce right off leaving the webbing, and the mites, intact. Simply showering the plant with water is not an adequate control. Additionally, if the sprayer is too strong it can damage the leaves.
Prior to starting a spider mite treatment, you will need a spray-bottle, drugstore rubbing alcohol, dawn dish soap, and a bushy make-up brush. Fill the spray-bottle 1/3 of the way full with drugstore rubbing alcohol, add a few squirts of dawn dish soap (go easy, you don’t want the bottle producing excessive foam), fill the remainder of the bottle with lukewarm tap water, and give the bottle a quick shake. Grab your make-up brush. If you don’t have an old make-up brush laying around the house, you can get one from the dollar store or any drugstore and the cheaper the brush, the better. Cheap brushes tend to be a bit more abrasive and that’s exactly what you want to use here.
Step 4: Treatment
Once your alcohol solution is prepared and your make-up brush is ready, give the plant an overall spray. This is a pre-treatment to loosen/soften any debris on the leaves. Do not spray/wet the soil directly as the alcohol-soap solution it is not good for the root system. Your spraying should focus solely on the leaves, which will not be harmed at all by the alcohol-soap solution
Lightly spray the brush with your alcohol-soap spray to get it wet. Grab a leaf and lay across your palm, face-up, so your hand is supporting the leaf. The leaf should already be wet from your preliminary spraying but if it has dried, give it another spray. Starting at where the leaf meets the stem, thoroughly brush the area. Brushing will physically disrupt the spider mites and their homes. With spider mites, you need to take a scorched-earth approach and simply showering the plant with water is not enough. Spider mites love to hangout in this leaf joint area so make sure to brush this area especially well. Work your way down the leave always brushing in the same direction as the leaf’s veining; this ensures you are getting into all the nooks/crevices. If you brush opposite direction of the veining, you will likely miss nooks/crevices and won’t have full coverage. If part of the leaf is damaged (curling/folded edges) make sure you brush inside the curl/folds as mites will hide there. You want to makes sure the entire top of the leaf has been brushed.
Once the tops of all the leaves have been brushed, perform the same treatment on the underside of the leaves. The underside of the leaves will have the heaviest spider mite prevalence so be sure to cover the leave edge to edge always going with the vein. You can also brush a bit of the stems to full coverage. There should be no portion of the plant left unbrushed. If there is, that’s is where the spider mites will migrate to.
Step 5: Follow-up
A single treatment is not enough to eradicate spider mites. This process should be repeated every other day for a week (Day 1, 3, 5, and 7). Once completed, the plant should sit in isolation for a few more days before being moved back to its original spot.
Pro-tip 1: If a bushy plant with a lot of leaves is affected (e.g. pothos) it is very easy to lose track of which leaves you treated and which you haven’t. For bushy plants, you can run a piece of string through the plant keeping ‘dirty’ leaves on one side and ‘clean’ leaves on the other. After you’ve cleaned a leaf, move the string over that leave moving it to the ‘clean’ side.
Pro-tip 2: If you are bringing a new plant into your home, it’s a good idea to do the full-treatment as a preventative measure. It’s also a great idea to do a single treatment as part of your routine plant care.