I have a shit ton of plants. A few months ago I brought home a rare plant, which in my excitement to acquire I apparently didn’t inspect closely enough. Now all god’s chillins got spider mites.
Looking for home remedies I find basically two different recipes:
–one includes, among other ingredients, vinegar and baking soda
–the other includes soap and oil
Don’t those pairs of ingredients cancel each other out?
I’ve used a mild dish soap solution to kill the little mites on my Carpenter plants (silphium).
No oil needed. SFGate seems to have reasonable destructions.
No oil is needed.
I don’t bother rinsing my Carpenter plants, and nothing awful happens. Your plants may be more sensitive.
Get as close to plain vanilla liquid dish soap as you can.
Soap is a good wetting agent, so it’ll more easily cover the mite’s breathing pores than mere water.
Don’t even bother trying baking soda and vinegar. That’ll just get you sodium acetate, and fizz; nothing deadly to bugs.
The soap and water trick has been around and used successfully for decades.
Yes, thanks, understood. I was looking for answers about the chemistry: Do soap and oil cancel each other out? Don’t vinegar and baking soda cancel each other out?
Soap could serve as a solubilizer/dispersant for small quantities of oil, if you’ve got a particular oil that kills mites, but generally you are correct. Soaps are used to wash away oils. Their presence decreases the surfactant power of soaps. I’d call the soap oil mixes hogwash, except that there might be some specific oily toxin out there that needs to be dispersed in a soapy solution in order to be effective.
I can’t imagine a mechanism whereby sodium acetate would kill a mite, unless you drop a big hard chunk of it on the bug. As I said before, as surfactants, soaps make it easier for water to clog up insect’s breathing pores. That’ll kill them.
Yeah all pretty much what I was thinking. Thanks!
Repeatedly hosing off plants with water with attention to undersides of leaves, if done repeatedly, will kill off spider mites.
Insecticidal soap, horticultural oils, or hort.oil solutions containing enough soap to get the oil dissolved properly in water will work, but repeat sprayings are needed.
Heavily infested plants i.e. with visible webbing might be best discarded.
There are specific miticides which require greater caution in handling.
Soap is technically an emulsifier, which, rather than destroying oils, merely allows them to be mixed with water. This makes cleaning easy because oils get suspended in water, and don’t get re-deposited on the thing you’re cleaning, but get rinsed away by more water.
Vinegar and baking soda do ‘destroy’ each other, in the sense that they chemically combine to form a new molecule with different properties than vinegar or baking soda individually. For some reason DIY sites seem to think the fizzing actually does something like clean your toilet or unclog a sink.
I thought that soaps did something directly to the insect cell membranes and caused them to dehydrate, while oils directly suffocate them. I imagine that someone got the “bright” idea to combine them thinking that it would be extra deadly, when in reality they basically cancel each other out.
Either way, you can get either commercially- examples are Safer Insecticidal soap or Volck horticultural oil.
I’d just go with the soap myself as it’s least harmful to the plants- ideally you’d want actual soap, not detergents like dish liquid or shampoo.
As a gardener who has been through this in previous years, I would recommend a backup plan. I tried hosing them off, tried neem oil, tried insecticidal soap and horticultural oil. Either I missed the aggressive schedule required for the above methods or I had super mites or maybe both.
What worked for me finally was imidacloprid granules ( systemic insecticide) applied to my houseplants/ornamentals and it got rid of them very quickly. May not be safe for fruiting plants or plants used in foods. Please do your research.