Is mineral oil toxic for orchids?

[Maru777]

Hello everyone,

I have a question for the more experienced growers and that is: is mineral oil toxic for orchids? To explain, I left my orchids in the care of a friend while I was away for a few weeks. During that time I had a thrip infestation (well spotted by my friend, I can see the damage on the leaves) but right before I came home she decided to take matters into her own hands and sprayed them with mineral oil aka baby oil. Now, I don’t know just how much of it, but they look mighty glossy and smell of lavander This was two days ago. None died yet and I showered them with water to clean some of that off but now I am not sure if I should take more drastic measures or prepare mentally for a bunch of them to die.

Thank you!

[estación seca]

I don't think it's been done like that very often.

Oil sprays are used successfully with orchids for killing arthropods. If it's a brief exposure and not too often it is probably not harmful. It's not good to repeat oil sprays though.

[Roberta]

The oil has had a chance to do its work. If you want to get it off the leaves, maybe add a bit of dish soap to the water that you spray on the leaves. Water alone won't remove the oil, but the addition of soap will (just like on dishes) And the soapy water also kills thrips and other insects (and arthropods like spider mites too.)

[Dusty Ol' Man]

Just remember that mineral oil is nothing more than highly refined petroleum lubricating oil. Personally, I'd be wary of using petroleum products on my plants. I work in the petroleum industry and have read the SDS for many of these products.

[Roberta]

People do use baby oil on their babies... I'd have to suspect that there's not much bad stuff in there. But still a concern that it may plug pores in the leaves, washing it off is probably a good idea.

[Dimples]

Like everyone else has said, a one time application of mineral oil probably isn’t going to do major damage to plants that aren’t oil-sensitive, especially indoor plants where temperatures are generally in the correct range for safe use. Use a dash of soap in some water and wipe heavily doused leaves and spray any lightly covered and delicate leaves, followed by a thorough rinse with water.

[Optimist]

I'd be worried about clogging the stomata. I do not know if the oils used in plant treatments are water-based (is there such a thing?)-- or will wash off with water. Neem oil is 100% natural, biodegradable, water-soluble.

[isurus79]

Insecticidal soap or neem oil will do the same thing to the pests, but without the downside of using a petroleum product on your plant.

[Dimples]

I like neem and insecticidal soap, but horticultural oil is fantastic too. It’s a very safe non-selective pesticide and often my go-to when I’m dealing with semi-mystery fungal or pest issues. The fast-ish evaporation time (compared to a heavier plant based oils) also minimizes incidental harm to beneficial insects.

More info:
Horticultural oils are typically petroleum products. Newer pesticide products sometimes use plant based oils but those are less common and are typically a bit heavier and leave more residue than petroleum based hort oils. An oil being petroleum based isn’t a problem so long as it’s designed to be used on plants and is used at the correct time/growth stage and under the correct conditions.

Hort oil will evaporate off leaf surfaces as it dries because it is a very light oil, which is why it must be used at specific temperatures and environmental conditions. High humidity and cold temperatures will both slow drying and could result in extended contact time, which can damage some plants. Low humidity and high temperatures both speed drying (as does wind) and can decrease the effectiveness of the pesticide by reducing the contact time, but oil used when temperatures are too high can result in phytotoxicity damage. This is also true for plant based oils.

Dormant oil is just a heavier weight petroleum product that is historically used on dormant deciduous plants that don’t have any foliage to be damaged (eg. fruit trees in winter). The heavier weight of the oil increases the pesticide effectiveness because of increased contact time, but the oil still evaporates off plant surfaces eventually.

[Maru777]

Thank you everyone!

I have washed them all with soapy water and then rinsed them off with clean water so I hope they will be ok. They still look a bit suspiciously glossy but so far no other concerning issues so I’ll monitor and see. I do have neem oil, and insecticidal soap. Nothing stronger because it kills the little frogs in the pots and I haven’t the heart for that. But by the time I came back the deed was done with the baby oil. I think her thought was that since it’s for babies it will be less toxic than other things - I had no idea it was a petroleum derivate! Live and learn! I can’t even be upset, her intentions were good. The downside so far seems to only be that having to wash them all up I had to own up to the fact that I have a lot of them. Nobody tell my partner, he does not need to know I admitted such things