Have you confirmed the presence of spider mites? Any webbing evident? Spider mites (and aphids) are sucking insects - they do not make visible holes. btw, neem oil is registered as a miticide and should be effective, although could well require repeat applications. Sulfur and whatever plant oil you choose to mix with it are not and will have limited effectiveness, if any.

Thank you! I've seen the webs, and the spiders. :/ I've also seen aphids.

Mites are not spiders and they are almost invisible to the naked eye they are so tiny. Impossible to see on the actual plant. Aphids are a good 5-10 times the size of spider mites. Also, their webbing does not look like a spider's webbing. It is a dense, fluffy substance located under the leaves and in stem joints.

You need to make sure your diagnosis is correct before you apply anything.

Don't mix oil and sulphur; it will burn your plants. Yes, it can be used on edibles. Don't know the answer to your question about dilution rate. I've always used Fertilome sulphur and it might be different.

You might ask this on the Hoya forum. I know many Hoya growers had to spray their plants with sulfur for flat mites.

If you can see actual spider webs they are not spider mites. And true spiders don't make holes in plants. They eat the things that make holes in plants. You need to id the problem before attempting treatment.

Sulphur is a fungicide, not an insecticide.

If you could post in-focus close ups of what you think is wrong perhaps the problems can be diagnosed. Some of the issues look more cultural than pest ie soil, feeding, watering and pruning.

Sorry; I've been out of town! Here are some close-up pics of the webs (olive, thyme, succulent), and some of the droppings (?) (not from spider mites obv) on my calibrochoa.

ETA: Problems definitely could be cultural rather than insects, mites, whatever! I'm not a great gardener. :P