Today I thought I would gently clean the leaves of the two schefflera plants. The dull look of the leaves isn't from dust. After some investigation, I believe they have spider mites. Tomorrow is supposed to be around 60 degrees here. I thought I could take them outside and hose them down then follow-up with a dishwashing detergent spray. Do you think this is a good idea? Would an outside spraying in 60-degree weather be bad? Do you think I can get the mites under control? Or is this going to be a constant battle?

I need to decide if these plants are worth saving. I only had 3 other houseplants before these new arrivals. My other plants are in a separate area of the house so hopefully they will not come in contact with the mites. (How close is too close?) These scheffleras are big, but probably not the most beautiful. They both have 3 stems in one pot (typical "gift" plant). One is over 5 feet tall. The other is around 3 feet tall. Later this summer, I planned to work a little with them, maybe repot each individual plant into a separate pot and see if I could encourage them to grow a little fuller. If I mess up and kill one, at least they were free.

What would you do?

Thanks,
MB

Though it's possible to gain control over the mites, they are almost impossible to eradicate. It will be an on going battle.

You might do more damage to these plants by trying to separate them (think of the fragile root system). Whenever I've propagated plants (of many different kinds), I've used at least three cuttings per pot as a norm.

The alcohol provides immediate knockdown and the neem is an anti-feedant and chemosterilizer (stops them from reproducing). It also short circuits the development process.

Al

Not that it's impossible to eliminate mites on a single plant, but as rhizo_1 says, they travel, and all it takes is for one pregnant female to survive and then you're right back where you started by April. I also agree with rhizo that you're probably best not to try to separate the individual plants, if they've been growing together this long already.

If you do decide that you want to try anyway, 60F/16C is warm enough, but not by a lot, especially if it's windy or if the water out of the hose is very cold, or both. If they were my plants, I'd be more inclined to keep them inside, and just hand-wash both sides of the leaves with paper towels and dishwashing liquid, then rinse them off in the shower (works best if you have a detachable showerhead that you can use to spray the undersides), then hand-wipe with paper towels again, then rinse in the shower again. You don't have to buy anything that you don't probably already have around the house, and there are no weird smells to contend with.[1] This should at least keep the populations manageable, without getting the plants too wet, and in between showerings, you can soap up the leaves every five days or so to catch any newly-hatched mites before they have a chance to reproduce.

Whatever you do, you're going to have to work on it consistently, for a few months, and even then, you're still going to need to watch the plants pretty closely for signs of new infestations.

So like I said, I'd be more inclined to just skip the whole thing entirely. Scheffleras are common enough that if you really want one, you can get a brand-new, miteless[2] one relatively cheap, and if you don't really want one, then you're better off without any, whether they're free or not.

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[1] Although I'm usually fairly smell-tolerant, I have a personal problem with neem oil. Or at least sometimes I do: part of the time, it just smells kinda funny, and the rest of the time it smells like rancid peanut butter that someone has eaten and then thrown up, which makes me mildly nauseous myself.
If the smell doesn't bother you or anybody you live with, then yes, it's probably a better way to go than soap and water. And the smell does dissipate within a few days.
[2] (In theory.)

Al

Al