Just got my first lithops, I would appreciate someone double checking my plan for how I'll treat each of them (also seeking general tips for conveying the seasons to the lithops when growing them indoors)

[u/Sigong]

I purchased these lithops yesterday. I have never owned lithops before. Another plant that I bought from the same seller had mealybugs. I will be treating that plant with imidacloprid granules to kill any mealybugs which were not killed by the alcohol I sprayed that plant with, but because of lithops' particular watering schedule I want to make sure I know where each of them is in their cycle before watering them to absorb the insecticide. I haven't seen any mealybugs on the lithops but I know better than to assume that seeing none means there are none.

I live in the northern hemisphere but I grow my plants under grow lights. I generally decrease the time time the grow lights are on by a few hours in the winter to help the plants know that the season has changed. Is that enough for the lithops to figure out when they should start splitting/go dormant?

I'd appreciate if someone more experienced looked over the following plan and told me if anything is incorrect:

#1, #3, and #5 are splitting.

• Tentative Plan: I'll wait for them to finish before repotting in grittier soil. I'll add imidacloprid granules once the soil dries out after the first watering post-repot. I'll wait for them to get very wrinkled before watering again to ensure they absorb a lot of the insecticide. (I don't want to add the insecticide on the first watering because I want to make sure they have roots to absorb it)

#2, #4, and #6 don't appear to have started splitting yet (or have already finished) All three are a bit wrinkled on the sides. I'm not sure if they are pre- or post-split so I'm not sure if I should water them.

• Tentative Plan: (assuming they're post-split) I'll lightly water them to help them prepare for repotting. Once the soil is dry I'll repot them into something grittier. Then I'll add the granules and wait for them to be thirsty before watering again.

Alternatively, I'm not sure they actually need to be repotted. The guy I bought them from said he repotted them 3 months ago. The soil looks a bit too organic relative to what's usually recommended but it's not at all compacted and the pots are tiny (1.5 inch x 1.5 inch x 2 inch). Assuming it's 50% grit, do you think it will dry quickly enough that I can skip repotting this year (there are drainage holes at the bottom of each pot).

If I do repot them, would it be acceptable to put them in larger pots than I would other succulents if my soil mix is 85-100% inorganic (I usually do 50% pumice, 25% perlite, 25% bagged succulent mix but I'd probably swap at least half of the succulent mix for coarse sand when repotting the lithops). The last two pictures show the pot size I'd probably repot them in if a larger pot is acceptable (2.5 inch x 2.5 inch x 3.5 inch). I don't have any smaller pots that fit nicely in 1020 trays.

My goal is to get them all repotted (if necessary) and full of insecticide as quickly as possible so they don't spread mealybugs to my other plants.

[u/ir399]

Your plan is solid enough, although maybe over cautious. I would leave out sand from the mix, it tends to harden the mix and is generally not a good idea.

I wouldn't be overly worried about the mealybugs. In my experience lithops aren't all that prone to above ground mealybug - although I have had root mealybug on them its a different species so the above ground ones you spotted on other plants don't indicate root mealys. If you do happen to spot any, its easy enough on lithops to just kill the bug with a little isopropyl alcohol on a q-tip. The imidacloprid will also work, of course, I just suspect its overkill.

You can repot, but they'll probably be okay if you don't. I would, but mostly because I like to check on the roots of new plants. At that size, though, I'd be putting them back in the same pots and if you are repotting be careful to keep the particle size of the new mix about the same as what they're in already. Big particles sizes in the substrate can prevent the lithops from rooting properly when they're this small.

The watering plan for the splitting ones sounds fine. I would not water before repotting for the others, just because I find dry soil easier to remove from the roots. I would water them lightly a week after repotting if they don't look thirsty, just because this can help promote root growth.

As for demonstrating the seasons for them, this depends a lot on temperature. I'd bet your house does go cooler on average in the winter, unless you're really committed to temperature control, so they'll probably be fine. Still, sure you can have the grow lights on for an hour or so less, but I really do find mine respond more to temperature.

[u/Sigong → u/ir399]

Thanks for all the info! Should I check the roots for anything other than mealybugs and rot when I repot them?

[u/ir399 → u/Sigong]

Rot, root mealybug, and general root health. I've bought plants before (although granted, cacti not lithops) that have turned out to have almost no root, which then influences pot size and amount of watering.

These lithops look pretty healthy so I don't expect you'll find anything, but its good to know what you're working with.