Probably both. I've never heard of reducing the roots to stimulate new growth. May I pls ask where you heard that? Doesn't seem a great idea to me. This seems ill advised to me, esp going into Winter.

I also wouldn't use potting soil in my mix, it's too rich & water retentive, I'd use C&S mix instead for the soil portion.

Seems fair to assume far less roots would take up far less water.

I have a number of Sansevierias in a combination potting mix similar to what you described -- some soil, some perlite, some pumice. Often, it is not an exact measurement. I kind of aim for what looks "visually" right to me for the particular plant. Also, I have a lot of my mature Sans in plastic pots with this kind of mix.

However, I rarely do the level of root pruning that you described. I will root-prune if I have a bunch of dead or dying roots. I'll also root-prune if I'm trying to repot into essentially the same size container as the old one. So -- it would seem to be that if you removed 80% of the existing roots, most of what is in the pot is soil mixture, not Sans' roots that can absorb moisture.

That said -- I am in SW Florida and my Sans, described above (soil combo mixture, plastic pots) get watered in the summer, when it's hot and humid, about once every 2-3 weeks and in the winter maybe once a month. And my soil mixes in plastic pots DO STAY MOIST throughout those times. BTW, sometimes I top dress, other times not. It WILL help keep moisture in the mix, so -- factor it in also, in my opinion.

Thanks for the replies. We’re not going into winter, we’re going into summer so that’s why I usually repot in october or november. I always prune the roots when I repot, but I guess I did a little bit too much this time. Anyways, the soil is now finally drying and there shouldn’t be any risk for root rot considering the 50% perlite in the mix, but I think’ll try a 60-40 mix with perlite being the main ingredient the next time. My potting soil is perfectly well suited for succulents, but the 1cm thick layer of top dressing prevented it from drying out as quick as my mix usually do. The plants look awesome with top dressing though, so I’d like to continue that way. I will try a 60/40 mix with perlite/potting soil next spring though to see if that makes it drain even better.

Regards

Edinburgha

Think about something. The purpose of perlite is to aerate the soil. If it's floating to the top, then it's purpose is nullified. In order to work it would have to remain mixed in the soil, but since it floats, it is useless. Use regular soil without it, or find something gritty to mix in instead

Still, perlite is Gods gift to succulent growers. It provides aeration and drainage, making root rot almost unheard of. I’ve found that it does take a few days extra for the mix to dry out with top dressing, but the dressing keeps the perlite perfectly mixed so I think I’ll keep it this way nonetheless.