do not trim the roots - this will rot both, the roots AND the tuber. washing the roots with water is not recommended either - it can also rot the roots. i did both ;) AND killed my absolutely florishing huge bursting out of pots ZZ plants that i had for 5 years.
and i am an experienced grower with a very large collection of plants ;).
the soil needs to contain a large amt of bark/perlite to drain well and be on the dry side. donnow about miracle grow - it should be cut with more perlite most likely. but it's too late now. do not water them until you are sure they are bone dry. they do best pot bound.
does the soil bag state the contents of mix? just how much peat/compost is in it, do you know?
picture?

am curious about differing opinions? on what point exactly?
yes, bare-rooting with repot works for a lot of plants, BUT is chancy for ZZs. NOT trimming OR washing roots - that's a must for ZZ. unfortunately i found that out AFTER my disaster :(.
i posted in detail about it in the following link (grab posted similar observations - he's a very experienced aroid grower).

Here is a link that might be useful: the fight for my zz's.

there's a good and very long thread here about zz's. bradleys plants have done phenomenally, even though it's his first zz plant.
plantomaniac repotted his with bareroot into free draining bark and they still rotted. i used first jungle mix with lots of bark, then repotted in pure orchid bark after the 1st month too in hopes to stop the rot! - no such luck.
i managed to save just a few tubers with a couple stalks each - it's been almost a year now, they have a few roots and no new stalks. i put them in water of all things and then xfered in hydro with perlite/coir. all else was failing: first roots would grow and then they would rot...i got tired of checking and trimming and potting up ev.month.
yours is very large. give it good bright light if you can. the growing season is upon us - spring/fall is when they really shoot out.
if you notice leaves/stalks getting yellow - that's the sign of rotting roots/tubers. check first with your finger around the stalk/tuber to see if it's soft/mushy. if so, you'll need to get it out of the pot to prevent spread.

Here is a link that might be useful: zz fun

petrushka,
Just to let you know, I am a female. ;) But yes, I washed my ZZ Plant's roots (it was in crap soil and that was the only way for me to remove the soil) and even had quite a bit of perlite in my new potting mix. I admit, I've tried three times and they've all rotted on me. The first one I left in the crap soil and put new soil around the rootball. It rotted from the inside out because the original soil was so water retentive. Second and third time I figured I should clean off the soil and repot in all new soil. Both sets rotted. I just can't win. I've given up.

I'm sorry to the OP, this probably scares you more in repotting your plant. I'm not the best to give advice on this. I've all but given up on ZZ Plants.... Sadly too, I just love the way they look. I hope you find the answers you're looking for, sorry I don't have them.

Planto

Hey Planto,

I'm sorry to hear this. I grow mine w/ C&S mix to which I add abt 1/3 volume pumice or perlite. Each of my 2 just had a new shoot. I basically ignore them like most of my C&S & they do fine.

A third one I have rather high up & completely ignore. It barely gets water. When I watered it last week, I found a new shoot coming up from the mix. Mine really do seem to thrive on neglect.

PG,
Thanks. :) I forget, did you mention before at some point if your ZZ Plants were grown from leaves?

Maybe that's what I should do as I was able to propagate a couple from leaves (a tiny clay pot with fast draining soil wasn't the best idea though, they dried out way too fast and died).

I had about half C&S soil and half perlite for my last two ZZ Plants. I still don't understand what went wrong. I guess it's possible they are one of those plants that detest having their roots messed with.

Maybe if I start one out in a good mix and not have to fuss around with cleaning the roots in order to replace a bad potting mix, it'd survive. Oh I love the sound of yours. I don't try to baby my plants (that's hard to do since I'm in between jobs, sadly) and try to find plants that can thrive on neglect (as I won't be jobless forever and don't need fussy plants).

I'm still tickled you offered to let me have one of yours, but even at this point in time I don't have anything I could offer as a trade. And although I'd feel giddy every time I'd look at it considering it'd be from you, I'd feel horrible if I somehow killed it.

Again, thanks for the information and condolences.

Planto

sorry, planto my bad :). though i think there's another planto there. whose gender i don't know either ;0.
i don't understand what went wrong with mine either (except for washing and cutting that is, LOL).
but i'd think that trimming all rotting parts and dusting and plunking it in almost dry bark for a mo without watering would fix it, no? it did, but only after 2mo! and then some of it finally produced great roots! but i watered it (@?!&> and it rotted again... silly plant!
but NOW it lives in damp perlite just fine!
the stalks cut off at the bottom produced tubers! in a few months. in water! see for yourself.
i truly do not understand it. it was so-o easy for 5yrs...and then it turned into a beast.

petrushka,
Lol, it's okay, you're not the first to think I'm a guy. For the longest, I thought Toni (hopefulauthor) was a guy. That's crazy, you grew tubers from stems in water, but it rotted in soil! Hopefully you will get your plant to it's former glory one day. :)

Another Planto you say? I must meet this Planto!

Planto

This post was edited by plantomaniac08 on Sun, Mar 2, 14 at 19:06

Thanks everyone! What is C& S soil please? I looked at the ingredients of my soil mix and it said bark (pine I think), two kinds of peat and dolomite. I chose it because it was quick draining but I confess I haven't paid much attention to soil in the past, using Miracle Grow potting soil for most potted plants indoors and out. I've had pretty good luck, though I try to stick with easy to grow plants indoors. The ZZ Is my favorite and I've had great lluck with the two I just potted up. So far no repercussions from what I did and I had to saw around the pots to detach the roots. I thought I was going to have to break the pot, then read about using water to loosen them and it worked. Because they roots were such a tangled mass, I washed the dirt from the bottom and outer ones. I did the same thing on a slightly smaller one, which is also doing fine so far. I considered trimming some of the roots but was afraid ... Later I read the lengthy article here that said root pruning was healthier than just potting up! I am so uncertain but prob should leave well enough alone and just tolerate my huge pot ....

Sorry, C&S refers to Cactus & Succulent, either the Forum nearby (see top of page) or in this case I meant it as a type of commercially available soil mix, one supposedly intended for Cactus & Succulents.

Yes, Planto, 2 of my 3 ZZ plants were grown from single leaves. I think one of those I then rooted from a single plantlet in water, which sprouted a green pea-like tuber & w/ it a single root.

ZZs seem to generally be pretty slow growing plants except for Bradley's ZZ & its story posted here somewhere. That particular plant which bloomed for him several times, seemed to grow unusually fast for him.

ZZLover,
Yes, PG said it before I could. Sorry for the abbreviations, I forget not everyone knows what I'm talking about. :P

PG,
When you say "plantlet" do you mean a stem? That sounds interesting. Bradley's ZZ Plant... don't get me started on that plant. I already told Bradley I was jealous of it lol.

Planto

Thanks again! I've been doing more internet research and it sounds like some root pruning is safe as long as you don't damage the tubers. Apparently it is also possible to divide the plant, again being careful not to damage the tubers. I am going to wait another week or two before tackling this project because I want it to dry out and also to have recovery time since I've read that any repotting is traumatic for any plant. I have also moved it inside and it is likely not as happy as it was on my lanai. When I do it, I will change to C&S soil. I'm not sure perlite is necessary ... Some say sand but I haven't read what is in the C&S mix. I will keep an eye on the other plant but if it shows no signs of distress, I may leave it in the quck draining MG bougainvillea mix. I am satisfied with just the "potting up" of that plant since it is not yet unmanageable. I'll keep you posted! Happy ZZ growing!

No sand, at all, ever, will compact in your roots & contribute to rot. Sand is asking for trouble for sure.

ZZLover,
Perlite was suggested because it adds to drainage. PG uses pumice instead of perlite (which I've read is better than perlite, but I don't have access to pumice).

Sand does compact as PG stated. There is a myth out there that sand is good for cacti because it drains well. Well... have you ever seen wet sand outdoors? You can literally scoop that stuff up and it stays one solid wet mess. It does compact. I don't think most C&S soils have sand in them... if they do, it's so far down on the list it's miniscule.

I hope you've found our information useful. Let us know what you end up doing with your ZZ, it looks like one happy plant!

Planto

Planting anything in crap is probably a poor choice. Would you live in it?

When replanting a ZZ plant, how deep is the bulb? Do you comber the bulb to tuber with soil, or leave the top uncovered? There were three plants in the pot. I replanted it and one plant has rotted. Thanks!

I leave the top half inch of the tuber exposed.