Repotting a catasetum-type? - Orchid Board

malteseproverb · #1 02-02-2017, 03:10 PM

I have a Monnierara Millennium Magic 'Witchcraft' that I've left completely dry since the leaves fell off around October. It has a new shoot which I just measured to be 3", so I know it's time to resume watering. What I'm wondering is if I should repot since there is new growth right now, and if so, (1) what should the media be, and (2) what size pot? This is my first catasetum-type orchid in general and I bought it in late summer.

From photos I've seen googling this orchid type, it looks like two fully grown pbulbs can fit in the size pot I have now, so it seems possible to simply leave it alone. I've also read that it doesn't like its roots disturbed. From what I can tell it's currently potted in primarily sphagnum moss. It seems very happy: this shoot grew rapidly, I had no problem with it going into dormancy and it barely shriveled in the months I haven't watered it.

In terms of my growing conditions: east-facing bay window with lots of sunlight if it's sunny, hot in the summer (75-110F), cold in the winter (57-68F), RH around 50-70% with my humidifier going. I might hang this one outside this summer.

Anybody have experience with repotting this orchid or catasetums? Anything I should know?

Roberta · #2 02-02-2017, 06:19 PM

Not quite time to start watering yet... you really want the roots to be 3" or more before you water, the roots are just getting started. If it were my plant, I'd move it to a bit larger pot... the new growth, if it does what it is supposed to, will be bigger than the large p-bulb, and so will be climbing out of the pot. Spaghnum is fine for this size and one size larger. Beyond that, I like small bark better. When you repot, don't worry about getting the old sphag off. Just add more, to accommodate the slightly larger pot. Don't worry about harming the old roots - it's the new ones that you have to worry about, the old ones don't do much. So get it potted now before the roots get significantly bigger (just getting started) The new sphagnum will have to be damp to work with it, but should not be soggy. and then, forget it for another few weeks or maybe a month. Fred Clarke (Sunset Valley Orchids) suggests waiting until the second flush of roots appears - good advice, because once the first batch get down into the pot there is no way to tell how long they are. but at this stage, with a small new growth, it's especially important not to get water down into it - that is a really good way to rot it. With that big fat p-bulb from last year, it has plenty of reserves to get going without any water yet.

Subrosa · #3 02-03-2017, 03:26 PM

I repot every year when the new growth starts getting roots. I use a layered substrate with the bottom 2/3 of the pot full of organic humus from a garden center a sphagnum on top. This lets the roots get well developed before they hit the constantly moist and nutrient rich compost layer.

malteseproverb · #4 02-03-2017, 03:44 PM

Wow, I read the thing about repotting when the shoot itself is 3" on many sites, they never said anything about the roots! I'm glad I posted as I was about to water it. I'm happy to leave it dry for another month or whatever it wants. I was thinking it was a bit early for it to be coming out of its dry period. I will repot soon then and see if I can find a slightly larger pot that is hang-able. I'll also try to see if I can find anything a little more nutritious than sphagnum. I like potting in layers in general, I've found it to be effective with other 'chids that like to be wet. Thanks everyone!

estación seca · #5 02-03-2017, 03:59 PM

Go to Sunset Valley Orchids and read the page on Cultivation of Catasetinae. Many of us have plants making new growth right now. We won't water them until the roots are long enough - Memorial Day or later. These have a very different growing pattern from most orchids.

Roberta · #6 02-03-2017, 04:15 PM

Quote:

Originally Posted by estación seca

Go to Sunset Valley Orchids and read the page on Cultivation of Catasetinae. Many of us have plants making new growth right now. We won't water them until the roots are long enough - Memorial Day or later. These have a very different growing pattern from most orchids.

Right on. Here's the link Sunset Valley Orchids - Catasetinae Culture

Fred Clarke is one of the top growers of Catasetinae (I think he knows about as much about them as anybody on the planet). If you have further questions, send him an email from the website - he is very willing to share his knowledge, and can advise if you have a specific situation that isn't covered in the general culture notes.