All of my oncidiums seemed fine in semi-hydro if timed with the start of the new growth so it seems fairly safe. I also found cattleya divisions with few roots a good choice.

I removed my phals from semi hydro as I did not like the direction things were headed. They can be converted to semi hydro but I couldn't adapt mine. The new roots stopped growing when they touched the leca so they're just little stumps while the old roots died - leaving me with nothing to support the plants. I prefer water culture or sphagnum moss for phals but I just chalk it up to experience.

My dendrobium nobiles are growing in semi water culture now too and they seem to really like it. They are very easy-going so probably would have been fine in semi-hydro - but I could not get them to stay upright in LECA as they're very top-heavy!

Hi there I know your post is from some time ago, just wandered if you still doing ok with SH with your orchids. I am also in UK and wished trying SH or water culture. Have you got any in full water if so how is it going. Thank you very much in advance.

I have been trying again with converting my phalaenopsis into semi-hydro during the warm summer and had much better results than I did moving them during winter. Phals are the only ones that I found tricky but if they have nice healthy roots then they seem to do a lot better.

I have done full water culture in the past and it does work but washing the vases is a pain. I dislike the murky water. Also, I think orchids benefit from attaching/securing themselves to their growing media so I prefer semi hydro.

Thank you so much for replay. Well have to wait until summer then to try it out :)
It is nice to compare growing with people living in the same enviroment as your self.

You may find it easier to convert phals in the summer, because of the temperature, but I'd still be wary of doing so if the winter temperatures in your growing environment cannot be called "quite warm."

For the most part, phalaenopsis are warm- to hot growers that can tolerate our preferred temperatures reasonably well. However, if they are exposed to cooler temperatures with damp roots, they will suffer, and if the combination of lowered thermostats and dry air leads to evaporative cooling, pushing the temp even lower, the roots can die.

I have moved my phals out of the original room they were in, which is hot in summer but cold in the winter. The rest of the house is consistent in temperature except that room (it's a converted attic bedroom).

I had such consistently good results on more intermediate types like cattleya/oncidiums that I was a little complacent with my phals. I will see how it goes this winter and will focus on warmth and good light. I have a new LED that I keep in a spare bedroom away from the windowsill that they might enjoy. From observing my phals, I think part of the problem was the poor timing as well.

Even though they came close, none of my phals died. The new leaves emerged small due to their poor health but they have new root systems now and the leaves are growing bigger. A few are blooming away.

I have placed a paph and a few other oncidiums/miltoniopsis/cattleyas into S/H so I look forward to sharing my results. My paph seems fine after a few months. I do have a cattleya that was rootless for almost a year. It was doing nothing. It started to root quite soon after placing in S/H. It seemed to sense something....

Hi Ray thanks for your replay. I might leave phals where they are as I am doing real well with them in bark and seramis mix, some are in Leca and seramis but not SH and they also are healthy. It is oncidiums and cattleyas that I am thinking of moving to SH, but will listen to you guys and wait until spring.

The wait should not be based upon season, but upon the emergence of new roots from the base of the plant.

That often IS seasonal, but not always, and the issue can be forced with prudent use of plant growth stimulants.

Updates
 

I've been a bit quiet on the S/H updates lately. This is because I was trying new orchids and gathering more experience with my existing orchids (especially recovering my phals). I have a renewed interest in S/H and have converted more orchids.

I want to start by discussing old mistakes and add some new experimental S/H candidates!

First, let me update the phals. Good news this time!

A year ago, I converted my phals to S/H in a cool climate at a low light time of the year (autumn/winter time). This was a big mistake and although they all survived, they did lose all their roots. They are getting healthier though and the leaves are now growing to a more reasonable size. Last year, I was continually experimenting on them, repotting them and disturbing them until I ended up in a downward spiral of root loss. I recovered them for a few months in sphagnum and tried again. I converted much healthier orchids with nice, healthy and INTACT roots. I suggest putting a phal like mine with messed up roots into moss so it can grow some nicer roots before attempting conversion - as there is no pseudobulbs and some nice roots deep in the LECA beads will help a LOT. Otherwise, everything dies and you just have a dehydrated mess on your hands. I currently have 18 phals growing in semi hydro but I have to say they have been my most challenging conversion.

https://farm5.staticflickr.com/4558/...7c1cf0b1_n.jpg

The next phal was completely rootless last winter, it lost about 8 leaves. It's now happy in semi hydro, LOL. It has bloomed, despite having very small new leaves they are getting better.

https://farm5.staticflickr.com/4524/...25141fea_n.jpg

https://farm5.staticflickr.com/4483/...7878a842_n.jpg


Now, issues:

Root tips. The roots above the LECA don't dig down very well into the media.

Unexplained root tip death:

https://farm5.staticflickr.com/4463/...df673b5a_n.jpg

Shrinking, dying root tip:

https://farm5.staticflickr.com/4490/...5cbd875c_n.jpg

I am genuinely afraid for these root tips as I don't know what to do to help them except mist them when I have time. I love how they curl around in the deeper layers but the surface roots do not do well for me and was part of the reason I had so many troubles last year - even the phals with new roots were left with just a few short stumps above the media!

https://farm5.staticflickr.com/4525/...df9ef13d_n.jpg


The next orchids:

Cattleya seedlings!

I love these! These are both RLC Liu's Joyance

https://farm5.staticflickr.com/4541/...96552eda_n.jpg

They arrived in a coconut shell and were pretty mangled when I freed them. As you know, cattleyas are a bit funny about their roots and they didn't really have anything very good on transferring over. They were masquerading as a single orchid but once freed from their coconut prison, it was two extra small ones together. They immediately took off in semi hydro without any issues.

Roots:

https://farm5.staticflickr.com/4510/...21f94756aa.jpg

These are all new and I don't know if the photos actually show how small these seedlings are.

Another cattleya seedling: BLC Nakornchaisri delight. Again, trapped in a rotting coconut.

https://farm5.staticflickr.com/4455/...5b8a1798_n.jpg

As you can see, there are no weird root tip death issues here and I have not experienced this at all in the cattleya alliance. It looks a bit lopsided but that is just how it grows and it is very secure in the media (I could probably lift the whole thing by the orchid but it's a delicate seedling so I won't!).

Roots:

https://farm5.staticflickr.com/4479/...087dfcaf_n.jpg

As you can see, I do not manage my algae very well. I just ignore it for the most part. The roots are hard to see but they're alive and doing well.

Cattleyas show a huge amount of adaptability in their old VS new roots. Where the old roots are completely unable to cope in the new medium and the new roots are completely different and actually thrive in constant wet conditions. With phals, however, sometimes if you have a good, healthy, growing root you don't always lose it. If it's old and broken up/cut etc it will have quite a low probability of survival.

I have plenty of other orchids to discuss!!!

My future posts will cover vandaceous, adult cattleyas, den phals, den nobiles, paphiopedilums, miltoniopsis and more on oncidium intergenerics (if you haven't had enough of those yet!). I have my first catasetum-type (cycnodes wine delight) which may end up in S/H.

As you can see, I have been orchid shopping this year!!!

Happy growing to all and I hope your orchids are thriving, however you decided to grow them!!!

Good work. I suspect the Phal root loss is due to insufficient watering, or those were old roots that didn't adapt.

If the water doesn't wick up far enough to keep the top of the LECA moist roots up there will die unless you water fairly often.