Moving Catts to s/h. Clarification and Opinions Needed!

[emmajs243]

Hi guys! Definitely looking & hoping for some experienced s/h growers to weigh in on this post!

I live in Idaho, where the orchids are they stay at least at 72 degrees during the day, usually more like 78 and at night I have been giving them the gradual temp change to mid 60s. This is only because I have read catts need that temp change...In addition, they are all on seedling heat mats and humidity stays at least in the 50% range normally more in the 60% range. There also is a fan rotating constantly on a low speed throughout the room just not directly hitting the orchids. I only point it directly at them after watering to ensure any rogue water drops quickly dry.

It took me a while to figure out what temp/humidity/air flow balanced was needed to keep a s/h set up running correctly, (primarily I have had to find a balance that doesn't cause the top layer to dry it too quickly) BUT after lots of adjusting, I finally have found a balance for my home! Oh and they get indirect south & east sun basically all day.

Currently all catts are in bark/perilite mixes (just what the sellers had them in). I fertilize weakly weekly but it seems like my catts are total water lovers. I have been really concerned about over watering so it has taken me a while but I finally upped watering to twice a week. The pot weight always has felt dry after 3-4 days but finally I stuck my finger 1/2 an inch or so into the bark in the center of the pot and it seems like it is constantly bone dry.

In addition, I recently got some cattleya seedlings (2&1/2 in pot size) and I was advised to not let them dry out completely between waterings but aim to water right before they dry out. So far, it seems like by the 3 day mark their pots are also bone dry.!

This is where s/h comes in. I am needing to repot them here shortly and I was trying to decide if now that I have my s/h set up tested and approved, maybe they would be happier in s/h since it has been such a struggle to keep up with their watering. Now don't get me wrong, I had plans to change everyone to s/h once I found I could successfully provide the right environment for the system to function properly, I just have been a tad timid to moving my Catts over to it.

So first, does anyone have opinions or experience with catt seedlings in s/h? Are they too young to experience such a large change? If there even is such a thing? I don't know, these are my first seedlings so I am just a little over cautious.

Second, as mentioned, I have been giving my orchids this day/night gradual temperature change like so many culture sheets advice. Would I still want to do this in s/h? Well or at the same temperatures? My concern is cold evaporation primarily. Should they be ok due to the heat mats?

Third and maybe the biggest one, I just want to clarify and get some, additional opinions on s/h and the best time to transfer orchids. I know the current root system most likely will not Be capable of adapting and will rot so you want good new root growth so these roots can grow to handle s/h's environment. I also have been told that you need to take care to repot catts at the proper time or else they will not be too happy.

I guess where I am getting tripped up is, when researching and reading the best time to repot catts, they show this photo of a Catt with like 10-15 little root tips all growing at once. I also constantly see people stress the importance of "good" or "a lot" of new root growth being present before you repot to s/h. So to me, I have been picturing that catt with tons of little root tips bursting out as what I want to see before reporting to s/h. Or at least 5+ roots.

Recently however, I have been advised by others that you really want to try and repot at the very first sign of new root growth. Many of my orchids have 1-3 new roots tips currently but because I have read Spring is when new growth starts, I have just considered these to be "straggler" roots. How many new roots should be growing for an orchid to be a prime candidate to transfer to s/h?

Thanks guy! Hopefully these don't seem too ridiculous! I just really want do set my orchids up for success, especially my newer to me Cattleyas!

[Ray]

Certainly your seedlings can handle semi-hydroponics, and even more certainly, the best time to move them into that culture method is when new roots have emerged from the base of a new growth. Usually, I wait until they are about 1/2" in length.

Be aware that the plants may very well lose the older, existing roots, but that's OK. If you have been keeping them evenly moist, the change won't be so drastic so they will last much longer.

[estación seca]

I would wait until it's a lot warmer. They'll be growing more strongly then. 72 F / 22C is not all that warm from the perspective of an orchid. There will be evaporative cooling of the roots in S/H, especially since your ambient relative humidity is probably low in winter.

Seedling Cattleyas do better without a temperature change, and the warmer you can keep them, the faster they will grow. Most people don't need to worry about temperature changes day to night for Cattleyas unless they have a growing area that doesn't change much at all through the day nor year. In Idaho I bet you get substantial changes through the year in how warm/cool you keep your home.

[emmajs243]

Thanks guys for the advice!

ES: really helpful to know that seedlings do best the warmer it is..the seedling heat mats do actually do a LOT in the way of keeping them warmer gen room temp. It was advertised the root zone would stay about 20 degrees warmer then room temp and although there were a lot of reviews confirming this I was expecting mor like ten degrees higher.

I did however set up a s/h set up, put it on the Heat mats then put a thin sheet protector cut out down that was smaller then then the pot so any air flow could escape up still and then placed my temp gauge on top of the cut out in an attempt to get an accurate read on what the root zone would stay at and it did stay about 12-15 degrees warmer then the room so more like 85-90 degrees which I found to be very impressive.

Oh! It also is very interesting to hear your thoughts on the temp change not being too necessary. At first I wasn't doing a temp change with them but then kept reading about how cattleyas do best with a temp change and how most orchids are found in higher elevation areas and actually enjoy temps below the human comfort level naturally so places like Carter and Holmes keep their greenhouses in the 70-80 range during the day and 55-65 at night. That is when I started deciding I guess I better give them some sort of temp change.

Ray: So glad to hear your opinion! About what size container do you use for seedlings in s/h? Smaller then a SOLO cup? I know that technically you can't really overpot in s/h so I will be the first to admit I am most likely over thinking this BUT! Looking at them in this tiny 2 &1/2" pot a solo cup just seems so big!

[estación seca]

I use 1 quart plastic food containers for anything that will fit into them, including seedlings. I buy them in sleeves of 25 at Smart & Final. I drill holes with a Dreml tool.

You need to be careful with newly moved seedlings. Their roots might not be long enough to reach the moist zone in the container, depending on your ambient humidity. In this case they would need daily watering/flushing until new roots grew deeply enough.

[Ray]

Part of the heating of a pot by a heat mat is by conduction. By placing a spacer between the mat and the pot, you are preventing that from happening, so the root zone will not be as warm as the air around it.

ES is right about the roots not doing well if they come into contact with dry LECA pellets, but there are several ways to prevent that: high ambient humidity, frequent watering (you cannot overwater in S/H), a temporary top cover to slow evaporation, or simply shorten the distance from the top of the reservoir to the top of the LECA by making the holes higher in the sidewall or using a shorter pot.