Wintering and dormancy with S-H/LECA culture

[amok]

Thank you for the quick response Ray. I am a newbie and I've put all my plants in SH. Went thru all the material at your site and a lot of your posts here. Tons of helpful information.

I just realized that my qustion in previous post was not clear. I was asking about phal. But you did provide the answer anyway. It boils down to how cold that specific type of plant can tolerate, SH or not. It just that with SH, the evaporative cooling will cool down the root zone a little more throughly compare to other growing method. Since I can't really control the room temperature too much at where I live, I guess heat mat might be the best answer... if I can find one.


PS. I use clear pot as the container for my plants, and I never thought I would find it so much fun to watch the root of the plants crawling all over the place... =)

[daddydoall]

Time for a follow up on my experiments with SH orchid culture (mostly Cats). I have used 3 methods.
1. LECA in plastic nursery pots in a shallow tray.
2. LECA in plastic containers with side holes (Rays method).
3. LECA in clay pots with a tray (individual or shared).
4. LECA in open mesh container with / with out reservoir.
All have benefited from bottom heat.
In a tray, water and fertilizer / systemic insectiside is simple to maintain and makes it easy to avoid wetting the leaves which is very important in not so warm GH during the cooler months. This method is more convenient for small pots-pony packs, but worked fine for larger 4" pots too. Metal trays work best since the bottom heat is transmitted and the water-solution warms up nicely. Plastic trays are cheaper (free) but do not transmit the bench heat, but do work ok. I am going to try to find stainless steel cooking sheets, as I am not sure the effects of iron or aluminum corrosion on Orchid health. Individual side hole (SH-SH) are also easy but need individual inspection and care with watering (I used a cup instead of a hose). This makes most sense for indoor SH culture. Making extra ventilation holes higher up the pot does hurt.

Now for clay pots; one can not over-emphasize the influence of evaporative cooling. Clay balls in clay pots evaporate very very quickly, even in cool weather. Even with bottom heat on the clay pots feel cool to touch. The result is cool medium and poor root growth or worse-rot. This is less an issue in non-SH culture since the medium is more retentive. I like clay pots because they are heavy and more attractive and don't tip. However, I am now transferring all the SH plants into plastic. I am also going to avoid clay for any warm loving orchids (most), except in larger sizes (6") where the lower surface area to volume ratio is lower reducing the evaporative cooling effect.
I have also tried LECA for dry growers with out bottom heat as a substitute medium (non-SH). It is working ok, but I suspect Lava would be better as it has less evaporative cooling effects.
Summary:
1. Do NOT use clay pot for SH, evaporative cooling effects are hard to overcome, especially in smaller pots. Leca in open mesh pots has a similar problem with too fast evaporation.
2. Plastic pots with or without extra side hole ventilation and with either a shared reservoir-tray, or in pot reservoir works fine. Smaller pots are easier to maintain in a tray.
3. Bottom heat is very very helpfull, especially in getting plants estabilished. Bottom heat transmits into indivual pots better, than with a tray.
4. LECA absent the SH-reservoir may work well for "dry-growers' but I have not determined if it offers any advantage over lava rock.

[Ray]

Originally Posted by daddydoall

1. Do NOT use clay pot for SH, evaporative cooling effects are hard to overcome, especially in smaller pots. Leca in open mesh pots has a similar problem with too fast evaporation.

That may be true for warmer-growing plants, but if your conditions are relatively warm and you want to grow cool-growing plants, that strategy is actually quite good.

Originally Posted by daddydoall

4. LECA absent the SH-reservoir may work well for "dry-growers' but I have not determined if it offers any advantage over lava rock.

Lots of growers in Florida use LECA and lava rock as their media of choice. My own experience is that lava rock builds up crud faster, and is harder to clean, but it's cheap, and if you don't mind repotting more frequently...

[daddydoall]

N California, and most of the USA is a lot cooler-dryer than Florida! I guess posters should always report their geography.

[daddydoall]

I think its time to post a follow up to my SH experiments with Cat and related,
I used three methods:
1. clay pots in a tray, it works but evaporative cooling is a big problem, still most the Cats did adopt and algae grows on outside of pot, the SH in clay pots have all been transferred to plastic.
2. Plastic pots with extra side holes in a water tray, works fine and a good way to adapt starters / seedlings which are more tolerant of the moist media till large enough to pot up. Algae grows in the trays, and larger pots are easier with #3.
3. Rays method clear pots (I like pint size and quart size) with side holes (I use a soldering iron to punch the holes). This is easy as pots can be move about at will and take their reservoir with them.

Adapting mature plants to SH can be a challenge since all the existing roots may rot / fail and the plant hangs on or dies till new roots grow. Keeping the pots warm with bottom heat is very helpful if plants are still adapting in cool weather. Having deeper containers and keeping the old roots near the top of the container helps as the top of the LECA is quite suitable for "normal" roots. In fact the new roots also look normal till they find and adapt to the reservoir. Once the roots adapt to the reservoir the plant really starts growing fast (faster than traditional media) particularly during the heat / intense light of summer.

So I am NOT going to transfer my Mature orchids which are healthy to SH as it took a lot of nurturing to get them there. When it is time to divide, I remove most roots from the older /discardable part and put it in SH (nothing to lose, and it works).

Most of my collection of 2-3" starter plants are now in pint or quart SH pots and doing well, after 1-2 seasons.

I am a believer now for Cats / cool temperature tolerant species. Evaporative cooling (sweating) is dramatic and some species will not adapt unless you have a warm growing area or use bottom heat.
Dave

[Houston]

All of my orchids are in s/h. Blc. Maikai and Cattleyas are flourishing after 3 Houston winters on porch. Lows down to 33 without evaporative cooling. Dendrobium Abberans old growth has survived but new growth going into dormancy died. All other cane dens I've tried to winter in sh have died due to rot. Guess I won't be growing them on my porch as I refuse to grow in anything but water and have 800 sq ft apartment with glass door as only window.

[Ray]

If you're getting root rot in plants that were already established and growing in S/H culture, you're simply allowing them to get too cold.

[Helene]

I measured temperature in the bottom of pots in s/h, and was a bit surprised that they were 5c (41f) colder than the rest (that means they were pretty cold in nighttime). So in my environment I need to make sure the night-drop tenperature isnt as high as the other plants.

So, as Ray says- make sure the water isnt too cold: cold and wet roots are not a good combination

Edit: measured inside the pot- not under the pot Just in case anyone didnt understand my english. Used the same thing I use to measure how my steak is doing in the oven😂

[Houston]

Ray i've since figured that out :-\ Still on the learning curve. However, I grow my vegetables in hydro, orchids in hydro and if I could swing it, my container plants in hydro :P In fact, i'm going to attempt an s/h hydrangea.

[daddydoall]

I have Aussie Dens in LECA and Lava rock-Dry out doors under an eave and they are doing fine in SF Bay Area including some nasty frosts. Keep the roots dry as possible (No SH) during winter and they should do ok.

I think SH is more suitable to warm GH than out doors where winters are colder.