Catasetum new growth issues

[Maxx]

Hi Everybody,

I am relatively new the Catasetum alliance, with only 3 of them acquired in course of last year (a Fredclarkeara After Dark 'SVO Black Pearl' FCC/AOS; a Monnierara Millennium Magic 'Witchcraft' FCC/AOS, and last but not least a Cycnodes Taiwan Gold 'Orange'). Out of the three only the Fredclarkeara flowered.

After the end of their dormancy, when the first little nubbins of the new growth appeared, I repotted them all according to the PET method (1/3 layer packing peanuts in the reservoir, 1/3 layer medium orchiata bak in the middle, and 1/3 pure sphagnum moss tightly packed on the top) without watering them, and here is what happened:

Cycnodes Taiwan Gold 'Orange' (Pics): This one took rapidly off initially with thick new growth and roots, but after I started watering (when the new growth was about 15 cm in height and several roots have penetrated the medium) some of the roots began to turn black and mushy, and eventually died-off.
When I noticed this, I replaced the top layer pure sphagnum with a sphagnum / orchiata bark mix on all three plants, and added several holes for additional aeration.
Fortunately, some of the roots survived and branched extensively eventually reaching the water reservoir at the bottom of the container. So I guess this one will survive and hopefully bloom for me, although I still see some roots turning black.

Fredclarkeara After Dark (pics): This one started relatively fast to grow a new shoot after it has flowered, but it was very flimsy, the roots very thin compared to the cycnodes, and eventually the new growthy has become soft and mushy and died.
After the first growth died, a second growth started to grow, but this one seems also very thin and weak with small roots, so I am pretty concerned whether, it will make it. Any idea when I should start watering?

Monnierara Millennium Magic (Pics): This one started producing some nice thick roots, but in overall the new growth has not grown too much. Also some of the root ends seem to have dried-off for some reason. Should I fill up the pot with sphagnum to be at the level of the new growth, and begin watering?

Growing conditions: South-eastern facing windowsill, with plenty of direct sunlight from morning to about 2:00 pm, temperature: ca. 22-24 C, humidity is around 40-50% with humidifier).

Sorry for the long text, but I am really curious what I am doing wrong, as I purchased now a bunch of new flowering size catasetums which have all about 10-15 cm of new growth in small nursery size soft plastic pots packed with pure sphagnum, and I do not now whether I should try to repot them (and if yea, in what? PET method, pure sphagnum, small orchiata bark?

Thanks for any help in advance!

[SouthPark]

Hi there maxxx ..... some online sources reckon that recommended growing daytime temperature range from 27 degree C upward. Must be a limit of course ..... so maybe up to 37 degree C max.

If too cool, or relatively cool, then maybe cold and wet can lead to issues.

Even the media and the roots temperature need to be considered ..... cold and wet roots could create issues for the roots and plant too.

[Maxx]

Originally Posted by SouthPark

Hi there maxxx ..... some online sources reckon that recommended growing daytime temperature range from 27 degree C upward. Must be a limit of course ..... so maybe up to 37 degree C max.

Thanks! Unfortunately the temperature is the only thing I really cannot do much about currently, due to my climate here in Hungary, with now in spring max temperatures of 25-26 C outside on sunny days, but going as low as 10 C at nighttime.

I hope I can put them in my mothers garden (together with my Vandas and Cattleyas) once the nighttime temperature does not fall below 18 C, but this will take another month or so unfortunately

[SouthPark]

Most welcome Max. One possibly workable option might be to have a heat mat. Even if the bulb temperature is cooler ....... it may be that keeping the media and root temperature warm enough could sort out the root rot problems. What might be going on is ----- roots not surviving due too possibly too cold and wet (the roots that is). But having warmer roots could improve the situation.

[Clawhammer]

Likely going much lower than 22 on the windowsill if the temps overnight outside are going to 10.

How about getting a seedling heating pad?

[Maxx]

If really the heat is the only problem, I will definitely get an electric heating mat. Is there any difference of seedling heating pads and those used in reptile terrariums? Is there anything what I need to look for if buying one?

[Roberta]

I would be inclined to repot these earlier - before you see growth. Often, they'll start root production well before you see signs of action. (In nature, they do that to anticipate the rainy season, so that when the rains come they can immediately take advantage)

Also, when did you actually start watering? If right after repotting it was too soon. The hardest part of growing these is to resist the urge to water when you see green. You need that new growth to be well developed, and the new roots well established before giving any water. (Seems cruel, but that's what they need) I don't think that your house temperatures are all that much of a problem. Mine go outside once night temperatures get up to about 12 deg C (55 deg F)

[Maxx]

Originally Posted by Roberta

Also, when did you actually start watering? If right after repotting it was too soon.

Thanks Roberta! i did not start watering until the new growth on the Taiwan Gold was at least about 15 cm and the roots have penetrates the medium. I do not water the other two yet, just give an ocassional very light spray of fine mist bi-weekly. I am pretty concerned as I see that some of the monnierras roots developed pretty well but now stopped growing when they reached the medium (the root tips seem to dried-off).

[Roberta]

Hmmm... need the advice of the real expert on this... who also developed the PET method and uses it extensively, isurus79.

[SouthPark]

Originally Posted by Maxx

Is there any difference of seedling heating pads and those used in reptile terrariums? Is there anything what I need to look for if buying one?

maxx ----- my growing area is in the tropics, so I haven't used heating mats before. But the concept is really about a heating mechanism that has enough power to maintain a suitable temperature within the pot (and media) ------ so that the roots aren't too cold --- but at the same time not too hot ---- so reliable temperature control will be important.

Also - even for the 'PET bottle' method ----- if the water is relatively cold, then the growing processes in the roots (cells) could be impacted by the relatively low temperature, where the roots die. And the rotting could simply be due to what follows when roots don't make it as a result of being too cold.