Changing potting medium from volcanic rock to bark

[scout]

Hello,

I received two orchids as gifts and somehow have managed not to kill them yet . Recently, the dendrobium stopped blooming and I felt it needed to be repotted. The person who gave it to me upended the entire thing right before giving it to me, spilling plant and potting medium before stuffing it all back in to the pot; as a result, the plant was off balance and was always tipping over, also, when I watered it the potting medium (something black and very fine) drained out of the bottom. I went to the local nursery today and they sold me Humus brand orchid bark, and a 5 inch ceramic orchid pot, along with fertilizer.

New to orchids, when I took the plant out of it's old, 4 inch plastic container, and found the plant had been in what looked like volcanic rock, not bark, I got worried. I left the rock that was surrounded by roots alone, in fact, I didn't touch the roots at all. I set the plant (along with the rock in the root system) against one side of the new ceramic pot and then filled in with the pre-soaked bark.

My questions are: Is this plant going to be in trouble because I left the rocks in the root ball untouched; or because I changed from volcanic rock to bark? Also, do you think since it didn't need repotting due to its size the new pot is too big? If you see trouble ahead, when and what should I do to keep this great plant going strong.

Best,
S.

jmo i try not to repot dens unless it cant be avoided, they can sulk. i usually repot into the smallest size that can hold the plant and then stabilize the small pot in a larger one to prevent tipping. not disturbing the roots by leaving the lava rock will probably work out better for you. hope it does well

[jerrymeola]

I am usualy going the other way moving bark pots to hydroponic rocks. If the bark makes you fell better there is nothing wrong with it, but rock is becoming my main way of potting.

If the rock was red it is lava rock, if brown it was clay hydroponic rock, and if it was white it was pumice rock. Pumice is very commonly used in den mixtures, because dens do not like to be moved, the rock prevents the bark from becoming packed down when decomposing. Normally orchids potted in bark are changed every 2 years and this is not recommended for dens.

I would leave the plant as is for now. Dens are very easy growing plants, I have a neighbor who calls them weeds, they certainly grow like weeds. Keep a watch on it and be certain the bark around the outside of the pot is drying out. If you are in a clay pot the clay should draw the water out. Overpotting causes bark that is without roots growing in that section to stay overly wet and a breeding ground for rot and bacteria. Dens usually overcome this, but the plant will be spending all its time growing roots for the next six months and may miss blooming season this year. Failure to flower is the big problem with overpotting a den.

I have 10 inch high dens flowering now in one inch plug trays. I have 800 to pot this week. They have been in the trays two years. Fortunately dens like to be pot bound.

You did not mention whether or not the ceramic pot has drainage. This is very important, especially for dens. They like tight shoes, and I suspect it is because they like to get wet and then dry out quickly, and a pot filled with more roots than medium allows for this. Also, dens do not like a lot of nitrogen.

[scout]

Thank you all for your thorough and helpful responses. Let me ask you, do you think it would be a mistake then to immediately repot this plant in pumice? And, at the same time to put it back in a four inch pot? Also, Jerry do you put your dendrobiums in a rock mix that you make yourself, or buy -- and can you tell me what exactly the mix is that you use?

Thank you for your assistance.

Best,
S.