Quote:
Originally Posted by CourtneyT
I got the last cattleya from the same local nursery in the autumn about 2 years ago. It was blooming and healthy. But the same problem: root bound. I knew I should not repot it during blooming time but just cannot tolerant the roots exposed to Colorado's dry air. I repotted it in the similar potting mix in a plastic pot. I kind of remember watering it more often than I’m doing now. By Thanksgiving, it looked even worse. My husband's grandma is really good at the orchids. She said that I overwatered it.
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A good lesson. They grew in a warm, humid greenhouse. A typical home is not like this. Aerial roots on Cattleyas almost always die when moving from a greenhouse to a windowsill. This is not a problem for the plant, so long as the roots in the pot are healthy. When a Cattleya tries to grow aerial roots in a low humidity environment, they die quickly. Growers with low humidity need to accept the fact they will not have healthy aerial roots, and not worry about it. It doesn't hurt the plant at all if care is good.
In my experience moving Cattleyas from a windowsill to a humidified sunroom, Cattleyas can maintain healthy aerial roots if the humidity is regularly 50%-60% and not under 40%.
But the real problem was not repotting in bloom. It was what your mother-in-law said: overwatering. Remember, you damage roots when you repot. If there aren't new roots growing, the damaged roots can't absorb as much water as before, and the medium stays wet longer.
Sometimes we have to repot at the wrong time because of terrible medium, insect infestation or something else. The best thing to do in this situation is keep the plant as warm and humid as possible, and water less than normal. The increased humidity will compensate for less ability to take up water.
Quote:
Originally Posted by CourtneyT
She divided it to different positions for me and repotted them in bark and perlite in clay pots. After that, I tried to water less. The orchids tried to start new growth several times but all failed. Didn’t see much new roots growing and the old roots were dying. The pseudobulbs shriveled even more.
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Cattleyas in growth require a lot of water. Roberta discussed the ones that root at the end of the growing season. They rely on old roots to take in enough water to support the new spring growth. As she mentioned, it's a bad mistake to repot this kind in early spring, because the damaged roots can't support new growth, and the new growth dies.
Quote:
Originally Posted by CourtneyT
This time, I got this one and another root bound cattleya during Thanksgiving last year. Both plants were blooming.... The [aerial] roots around the pot were very healthy. We were gone for vacation for 3 weeks in December and my mother in law watered them for us once a week. When we got home, I noticed a lot of healthy roots outside of the pot were dying and the new blooms got smaller and some even failed to fully open. Since no more buds were going to bloom and I didn’t want to see all the aerial roots to die, I repotted both cattleyas.
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See above regarding aerial roots.
Quote:
Originally Posted by CourtneyT
The other one was not divided but I did remove most of the died roots buried in the pot.
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That's not a good idea.
Quote:
Originally Posted by CourtneyT
Maybe it didn't put too much effort to bloom, so the aerial roots were in good condition. It’s doing fine now. Even it’s not growing, all the pseudobulbs are still plumped. I had to divide this one because I cannot fit the whole thing in any single pot. After removing all the died roots, it seemed that I’d better divide it to three portions.
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That one had plump pseudobulbs because there were enough healthy roots to supply the plant. Later, you might have removed living roots you thought were dead. I don't remove any roots from Cattleyas unless they are black or dark brown, and slimy. After dividing the roots struggled to supply enough water.
There have been a lot of words spent on this thread; the takeaway messages are, don't repot unless you see new root growth starting, and don't remove roots unless you are positive they are dead. I rarely remove any roots when repotting my Cattleyas.