Need help NOT rotting Catts, namely minis

[lotis146]

So, my Catts don't like me so much because I seem to be failing them. One minute I've got a bunch with several new growths and the next more than half of those new growths are rotting away. These are all minis and almost all different, most of whom spent the summer outside and often got rained on more than once a week. Now with me back at the watering helm I don't water more than once a week with some misting in between there and yet I've quite recently lost a lot of new pbulbs, some younger than others. I know they're not getting enough light and am in the works trying to reconfigure my set up, possibly including adding lights for them. Is that enough to cause them to rot...?

Most of my other Orchids - Oncids, Paphs, Phals, Zygos - would probably be happier (okay not probably) with MORE water especially more humidity now that we're indoors with the furnace on.

Thanks for your replies.

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[Leafmite]

After many years of growing Cattleyas, here is what I have learned:
1) Don't mist in the winter. Cattleyas do not need all that much humidity and if the water gets into the new growths, they rot.
2) lava rock or expanded clay pellets are the best mediums for Cattleyas if you live in a cooler climate.
3) Basket/net pots are the best pots if you live in a cooler climate
4) When watering, try not to get water in the new growths during the colder months.
5) Cattleyas seem to require a constant source of Calcium. When I get a new Cattleya, I put in eggshells with the medium and then add a soluble source of Calcium to my water
6) If the Cattleya has walkeriana or any of the smaller species that like to dry out very quickly, consider growing them in baskets or large lava rock
7) If growing in the windowsill in a cooler climate, spring is the best time to re-pot orchids. Orchids tend to grow more slowly with less light and adjusting to a new medium can be more difficult.
6) If you are using bark, the bark holds more water as it begins to decompose and, in cooler climates with less light, this can cause Cattleya roots to rot. That is why I no longer use bark.

I did switch to lights this year for the orchids and really love it. I have too many other plants that require the south-facing windows.

[AnonYMouse]

If you are growing them in the window sill, it may be too cold for them.

[silken]

I agree with much of what Leafmite has said. I learned from Leafmite about the calcium and feel it is producing healthier Catts for me. I do grow my Catts in medium bark in clear pots with good drainage holes and good moving air and have not had a problem with root rot. In winter the greenhouse is down to 55F at night so it's pretty cool. I just make sure to let them completely dry out before watering in winter. With the use of some seaweed and the clear pots my plants get very good roots so they actively take the moisture from the bark quickly, before rot can occur. And I always re-pot before the bark is breaking down. They usually need a larger pot before that anyways.

I think the key is good air at the roots and letting them get dry before watering. Also the calcium.

[ALToronto]

I agree with Leafmite and silken. The only thing I can add is that a calcium deficiency can look like black rot. If you're only watering once a week, especially with rain or RO water and using a regular fertilizer, you are very likely seeing a Ca deficiency.

[LovePhals]

I agree. I also got the calcium tidbit from Leafmite and I use that (thanks Leafmite!) and have all of mine in Lava Rock, for the most part. They do MUCH better than they did before and I am supplementing with lights. If I get water in a new growth I dry it out.

[lotis146]

WOW, thanks so much everybody! I feel hopeful.

Couple more questions though. How often, in cooler climates, do you water when using lava rock and or clay pebbles?

Admittedly I have been watering my Catts with less regard for water getting in growths than I do with say my Phals. And it's really great to know that misting them in the cooler weather is not the way to go. I know its got something to do with the change in conditions from Summer to Fall and outside to inside because a significant number of my little plants and of their new growths have rot issues. My Lc. 'Elfin Blue' - whose bloom pics I've shared - I noticed has an older & a younger pbulb that are yellowing and soft (rotting no doubt). This plant is in a basket and hanging in front of a now south window. I started misting it more because it has a lot of free flowing roots. I wouldn't be as worried with that one if it were just the older because it's lower on the plant and I had to add some moss to compensate for the plant "growing" away into the air.

Thanks everyone for the tips on Ca too. Do you just take eggshells from say your hard-boiled eggs, crush em up and add to pots? I'll look for some other sources too.

Your experience and advice has been gratefully accepted. (My chids will thank you for it.)

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[ALToronto]

The main reason I love lava rock is because I'm a compulsive overwaterer, and you simply cannot overwater in lava rock (unless it's sitting in water).

For calcium, I don't like eggshells because they provide only calcium. You need magnesium as well, so you can either dissolve a small amount of epsom salts in your water, or add crushed dolomite limestone to the lava rock - it contains both Ca and Mg.

[RJSquirrel]

I was never happy with lava rock and Ray scared me away from using it to be honest. Thanks Ray

I only lost 1 catt this year from rot and it was an older loddigessii that hade been suffering for some time and I tried but it was a run of the mill nothing special plant. When the stems starting turning black and the bulbs were falling over, its in the trash. That stuff is very contagious and can spread just from splashing water around. I know people tell you to cut the rot off and quarantine them . I throw them away. I'm not playing keep away games with them. DUNK!!!

To stop the rot you got to clear the rot out and start with a basic sterilization of the plants with fungicide. bactericide combo.(I use physan which is fancy soap). And the broken record 33 1/3 mix of dyna rok, orchiata bark, and charcoal all medium sized has helped me not rot the catts.

Good and better air flow goes a long way to stopping rot before it gets started. Just the air movement alone can keep rot off if your on the border of to rot or not to rot.

You have a small acceptable growing condition 'window' with most orchids to get results. You have to open it up some and expand their range by being creative with your approach to how you can convince them to be your friend and not your nemesis

[silken]

I just buy a Cal/Mag supplement in a bottle and add it to my water when I feed them. I use MSU fertilizer which has that in it but I feel it wasn't enough as I am seeing some improvement after adding the supplement for about 8 months now.