Bulbophyllums are giving me grief
 

Hi. I have about 40 orchids in 2 or 3 inch pots on our windowsills. Most are young cattleyas, but there are 4 bulbophyllums and although the cattleyas and oncidium types are in great health the bulbos all have problems.

There is a B. lasiochilum with a big pale patch. A B. lobbi gigantea with a chain of black spots, and a B. sikkimensis with a single black spot on a leaf tip. The photos below should be in that order. The 4th one is noid, multi-branched, and one new growing tip seems to be rotting off. It’s not really practical to photograph that fault.

Can anyone suggest the problem ?

Cultural notes: growing indoors in plastic pots, with pine bark medium. Watered frequently and weak fertiliser weekly. The cattleyas are dark green which suggests to me light levels are fairly low. Basically, the majority rules and they get treated like cattleyas. Minimum nighttime temp thru winter/early-spring on the windowsill was about 14 degrees Celsius (57farenheit) and max daytime temp was about 35 Celsius (95f) but that was only a couple of freak days. More normally about 25-28c. They got a brief winter rest through July and August. They’ll all go outside soon.

Thinking about it, I’m not a big fan of bulbos, so if there is any chance of them infecting my other plants then I’d rather just play safe and get rid of them. Can these issues spread to healthy cattleyas or oncids?

Cheers and thanks
Arron

Bulbos are water hogs that require very much more water than Cattleyas. Yours are displaying classic signs of insufficient water.

A many-awarded grower here in the US is Bill Thoms. Look him up. He writes he only has success when he grows in shallow baskets in sphagnum moss he completely soaks once or twice every single day. For many of the smaller ones he leaves the basket standing in a dish of water.

He writes he gave up on potting in bark, and mounting, years ago. He couldn't get the luxuriant growth he gets with sphagnum moss.

I realized that I truly under-watered Bulbos the other day. I gave a friend a small division of my B. lobbii about 2 years ago. Sunday I saw the monster size his had grown to inside the constant moisture and humidity in a university greenhouse. His plant was blooming like mad and ten times bigger than my plant!

Thanks for the replies. Now that I understand their requirements they don’t sound worth the hassle - off to orchid heaven they go.

Cheers
Arron

Arron, all you really need to do is switch medium to sphagnum moss and keep them a little better watered.

Perhaps, but due to other commitments I have limited time and don’t really want to expend it on plants that are outside the two families I am most interested in (cattleya and oncidium alliances) - at least not if my fairly generic culture is not going to work for them.

I am slowly coming to realise it’s probably better to stick to one alliance and do it well, rather then try to grow every orchid that crosses your path and never really master any.

The dendrobiums can go to. Same reason.

Cheers
Arron

I recently moved some that were mounted or in bark to a mixture of coconut husk chips and a little charcoal. The coconut chips hold water much better than the bark and I can water them more or less on the same schedule as my cattleyas. I've seen more root growth and several new bulbs have started.

Sounds like you're leaning toward getting rid of them, but just wanted to add to the thread for anybody else who might face the same issues.

Rothrock 42, Does that work as well as spag? Mine is in moss but, I hate the green algae, ugh. I'd love to try something else.

Probably not quite as good as sphagnum. But I think the coconut chips won't break down as quickly. And they hold a lot more water than bark.

Be sure to give the chips a good soaking with several changes of water before you use it. I found that it was quite 'salty' and bulbos wouldn't like that.

I've only been doing it for a few months, but it is very encouraging so far. Ask again next year!

I grow in the house. I keep the humidity pretty high for indoors and have a fair number of fans running 24/7. Depending on conditions ymmv.