Old bark mix
 

Hello everyone!

I have a Cat. walkeriana that I've had for years and has NEVER flowered! It is quite big, about 12-15 bulbs, nice and healthy roots, puts out new growths all the time, but no blooms..

I don't think it's a light issue as its unshaded in a south facing window and the leaves get little purple spots on them which I've read is an indication that it's receiving a good amount of light. I have had great success with oncidiums in the same location.

I also have it on a day/night thermostat so I don't think it's anything to do with the diurnal range. It's usually about 15 degrees C at night and 25-30 in the day.
The only thing I can think it that the potting media (bark chips) is breaking down and producing a lot of nitrogen which is suppressing blooming and just causing he plant to keep putting out new growths. Does this happen?

I haven't repottednit in about 2 or 3 years, just because it seemed to be fine.. But now I'm thinking otherwise.

Any advice would be greatly appreciated!

Thanks.

Do you have the possibility to grow it outside at least part of the year? A lot of radiation is filtered through the windowpane and might be the useful part to get the plant to flower.
Sometimes though, some plants are very reluctant to flower.

On nice sunny days I sometimes do but not often. I've got a greenhouse now so might try it in there over summer once I've got it all set up. That's interesting about the radiation though, never heard of that before but it certainly could be a factor!

I might divide it soon.. It'd have about 6 or 7 mature p-bulbs each division. See what difference that makes next season.

If it is growing that robustly, I doubt that it's a light issue, and most windows only block some UV wavelengths, which are not part of the equation, in this case.

Bark is quite low in nitrogen content, so it's decomposition won't release at a rate that would stifle blooming. However, if it is "going south," that could stress the plant.

That leaves other parts of your culture as the potential culprit. Tell us details about your feeding and watering regimen.

Okay, I usually give all my plants a mist with rainwater once or twice a day and give them a good flush through the pot about twice a week, depending on how hot it's been. I'll usually fertilise with Orchid Focus Grow, mixed up to the bottles instructions, about every 2 weeks. Sometimes I'll use both the Grow and Bloom fertilisers together to get a more balanced supply of nutrients.

In the winter I just give them misting every couple of days and only give them a good flush through when they are bone dry.

Not knowing your temperature and humidity conditions I'm somewhat concerned by the watering. It seems often. You need to make sure the media completely dries out before watering again. Also, twice a month with full-strength fertilizer is a lot; I'd suggest cutting it to about 25% of the label directions and using it weekly. Finally, if the plant hasn't been repotted in several years it is probably due. However, I wouldn't divide it.

I only do water when the media is dry - if it's not, I leave it. The fertiliser is one specially formulated for orchids and I have just been sticking to their recommendations so far. It is already very weak compared to your usual everyday fertiliser, the Bloom one for example: NPK 2.2 – 1.2 – 2.1

Spring/summer days can get up to 30+ degrees C with nights of about 17-20.

I have a fan on constantly too.

Humidity usually sits between 40% - 60%

---------- Post added at 02:51 PM ---------- Previous post was at 02:50 PM ----------

Sorry I meant he GROW one.

Not BLOOM.

Here is a photo of the plant

C. walkeriana tends to prefer a cooler, drier, bright winter. So that while the temperature range during the day appears to be good, it may also be looking for a seasonal variation. It may be tricky to manage all of the winter requirements, but if you can keep it cooler and drier in winter, you might get it to bloom.

I do provide cooler and dryer in the winter but the only thing I struggle with is sunlight during winter. Pretty dull and cloudy here in the UK.

During winter I change the temp on the thermostat to 12 deg C during the night and 20 in the day.

Summer it's 15 of a night and 25 during the day. But most days it climbs to about 30+ when the sun is really out.