Seeking Advice - Improving My Flower Spikes
 

Hi all!

I'm noticing a consistent issue with my cattleyas. Although they seem healthy, growing and blooming consistently, they frequently seem to have mediocre flower spikes / stems. The flowers are sometimes crowded in the foliage, the flowers sharing a spike crowd one another, or both.

Here is some general information about how I'm growing them currently. If anyone sees anything here that could be improved, please share your thoughts. Thank you so much for your help!

LIGHT: I'm growing the cattleya collection under a full-spectrum Mars Hydro LED grow light. Based on testing done by a respected YouTuber, my light puts out an average of 854 mmols at full power at 12 inches above the plant canopy, and I'm running my light at roughly 35% power roughly 12 inches above the catts, so hopefully that's hitting roughly 300 mmols. I'm running the lights twelve hours per day.

TEMPERATURE / HUMIDITY: normal home temperatures, so probably a max of 80 degrees F and a low of 65 degrees F, but generally the temps that humans like. The humidity would vary a fair amount, I'm not currently monitoring it, and I'm not making any special effort to raise it.

WATER / FERTILIZER: I think I've dialed in my watering frequency pretty well, based on the health of the root systems that I've grown / generally plump pseudobulbs / few issues with root rot / no murdered plants thus far. Some plants are in bark mixes, some are in sphagnum moss. I used distilled water and my fertilizer is the K-lite formulation, which is an NPK 12-1-1 and should have the necessary micronutrients. I aim for 75ppm N when I make each gallon of solution. Once a month I flush the pots with tap water, and on the next watering after that I water with fertilizer plus Kelpak solution mixed according to the directions.

Please let me know your thoughts, thanks in advance!

The first thing that hit me was the light level.

For cattleya greenhouse culture, many recommend 300-500 µmol/m2/sec as the noonday peak under natural sunlight, which goes from zero to max to zero over the course of the day. The constant, artificial light equivalent would be about half that.

Also, you state that you feed at 75 ppm N, but how often?

Flower spike expansion is related to water transpiration through the plant and light intensity. Spikes with plenty of water available at all times, and low transpiration, expand better. With very high light spikes are far more compact. Ray pointed out you may be giving more light than necessary. You seem to be watering enough, so I would guess the issues are low humidity and high light.

I don’t grow catts. but the description of the spikes immediately suggested the light intensity was too high.

Are you growing species or hybrids? If you have hybrids, perhaps genetics is a factor, as a lot of hybrids seem to have the crowding issues that you described. But none of my species cattleyas has the problem you described. So maybe play around with light levels to see if that helps to correct the problem, or increase humidity levels during bud development and flower expansion.

Thanks so much everyone, this is all really helpful to me!

"For cattleya greenhouse culture, many recommend 300-500 µmol/m2/sec as the noonday peak under natural sunlight, which goes from zero to max to zero over the course of the day. The constant, artificial light equivalent would be about half that."

This is a distinction that never occurred to me, but makes perfect sense! I just thought of the 300 mmols as a target to hit with my lights, set it and forget it, but I can totally see why this would be excessive light across a 12 hour day.

"Also, you state that you feed at 75 ppm N, but how often?"

Currently I'm using the distilled water + K-lite solution at 75ppm N for every watering during a month, except the one time during the month when I'm trying to flush the plants with tap water. I have a small enough collection that I can be pretty attentive to the specific needs of each plant in terms of watering frequency, and for my catts it's between every 4 days and 6 days during the warm months.

"Flower spike expansion is related to water transpiration through the plant and light intensity. Spikes with plenty of water available at all times, and low transpiration, expand better. With very high light spikes are far more compact. Ray pointed out you may be giving more light than necessary. You seem to be watering enough, so I would guess the issues are low humidity and high light."

This makes sense, thank you! I don't think I'm willing to run yet another electric device to raise the humidity, so my catts might have to live with it, and hopefully they can perform if I make these adjustments.

---------- Post added at 01:34 PM ---------- Previous post was at 01:30 PM ----------

I grow hybrids, but as an example of what you're referring to, I have a hybrid catt which crosses a complex hybrid with harrisoniana, and that plant has a rather nice flower spike, decently tall and strong and with flowers that are fairly well spaced, at least to my amateur eye. Over time, I'd like to see which plants can achieve those kinds of results in my conditions, and maybe sell ones where I can't seem to avoid the crowding problem.

Your feeding rate seems reasonable.

Concerning the watering - how dry does the mix become in between? If it’s very dry, you might want to water more. Adding humidity may slow transpiration a slight bit, but does little in the way of giving the plants sufficient liquid.

In addition to what is mentioned above, most Cattleyas are not growing at the equator. Therefore, 12 hour day length prevents the seasonal sunlight change that many need to bloom well.