Laelia (Cattleya?) purpurata watering
 

Hi,

I have a question about watering needs of Laelias (Cattleya?).

I've recently found myself with a few Laelias (purpurata, and some related hybrids). All seem healthy, new roots, and actively growing... It's potted in a Cypress wood chip mix, indoors, under grow lights.

Since the p-bulbs began to shrivel, I tried increasing the watering from once a week to three times a week. When that did not help, I tried placing them in a saucer of water. This seems to have helped... although the P-bulbs have likely shriveled to a point of no return... All the new growths are happily making new leads and roots.

I've read that Laelia purpata loves to be watered during growth, but I'm a bit apprehensive of growing Catts soaking in a pool of water... Is it normal for these to require so much watering? Does anyone grow these constantly wet...?

I think having this species soaking wet all the time is a recipe for root rot. Do you have any pics? The plants might be dehydrated and need some extra moisture for a little while. Conversely, all the roots could have rotted out and that's the reason for the shriveled bulbs that won't fatten back up.

For orchids that have regular roots (eg. not roots that have made some adaptation to being fully submerged under water or in semi-hydroponic and/or hydroponic conditions) - constantly LIGHTLY moist roots with ADEQUATE air-movement among the media and roots is no problem.

Very wet dripping roots where the water around the roots doesn't move adequately within some amount of time - can be a problem.

What gets or kills the roots is if the water around the roots don't move enough - allowing oxygen level in the water in and around the roots to get too low. This can occur if air-movement through the media and pot and around the roots is inadequate.

So - to prevent too much resistance against air-movement through the pot, growers can try large enough pieces of media, or can try shallow enough pots, or whatever method works. There are certain kinds of plastic orchid pots where the bottom is basically plastic mesh - incredible drainage, which is often very nice. Generally - whatever pot or media style we use, there's often some compromises - eg. more airy big pieces media - faster drying, or shallow pot - maybe requiring frequent watering.

Now, even if we have appropriate size media, and good air movement, and good drainage pots - there are also other methods growers can use to cut down on issues with roots - such as watering method, watering schedule.

An important recommendation is to develop a reasonably accurate picture about the state of the roots and the media ----- at any particular time.

If your bulbs are all shrivelling - then first check the roots. The bulk of the roots may be grey in colour, and very wet, and soggy, and dead. This can happen if the roots and media are dripping wet all the time, due to a combination of the media type, media size, and not enough or big enough holes in the bottom of the pot, and even not enough air-movement in the medium and pot and around the roots.

For cattleya - I grow in very good drainage pots and scoria media, with good air-movement in the growing area. I water every day - using a weed-spray nozzle.

I water the orchids (even in their big pots) the same way. I water the media only - and .... for extra safety .... I can concentrate (focus) the water on the media CLOSE TO the SIDES (rim) of the pot. That's where I dump most of the water - along the outer regions toward the sides of the pot.

Much less water goes into the middle parts (central regions) of the pot.

In this way, the bulk of the roots around the middle regions of the pot still get adequate moisture (due to a slightly moist medium at the centre), or the roots toward the middle can still gather moisture from the air anyway when the medium toward the sides of the pot is wet.

It's not necessary to water every day. It just depends on the growing environment, and how fast the media dries. And cattleya can definitely handle having their roots (and media) being dry for a little while - which can also cut down on certain kinds of activity like bacterial/fungal/algae activity.

Also - if the cattleya orchids are growing outside in outdoor or semi-outdoor environments --- in some parts of the world, may have to keep an eye on the media and watch for things like snails or bush snails etc ..... in case they sneak in at some stage.

One more thing is ----- if you were watering only once a week, then it's also possible that your cattleya might not have been getting enough water. But - in any case - if you ever notice shrivelling bulbs --- ie. all of them shrivelling - then check the roots - just in case.

Finally - I've included some attached photos as examples of my watering of some of my catts. Even though I have very good drainage and air-movement, a nice rule-of-thumb is to avoid having roots and media dripping wet for long periods of time. I have no problem with directing most of the water into the outer portions of the scoria near the pot rim. Another approach is to water as usual - but just watch out for the mentioned condition (ie. roots very wet for long periods of time with inadequate aerated water movement around the roots and media - leading to oxygen starvation of roots).

I have a few (species and hybrids) and I grow them among my other cattleya hybrids with no special treatment. They grow well, probably the most vigorous of all my catts.

I grow in a shadehouse, in bark, in mesh pots, watering from overhead sprinklers 2 out of every three days in summer and weekly in winter.

I haven’t tried it, but I definitely would not grow them constantly wet - if by that you mean sitting in a saucer of water. If I get a plant that looks a bit dehydrated, I usually just mix in a few strands of sphagnum and wind a few across the top. That ups the moisture level for a while, then when I see they have recovered I remove the sphagnum where possible.

I don’t know exactly what cypress mix is, but if it is largely hardwood chips then it would hold very little moisture and would not be the medium I would choose for these plants.

Cheers
Arron

I agree with Arron. Definitely avoid putting in a saucer of water, which definitely blocks air-movement.

Jeff, I don't recall exactly where in the San Diego area you live, but now that nights are starting to warm up a bit, consider moving those C (L) purpuratas outside. That's where mine grow, and they do quite well. I have found them to be quite cold-tolerant (since yours have been inside, you do need to wait until nights are around 55 deg. F... next year they will be acclimated and then no worries, they're fine just a bit above freezing). Mine do better in baskets, wood even better than plastic, large bark so excellent drainage. If it gets hot and dry, just water more.

First of all, Laelia (Catt) Tenebrosa and purpurata share the same habitat.

Usually I water my tenebrosa at night in a more humid environment (HR = 60%). If you can give it these conditions (with night temp > low 60's) it will benefit from it. Cattleyas "drink" and "bread" mostly at night.
Putting it in a saucer with water might not be a good solution as it will also prevent air flow between the top and bottom medium layers (and obviously in between).

Sorry for the misspelling... Laelia purpurata.

I purchased these from Carter and Holmes, and it's potted in a "Cypress/Hardwood Blend and Spongerok". I've gotten a few Catts from them and they're doing fine indoors in the same medium.

I have a couple of other Cattleyas (species and hybrids) in BetterGro bark mix. I let them dry between waterings and definitely do not let them sit in water. They are doing fine indoors, under grow lights/windowsills. I've had them for a few years, got them to bloom most years, so I assume they are doing okay.

I'm struggling with the Laelia purpurata and Laelia pulcherrima. Roots of L. pulcherrima are declining this week - noticed root tips are becoming black today. Since new roots are emerging now, I've decided to repot them in plastic azalea pots (lots of holes, and have a few lying around) in bark medium.

It's getting mild in Mission Valley, but still some nights that dip into the 40s.

Thanks,

Purpurata does just fine in the 40's.

Jeff, I think that we're about done with cold nights. Even if it dips down occasionally, it's only for a few hours. For the purpuratas, I think that the benefits of growing in fresh air far outweigh the risks from an occasional few hours of chill, especially as the days grow longer and the sun brighter. Also, it's good to get them out before the sun gets more intense, so that they can acclimate.