Cymbidium yellowing and has green splotches on leaves
 

Hi, I’m really new to growing orchids and I’ve been panicking about my new orchid in which i got a month ago from an orchid nursery.

When I brought back my orchid I noticed that there were spider mites and mealybugs on it. Then the next day I noticed that the medium, right next to my cymbidium had this white cobwebby stuff. So i looked up videos on YouTube for help and found videos that I needed to transplant my cymbidium which at the time had a full grown flower stalk but not yet blooming. To cut all the dead roots off and spray it with hydrogen peroxide and leave to settle for 15 minutes. For the mealybugs i was recommended to use garlic alcohol by a helpful YouTuber instead of neem oil which i had no isopropyl alcohol or no money to buy it, lol. So i just used neem oil instead.

I wanted to grow it indoors near the windows but then i noticed that some of my cymbidium leaves started to yellow from the tips and sides. I thought that it wasn’t getting enough light as my windows is facing a fence with cat net and my whole backyard is under a porch. So there was still enough light to penetrate through the netting and some transparent parts of the roof. Diffused lighting.

So i took it out from my bedroom and left it partially under the porch outside but also able to get sunlight. Currently it’s winter in Australia. I’m in WA and we have a subtropical climate. So it’s been cloudy sunny and rainy in the day. The cymbidium is also planted in Leca as the medium that it was in was very soil like and the roots were was infested with mites when i took the cymbidium out…

So it’s currently blossoming the flowers haven’t come out fully but it’s starting to and my cymbidium leaves and bulbs are yellow except for the flowering bulb and its leaves. I freaked out when i touched one of the yellowing leaves and with the slightest of touch it just instantly broke off.

Attachment 158883
Attachment 158884

I don’t know what these green splotches on a fully yellow leaf mean. I looked everywhere on google and couldn’t find anything about cymbidium with green splotches on yellow leaves. Two of the pseudobulbs are yellowing as well.

I honestly don’t know what to do, I would like it if i can get some help.

My first thought is: Did you tell the seller they have an issue?

Most Cymbs are not meant to be grown as house plants. They thrive better outside and they are huge plants when fully grown.
So, what I would do is to put them outside, in the rain to control mites, and for mealy bugs, with a systemic pesticide it's easy to get rid of them (but you need to repot it as mealies grown in the roots too).
About the looks of the leaves, Cymbs are the orchids that I know of that have the ugliest leaves from all of them.
About the leaves falling off...it seems that's an older pbulb so it's perfectly normal to shed older leaves.

Welcome! Yes to *most everything mentioned above; there are a few of the miniatures that can be successfully grown indoors under lights, but all of the standards & intermediates grow best either outdoors or benched in the greenhouse [or shadehouse]
If you are in WA, you might try checking out the culture notes put out by the Cymbidium Orchid Club of WA have a browse :)
To me, your plant doesn't look to be in that bad of shape; in autumn and winter, it's pretty common for older bulbs to shed the bottom few leaves--the plant is sequestering nutrients in the pseudobulb to use later; it pulls moisture and nutrients from the leaves, which discolor as a result [it's what happens seasonally in nature with many plants, part of the reason that leaves on trees shift color in the autumn in parts of the world]. With no chlorophyll or moisture in the pipeline, the leaves discolor and are shed from the bulb.
Typically Cymbidiums aren't repotted or potted on when they are in spike; doing so will usually cause the spike to either abort outright, or it will stall the spike--it will later elongate, but the buds typically will not mature to the flowering stage. If pests are potentially going to kill the plant, common practice is to remove the spike [ie not allow the plant to flower], as it takes substantial resources from the plant, which could otherwise be used to produce new vegetative growth & roots. They're generally tough plants, on par with Den. speciosum for survivability [provided you don't expose them to prolonged freezing temps]
Good luck & keep us posted :)

I did tell them and they didn't really care about it but on an unrelated note these people had a really run down old nursery and it was really dirty and they had a 4ft fish tank at the entrance and it was algae infested, really dirty water and there was a bunch of large fish in it that were attacking the other fishes and it was really sad to look at. I put in a complaint to the animal welfare people as well.

---------- Post added at 11:12 PM ---------- Previous post was at 10:55 PM ----------

Oh okay. I do have strong grow lamps, humidifiers and a large window/air-con to create an environment that could be of use to the cymbidium. As i usually grow edible plants indoors. Presently they have already been repotted and treated. They have been outside for a month in the day time as nights tend to get very cold so i bring them indoors at night. I'm not really keen on using non organic pesticides as i have animals and one of my animals/cats has pica and she explores outside and i'm worried that she may get poisoned if i did use a normal pesticide as she likes chewing on leaves and other things.

Okay, thank you for clearing that up.

How cold?

Cymbiums can tolerate night temperatures down to about -2 deg. C esepecially if it warms up during the day to 15 deg C or so Below 0 flowers can be damaged, but the plant would be fine even that cold. They also can tolerate summer high temperatures up around 40 deg C, with a little shading.

Everything that has been said above about losing old leaves is correct. Not a problem. I sometimes bring mine in to enjoy the flowers when in bloom, but otherwise these are outdoor plants. They need the varied temperatures that nature provides, and want high light. (I use 40% shade cloth over mine, because summer sun is intense... leaves are lime green not dark green, and they bloom like crazy in the winter)

Btw, many well meaning people online recommend hydrogen peroxide for plants but it’s definitely a “use at your own risk” product. Regular store bought H2O2 is an indiscriminate oxidizer so it will just as easily kill healthy plant cells along with pathogens, and it may cause more problems than it solves. It’s not a product that has scientific backing for use on plants.

Specialty horticultural H2O2 formulations are not at all the same as the stuff sold for first-aid (and it’s not even recommended for first aid anymore either!) so it’s not a case where you can sub one for the other.

Also a comment about the LECA medium... you may be challenged to keep it wet enough. Cyms need to stay damp. I use small bark, and water every two days in summer, 3 days in winter. So unlike many orchids, these do not want to dry out ever. During the growing season they are heavy feeders, I give them some time-release fertilizer in the spring to supplement my regular light fertilizing, which is not sufficient for the Cyms.

While Cyms can grow epiphytically, they pretty much grow more like terrestrials. Well-drained but water-retentive medium.

Don't disturb it now, but in the spring (when you see new growth) you may consider repotting into bark.