Yellow spots on vanda leaves

[Mercurianmad]

Hi guys. I’ve potted up my Vandas in lava rock inside baskets with a coconut fiber nest around them. They dry out in two-three days. So why are there yellow spots on my orchid leaves? There is also a sticky spot in the base of the stem. When I got sticky spots on my phalaenopsis it was because of too much humidity. But since these dry out quickly I’m wondering what the problem is. There obviously is one and I’d like to resolve it for them.

I dug up their roots. They are not growing new roots but their roots are not squishy or rotting either. They look nicely moist because I watered them this morning. And I don’t water them until the roots are bone dry. I have a humidifier on them now but they’ve been without a humidifier for three days - the rh has been about 57 without the humidifier, on humidity trays. Ideas? Thank you.

[estación seca]

It's hard to say because they look indefinite. What are your temperatures? Perhaps too cool or too hot. Perhaps nutrient deficiency - nitrogen or magnesium. Vandas often are magnesium deficient. Chlorphyll needs magnesium, so magnesium-deficient plants can turn yellowish. It can take a very long time to replenish magnesium if that is the problem. Consider watering with a tablespoon / 15ml of Epsom salts per gallon / 3.78 liters of water, once a week. They are also heavy feeders. How are you fertilizing?

The transverse black spot looks like a sun or thermal burn. Fungus issues in your humidity range would be rare.

[Mercurianmad]

Yeah that black line is sunburn that came with it from the nursery. I’ll try the Epsom salts we have some from the garden. We also have Cal mag would that work? My temperatures are 74 maximum during the day and the plank it’s down to 62 at night. We’re going to be building a little area for it that would have a heater but that’s not gonna be done for several months

---------- Post added at 10:24 PM ---------- Previous post was at 10:11 PM ----------

I forgot to mention I use 1/4 tsp feed me orchid fertilizer per week, 1 T/ gallon quantum orchid probiotic once a month and 1T / gallon Kelpmax once a month for feeding.

[estación seca]

Vandas can survive temperatures like that but don't thrive. It might not grow much at all.

Magnesium deficiency shows up on Vandas as tiny dark red spots on the leaves in cool weather. Because you don't have that, but you have the yellowish patches, I suspect it's caused by the cool temperatures, and not magnesium deficiency. In your circumstances I wouldn't give extra magnesium. I use Epsom salts for magnesium because that contains more than does CalMag.

What's your relative humidity outside? Day/night temperatures? Any deer around that might eat your plants? If you can water once a day it might be happier outside where days are warmer.

I would also point out your house temperatures are great for intergeneric Oncidium hybrids. You should have no trouble growing and flowering them without any extra setup. You could also grow a lot of the miniature cloud forest orchids in large jars or terrariums, things like Pleurothallis.

It's also cooler in your house than Phalaenopsis like, so they wouldn't grow much, either.

[aliceinwl]

If you go with complex hybrid Phalaenopsis, they can definitely cope. My office has a similar temperature regime and mine do fantastic.

I have a Vanda ‘Santa Barbara Fizz’ that’s supposed to be tolerant of cooler temperatures. It developed something similar last fall. I left it outside anyway and it progressed to mesophyll collapse during the first cold rain. It seems happier as a house plant.

My temperatures are not too different from yours. I hang most of my Vandas bareroot in a window during the day and take them down to soak on the counter overnight. This also reduces their exposure to cooler nighttime temperatures. I’m sure people who keep them warmer than I do have more growth, but they’re still pretty fast growers for me.

[Mercurianmad]

Yeah we have a huge bug population outside. Entomologists come to our area to study the bug diversity, lol so I’m scared to put any plant outside. Nighttime temps outside are 53. Daytime temps are 102. Rh is 22. My house is set to 74 degrees but it just gets so darn cold
At night. Once the enclosure is built I am aiming to give them daytime temps of 85 and night temps of 75. But as I said, it’s several months out. Hopefully the Vandas will hang in there.

[estación seca]

Outside is too cold at night. You really are way up in the mountains.

[KennyS]

I've had the same with my Vanda. It hadn't had a fertilizer for a while. After the yellow discoloration was visible, I added fertilizer to the water again. After a few weeks, the color started to improve again. So in my view it is a nutritional deficiency.

[Mercurianmad]

Originally Posted by estación seca

Outside is too cold at night. You really are way up in the mountains.

Yeah we are! It’s tough growing conditions up here. We can grow Tomatos, roses and hardy herbs well enough outside but we have a hydroponic indoor garden for most of our veggies. The orchidarium is the next step for the orchids🙂 I’m just trying to keep them as comfy as I can until that’s built. I’m thinking I’ll put one full spectrum light in there and one high sodium light, for heat.

[estación seca]

I wouldn't buy a high-pressure sodium light. They're dangerously hot. A person touching one gets a 3rd degree burn instantly. Get LED lighting and a separate heater you can control with a thermostat.