Watering during heat wave?!?

[BarleyTwist]

Anyone here (esp in SoCal) feel like providing assistance and reassurance as I try to understand how best to care for my mounted orchids during this savage heat wave in SoCal?

I’m in Los Angeles, and my orchids are outside under retractable sliding shade canopies (not sure but think the canopies provide between 50%-70% shade). About 4.5 miles from the beach. Ambient humidity is around 50% these days. We’ve been experiencing daytime temps of 85*-101* and nighttime temps around 75*-77* for the past 10 days.

I’ve been watering all my outside mounted orchids every day, regardless of their individual regular watering requirements. Is this too much? I water by dunking them into a bucket of RO water. How long should the dunking last? I’ve also been using a manual mister on the hottest afternoons, but I’m pretty sure that water evaporates within seconds.

This is my first summer with these orchids outdoors and I’m unsure how best to handle the current heat. Any advice is most welcome — TIA!

[Roberta]

Daily watering for sure. Now, the down side of dunking (if you're using a single bucket) is the danger of sharing water - if one plant has a disease, you'll spread it. Really better to give bath with a hose. or pump sprayer. I have been watering in the morning early (sprinkler system, which I have rigged so that the plants that need RO get it) but I have a lot of plants... In the evening, I get out the hose and give everybody another bath. Actually, with the heat, evening watering is the most effective - dark and cooler (lately not by a while lot, alas) so the water has more time to be absorbed by the roots. Totally the opposite of what you will do as it cools off because you don't want to them to go to bed cold and wet. But right now, "cold" isn't going to happen, optimize the "wet".

And don't stress too much. As long as the plants get some shade, they'll be fine. Orchids are very well adapted to protecting themselves from desiccation - during the heat of the day, they close the stomata in the leaves to reduce water loss. And they typically have a hard cuticle on the top of the leaves which does the same thing. (That's why foliar feeding is pretty useless... they don't absorb water or nutrients through their leaves but rather through the roots only. ) I have LOTS of mounted orchids, and they have survived not only "monsoonal" heat waves like the current ones (they like the humidity even though we humans certainly don't) , but the hot dry Santa Ana winds that we still have to look forward to in a month or so. When it is hot/dry, overwatering is nearly impossible, definitely impossible for mounted plants.

[BarleyTwist]

Thank you!

I know that dunking in a communal bucket is risky. But it’s the easiest way for me to water with RO right now, so I’m taking the risk. All my plants come from the same (reputable) seller and are growing in the same location, so I tell myself that the cross-contamination risk is relatively small.

I’ve been watering in the afternoons, hoping the plants would take up the water well.

So will just hitting them all with the hose provide enough water? For how long — minutes? seconds? And if I decide to keep dunking, how many seconds/minutes would you dunk each plant?

I don’t have any way to get my RO water to them via hose, and the tap water from the hose is pretty warm these days.

Thank you Roberta.

[Roberta]

If they're all "Andy" plants (my guess), you should be OK with the dunking. A couple of minutes' dunk should be plenty - once the roots saturate, they're not going to take up any more. Hose with gentle spray for 5 minutes or so should have the same effect. If the sun has been hitting the hose, run the water on something else (like garden plants) until it isn't hot to the touch. (A hose sitting in the sun can produce water almost hot enough to scald) Warm (like ambient) not a problem. If you use the hose, wait until 5:30 or 6 PM - when the sun is low, to get the maximum benefit. In the morning, before 7 or 7:30 AM. When the Santa Anas blow and it's really hot, I will sometimes apply the hose in the afternoon... it's so dry that I figure they're getting some evaporative cooling with the hydration (They did not evolve in 5% humidity) . But the current weather pattern is humid. Orchids evolved in climates like that, so best to just ignore them through the heat of the day.

[BarleyTwist]

I can’t thank you enough, Roberta. (Not just for this info, but for all the helpful posts and photos you’ve shared here at orchidboard.com — would love to have a set up approximating yours some day!). Yes, these orchids are all from Andy’s, and i currently have less than 20, so I’m willing to risk the bucket dunking a while longer. Trying to keep things simple as much as I can. But I’m definitely feeling the restrictions imposed by the simplicity. Thank you so much for your help and encouragement.

[Roberta]

You're very welcome! An advantage where we both live... climate is very similar to that at Andy's so the outdoor-growing plants adjust without missing a beat.

[BarleyTwist]

Yep. I’m proceeding by trial and error, not sure how I’m doing so far, but not discouraged yet. Lots of root growth and a few new leaves; a Laelia anceps is working on 2 long flower spikes. Will try to dampen my enthusiasm for a while longer, until I see if I’m having any luck getting plants to bloom. Only one of my plants so far seems mysteriously “difficult” — a Laelia fidilensis that has dropped leaves and had several of its pseudobulbs turn brown. That said, I did order 3 more plants on Friday 😜

Thank you again, Roberta.

[Roberta]

Originally Posted by BarleyTwist

Yep. I’m proceeding by trial and error, not sure how I’m doing so far, but not discouraged yet. Lots of root growth and a few new leaves; a Laelia anceps is working on 2 long flower spikes. Will try to dampen my enthusiasm for a while longer, until I see if I’m having any luck getting plants to bloom. Only one of my plants so far seems mysteriously “difficult” — a Laelia fidilensis that has dropped leaves and had several of its pseudobulbs turn brown. That said, I did order 3 more plants on Friday 😜

Thank you again, Roberta.

If you REALLY want to indulge your addiction, consider making a trip to Andy's Open House in a couple of weeks. You'll see where he's growing things, and get a really good feel for how you can get close to the conditions the plants want. If you are in Los Angeles, it's only about an hour and a half to get there.

[BarleyTwist]

I’ve been to one of the open houses — think it was the spring open house this year. I don’t know if my self-restraint is sufficiently developed to resist the temptations right now, but I may well go!

[estación seca]

Given your environment, I suggest watering them well after dark during the heat wave. The evaporative cooling at night will help them tolerate hot days better. Your humidity isn't high enough to worry about fungus, plus they will dry quickly after a watering.

Consider getting a large (1-2 gallon / 3.7-7.4 liter) pump-pressure spray container from a hardware store for watering. You will waste far less RO water. These are commonly sold for pesticide or herbicide use.