Watering during heat wave?!?
 

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!

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.

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.

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.

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.

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.

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.

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!

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.

Pump sprayer works well... until I got my fancy power sprayer, I used it for fertilizing.

This last week (and it's going to extend probably until next weekend) we have been getting quite a bit of humidity with the heat. Very unpleasant for people, not so bad for orchids. Hot muggy nights too. (Coastal southern California with overnight lows of 76-77 deg F is NOT normal) Ick. But after a week of this already, I haven't seen any sign of heat stress on the plants (mounted or otherwise) with the bit of extra watering that I'm doing. Orchids are a lot tougher than I am... I do hate to imagine what my electric bill is going to look like with the extra hours of A/C.

Estación seca, is there a particular make or model of sprayer that works well? How long can such sprayers spray on a single water filling? Not sure how much less RO water it would waste than my current dunking approach, but I’m interested in checking out the sprayer method. Thanks very much!

---------- Post added at 06:16 PM ---------- Previous post was at 05:46 PM ----------

Roberta, what is the fancy power sprayer, in brief? I imagine it would be overkill for me, but I’m curious …

I got this one
Amazon.com
6.5 gallons, on a cart, with a battery and a long hose. But I have a big yard to cover ... I extend about 75 ft of that hose in two directions with the sprayer in the middle, find that I don't have to move it. And fill it twice. When I carried the 2 gallon pump sprayer around the yard, I had to refill it 8 or 9 times, and I'm getting too old to schlep that much weight around . For 20 plants, definitely overkill for my big yard... it has turned out to be a lifesaver.

If you want to start with something simple, this might work.

Needs to be carried, but isn't that heavy. The hose isn't that long so you need to hold it up in the air to reach some hanging plants. These also come in 1- and 3-gallon sizes. If using for fertilizer I recommend mixing in a bucket, then filtering through a coffee filter into the sprayer.

If you only have 20 plants, the gallon size should be enough. But you're not going to have 20 plants for long. :rofl:

Thank you — I’ll check them out. And I suspect you may be right about the number of plants multiplying!

That is the exact type of sprayer that I used for my fertilizing. And works very well for a small collection or one in a small area. I have one (maybe not that exact brand, but same item) that I use for my indoor watering. 2 gallons of water weights 8 pounds, so with the sprayer itself, about 9 pounds. (It only got heavy when I was carrying that much all over my large yard for several hours...if this old lady can carry one of these, anybody can :biggrin:)

I have a similar one in my garage — .75 gal I think. It’s a pain only because you have to pump it pretty often. I’m thinking the dunking might be better than pumping enough to water each plant for multiple minutes. But maybe I’m not thinking about this from the right angle …

When I water with the pump sprayer, I don't do it for all that long... potted plants, just until the water runs out. Mounted ones, sphag is damp and roots are green. The bigger tank will spray for longer than the little one (more headspace holds more air), but you still get your arm exercise. Dunking works for you, might as well stay with it for now. As your collection gets bigger ( resistance is futile :biggrin:) you'll be looking for other strategies.

One of the things to start to investigate... water quality. Get your water report, find out the Total Dissolved Solids level. We already know that the primary contributors to that measure are calcium and magnesium carbonates. (Classic southern California hard water) Some of those plants really do need RO, others may be fine with tap water (from a hose) Andy uses RO exclusively but the water in the San Diego area is much worse than Los Angeles and most surrounding cities. (Still not great, but not the liquid rocks that he has to deal with) But as the collection grows, you'll be looking for ways to keep everybody happy without working too hard yourself. So knowledge is power.

Wise words, Roberta. Right now it seems easiest to keep using RO water for dunking a each plant, but I suspect this might not always be the case. 😁 I looked at muni water quality reports a while back — they didn’t look exceedingly bad here, but far enough from “perfect” quality to motivate me to get a simple portable RO kit from Ray. That kit is working well and it’s easy enough to make the RO water to meet my current needs, so I’ll carry on as I am for a while longer at least.

I might think about adjusting my fertilizer timing though. Because I figure that orchids in the wild mostly get a steady stream of “naturally fertilized” with each shower, rather than mostly non-fertilized showers interspersed with occasional “nutrient plus” showers, I’ve been opting to feed 1/8 doses of fertilizer with each dunking. I have no idea whether that thinking holds any water, though (see what I did there?!), and maybe I should apply fertilizers less frequently at higher doses …

Actually, fertilizing lightly at each watering is great. That's indeed what orchids get in the wild. I can't do it... would need to incorporate the fertilizer in the sprinkler water (large investment) so I give a bit more less often. But what you're doing is perfect. Don't change it as long as you can manage it!

Well that’s reassuring! Thanks for that!