How to provide humidity outside?
 

I just bought one of Seattle orchids' Dendrobium spectabile and as I would love to allow it to grow huge, I would love to keep it outside, but are summers are dry. Is there a practical way to grow outside other than a greenhouse?

I think your choices are a green house or similar enclosure to make your habitat suite the orchids or buy orchid species that can tolerate your environmental conditions “as is”. That said, maybe you could rig something with shade cloth and misters on a timer?

You don't say where you are in the U.S. Do you know what the humidity is like in your location? My dendrobiums usually summer outside, and the daytime RH drops to the low 30s often, but because I live near the water it increases greatly at night, up into the 80s and 90s.

IngieBee, I think you said you were in the San Fernando Valley (inland southern California) If so, humidity is the least of your problems with this species. (That can be solved with copious watering) I think that it won't be happy outside in winter at all - I doubt that it will tolerate night temperatures much below 55 deg F. High 40's F for a few hours maybe, but you go down a lot lower than that.

If you want to grow a big Dendrobium outside, consider Den. speciosum. That one won't mind the chilly winters, and is also fine with hot summers as long as it's protected from direct sun (leaves can toast without a little shading, learned the hard way). Also Laelia anceps and relatives.

I'm so sorry @fishmom! I haven't taken care of finding and setting my location, ugh... Hard to find on the phone, but i'll give it a try after this! I'm in the San Fernando Valley in North Los Angeles zone 9b I think 😝. Humidity gets to the single digits sometimes, but mostly around 20 or so? I have my kid's old swingset in the back and am thinking of throwing a sheet of plastic over it for the summer to get it to grow nicely. One face would get sun, the rest is/ would be in shade.

Ooh, Roberta, I'll look into it, I think it would be awesome to find orchids I could actually grow open and free outside! My sister has huge pots of cymbidiums that are 20 years old and always outside, so I got one which is doing fine in this cold so far :) if you have other ideas, I'd love to hear them! I planned on bringing the pot into the house for winter as I realized it would get too cold 👍

Don't worry about the Cym in the cold... it is fine at least down to 29 deg F. L. anceps likewise, and Den. speciosum and its relatives and hybrids as well. Take a look at my website Roberta's Orchids to see what I grow outside. My climate is a little milder than yours - not nearly as hot in summer and not quite as cold in winter, but pretty close. So you won't be able to get away with some of what I can, but still there is a LOT that you can grow outside. To quote a friend who is a superb outdoor grower (coastal, but temps still can range from 32 deg. F to 113 deg F, just not as often as at your house) - subtract some sunlight and add water.

:bowingWe'll, I am concerned about heat and dryness. But there are some plants I really like, and want to do well, especially the Dendrobium spectabile I just bought. I don't think blurple lights are going to do it justice. Probably my cattleyas either, so I've decided to buy a cheap greenhouse for now to be able to provide humidity and I think that will do just fine for now :).

Thank you so much Roberta and everyone for your thoughts, and I will go check out your post :)

I think the only way you're likely to do anything about raising humidity outdoors is to have a constantly- running swamp cooler blowing directly at the plants.

Nature "hates" a gradient and tries to equalize everything. Evaporation from a tray or wet ground around the plants will dissipate SO rapidly, the plants will never detect an increase.

The same will be true with a swamp cooler's output, but by directing it to the plants, the blast of moistened air will be mechanically "forced" around the plants before there is time for that to happen.