Dendrobium griffithianum

[estación seca]

What I meant is that 45%-65% is fine for most orchids. Your plants are mostly water stressed so the issue is not watering enough.

[NatalieS]

Humidity will vary during the day in these plants' natural environment, so personally I think your humidity is just fine.

However, humidity is not enough on it's own - it simply helps a plant that is designed to cling to a tree branch, rocks, leaf litter, twigs, etc. to not lose moisture too quickly. Orchids like your dendrobium will grow where there is a lot of rainfall in spring and summer, and they actively grow during this period so they can make the most of the available water. They will then usually have a dry winter rest (as you mentioned), with much less rain and humidity, and the plant therefore stops actively growing. Because you have a new growth, the plant is now actively growing, and you should increase your watering routine, as estación seca has suggested.

As already mentioned, some of your collection does look underwatered in the pic you shared, but some are potted in bark, some in sphagnum, and some mounted, so some of them are likely getting enough water while others aren't. I would say if the plant's leaves are very thin, papery, wrinkled, or lacking in rigidity on newer growths, or the newer growths or leaves are smaller than the previous growths or leaves, I would check how fast the medium is drying, and if it is drying fast, I'd increase your watering routine.

A plant that is slow to produce growths, or is producing smaller leaves and growths each season is usually struggling for resources, and that is usually water. I know because I've also had issues looking after my plants due to moving, stress, etc. Here's an example of a miltonia I've had for years - you can see the massive difference in size of the bulbs between last year and this year, as well as the wrinkled leaves, etc., all because of lack of watering.

[Liodoro]

Thank you both so much for your advice. I am keen to get this right. I will definitely water the mounted ones daily.

If you can bear another question:- I currently use water from my rain butt and warm it in a bain marie to make it room temp. It has a pH of 5.1 and I read that orchids do like a pH 5.5 - 6.0 in nature. Then I have soft tap water, pH 7.1 - 7.6. I do not have an RO unit. I could of course pour warm water over my orchids from my tap. But which method is best. I don't know the PPM in the waters.

And thank you for your photos. I realise that my first Coelogyne cristata was suffering from underwatering as the latest bulb is rather small. I'll try and get it back on track.

[Roberta]

Den griffithianum is not especially picky about water quality. Unless your your tap water is really bad, it should be just fine. Don't stress over that factor.

[Liodoro]

That's good to know. Thank you.