Room temperature in winter

[Dewie7]

Hello again! Another question:

I have a diverse group of orchids, a few cattleyas, a couple dens, 2 cymbidiums, a half-dozen phals, 2 neos, 4 oncidiums, and one miltoniopsis. I'm sort of a windowsill grower. Most are living together in an enclosed stone porch with southeast exposure. Some are in s/h, 2 are mounted. There's a ceiling fan on low that runs pretty much nonstop and I have a humidifier set in the 60% range. The porch is open to the house at all times. I leave the door ajar to hold humidity in.

My question is in regard to the temperature in this room. In the morning, it's currently in the low 60s. As winter sets in, that will go lower into the 50s. During winter days, I utilize a radiant heater that keeps the room in the low 70s. Is this acceptable for this variety of orchids? I don't THINK I have any real heat lovers, do I? I have heat mats under the phals and recent s/h converts. Will continuing to use the mats offset the cold nights? I could use the radiant heater at night at a lower temp, tho it is costly.

[estación seca]

You don't say which kinds of Dendrobium. Some prefer to stay warm, and some prefer to get quite cool. Do you know what kind you have?

The warmer you can keep Phals the better. The heat mat is a good idea. If you have a bright window available in a warmer spot in your home I would move them there, and not worry as much about humidity. Warm temperature is more important than high humidity for most hybrid Phals. 50s at night and low 70s in the day is pushing it. With those temperatures they should get little water - just enough to keep the leaves from shriveling.

If you have Dendrobium phalaenopsis hybrids you should keep them with the Phals. Den phals like to be warm and watered all year, with a little less in winter.

The Cattleyas, Cymbidiums, Miltoniopsis, Oncidium, Neofinetias will be fine. The Cattleyas and Neofinetias should not stay moist. Most people let them get dry and stay dry for a few days between watering in winter. The others should not go dry.

The Cymbidiums would be fine with much lower temperatures, if necessary. A lot of people reserve their heated spaces for other orchids and put the Cyms someplace where they get good light, but can be quite cool.

If you have Dendrobium nobile hybrids, those temperatures should be fine. They will tolerate even lower temperatures. These need quite cool winter night temperatures to set buds. Many people who can't keep them cool enough can't flower them.

If you have the space, consider putting some 32-gallon black plastic trash barrels full of water in there. Keep lids on them or you may have mosquitos. They cost $15 each here at Home Depot. The water will warm up during the day and keep the nights warmer as it releases the heat. If you can situate them so the sun hits them through the window, so much the better.

[Dollythehun]

I have a similar situation, with similar plants. I invested in an electric fireplace with a thermostat which I set at 62f. I have had no trouble and on sunny days I open the French doors into the house. Since this is living space/entry way, looks are important to me. You are only a hundred miles from me but, way colder (I think) as you have less benefit from the lake.

[Dewie7]

Thank you both!

I have a dendrobium nobile hybrid and a kingianum. I think I'll move the kingianum & phals to anther room.

Learning what elements are most important to each genus is interesting. Like phals are OK with less humidity but prefer a bit more warmth.

And Dolly, we're practically neighbors!

[Dollythehun]

Practically. Minus the politics 😉

[estación seca]

Leave the Den. kingianum in the cool room. It also needs cool winters to bloom, the cooler the better. Kingis grow well with Cymbidiums throughout the year.

Don't let it dry out for too long, but getting dry between waterings is fine. Cyms need to be at least somewhat moist all year.

And don't fertilize any of them in winter. If the Miltoniopsis and Oncidium begin making new growth, begin fertilizing. Some of the hybrids can grow all year, and they often like cool temperatures.

[Dewie7]

Thank you, ES. Will do.

So you don't recommend the practice of "fertilize weakly weekly?" Or not feeding in winter is because the room will be chilly and I should not encourage growth under this condition?

[estación seca]

Plants use fertilizer pretty much only when actively growing. Your Cyms, Miltoniopsis and Oncidiums might grow this winter, but the others likely won't. I would consider fertilizing those, but only if they're producing new growth.

Nobile type Dens are prevented from blooming by fertilizing much past late summer. If you go to Kawamoto Dendrobiums Hawaii you can read how to grow them successfully. If you've been fertilizing yours up to now it might not flower next year.

[Dewie7]

Thank you very much for the explanation.

[Ray]

Set the thermostat for the lowest temperature you want the plants to experience, and don't forget that those closest to the windows will still be cooler than those away from them.

Let the sun do any additional warming, and do not boost the daytime temperature above that minimum artificially. The rate at which chemical reactions occur within plants can be temperature controlled. If you warm the plants when it is a gray day, they will tend to be leggy and weak.