Heating during the day?

[Pinkcat]

Hello everyone,
I have a little polycarbonate greenhouse that I put my tropicals and higher light orchids into during the winter. I have managed to keep the temp above 50 during the evenings, but the daytime temps are not far from that.

I live in an area that is literally cloudy at least 7 months a year. The sun doesn't peek out at all which means my greenhouse gets no heat at all from the sunshine. It is averaging a low of 53 at night and a high of 63 during the day (if I am lucky). The average humidity is 88%. I am afraid that everything will just languish in these low temp,high humid conditions. Should I just give up and bring the orchids inside? Any ideas for raising the temp during the day without using the space heater?
I am getting really frustrated...grr...

[Ross]

Originally Posted by Pinkcat

Hello everyone,
I have a little polycarbonate greenhouse that I put my tropicals and higher light orchids into during the winter. I have managed to keep the temp above 50 during the evenings, but the daytime temps are not far from that.

I live in an area that is literally cloudy at least 7 months a year. The sun doesn't peek out at all which means my greenhouse gets no heat at all from the sunshine. It is averaging a low of 53 at night and a high of 63 during the day (if I am lucky). The average humidity is 88%. I am afraid that everything will just languish in these low temp,high humid conditions. Should I just give up and bring the orchids inside? Any ideas for raising the temp during the day without using the space heater?
I am getting really frustrated...grr...

It's been a few years since I lived in Oregon (Grants Pass) but I don't think you need to give up. True, there are some sun-loving or high-light-loving 'chids you might want to forgo, but why not go for those that are naturals in your area like Cymbidiums? I'll bet you can almost grow them in the ground in Portland . The space heater will only be necessary if you insist on growing warm type 'chids like Phals, etc. Stick with cool growers and you should be "good to go". Ask the Brits for their advice (Shakkai, etc.)

[Jeremy]

I think you should try to grow orchids with high intensity lights like metal halide. You get the benefit of bright light to grow high light orchids and you may also notice that the light generates enough heat to warm the greenhouse slightly higher.

Jeremy

[Ray]

If you're not going to add supplemental lighting, DO NOT artifically increase the temperature.

Vegetative growth is faster under warmer conditions, but if the light level is not commensurate, the cells become elongated, which results in soft, lanky growth that may not have the strength to hold itself up.

Add a fan so there's a fair amount of constant air movement in the greenhouse. Not a "hurricane", but enough so there's no stagnant air. That will convert the place from a good fungus incubator (especially after watering) into a pleasant, "buoyant" atmosphere, even at the cooler temperatures.

[Pinkcat]

Thanks for the replies everyone. I wish I could have mh lighting in there. Unfortunately, there is only an extension cord out there, so supplemental lighting isn't possible. It is actually pretty bright here, just not sunny. I wrapped the whole gh in plastic like a present today and removed the shade cloth. When the sun came out, I was able to get it up to 79.
I have a fan on in there now, it does a good job of stirring the air up. I think I will try adding another fan if I notice any problems starting.

One piece of advice I would give to anyone thinking about growing in a gh would be to have it up and running for awhile, then decide what plants to put in it. I did it the opposite way and built a gh to house the plants I already had. This results in me trying to meet their needs instead of going the easy route you described and picking plants that suit the gh. I guess I don't want things to ever be easy.

[Phantasm]

My greenhouse is in Seattle, so my conditions are quite similar to yours. When the weather changes in the fall, the shadecloth comes off and I start to watch the night time temperatures. When the greenhouse drops below 55F, the heater is cranked up to heat between 55-60F at night. The day temperature is still quite warm even on cloudy days, yesterday it was 66F on a rainy day, today with mixed sun and clouds it was 80F.

The temperature changes and differences in light will tell many of your plants to switch to a blooming cycle....cut down fertilizer and don't water when the temperatures get low.....below 50F. Even in the coldest sunny days in the winter it will be almost 70F in the greenhouse. Fortunately our weather is pretty mild compared to much of the country. Night is the time that will work your heat....

[Pinkcat]

Phantasm-how funny, I think you sent the rain down this way. It was partly cloudy yesterday and it got up to 85 in the greenhouse. Today is full clouds/rain and it is topping off at 68. I am excited about seeing what the temp changes will do to the plants now. It will be an interesting experience. Do you grow any vanda up there? How do they do for you?

[Phantasm]

Pinkcat,
My vandaceous plants are limited to a few V.coerulea hybrids, and several Ascocentrums....these all do well in my conditions. Warmer growing vandas are just not happy in my greenhouse. Hybrids derived from Neofinetia falcata also do well and can handle lower temperatures.