Define cold and what kind of phal it is.

tj

Agree with TJ.

How cold? What are the night temps? What type of Phals?

Jane

If it is the type that needs the cool down period, I believe 2-3 weeks is the general rule.

Good luck,

Bob

Sometimes I forget that I have actual books to refer to, on which I relied heavily before the web. Rebecca Northen suggests that IF spikes seem reluctant form, a "few weeks" of 55F or even 50F should help. Jack Kramer states that temps for phals should never drop below 54F. Make of that what you will. Personally I've never found it necessary to "fall cool" phals for spiking. Not intentionally anyway. Also, species tend to be more demanding of this than modern complex hybrids and mericlones. Northen also cautions against over-lighting phals in the growing season but states that in the fall, increasing light to 1500-2000 fc also helps in spiking.

I let all my orchids get a couple of weeks of 50 degree nights before I close the greenhouse down at night and turn the heat on. This includes the heat mongers, my vandas. Everything blooms.

Thank you all for your comments. I am in zone 7 Northern VA. I do not have a greenhouse, so I cannot control the temp. I took out all my orchids (phalaenopsis) and kept them outdoors for about 10 days, but it got cold (35) and rainy, so I brought them all back indoors. I have never done that before, so we'll see what happens.

Please, when you keep them that cool for a few weeks, do you even water them? How will they not rot? And if you don't water, will the roots desiccate?

Hi, Mike, I agree with Jane. I also keep my orchids on the dry side. They seem to be much healthier. Jane, what a great idea to keep them on a rolling cart. I have too many to do that, and since I cannot just throw any plants away, I get all my friends' orchids, too.

Don't mistake lower temps for cold temps. Phalaenopis orchids come from habitats near the equator, which don't experience cold weather. What triggers spike production is the cooling down after the hot summer temperatures reach their peak, which can easily reach up into the triple digits. My phals begin spiking shortly after the hottest summer months have passed. None of them required any actual cold, just cooler weather.

To better explain what I mean, here's a link to a page that goes over this in much greater detail: Chilling Phalaenopis

I'm finding that the temperature on my home window sill (northwestern New Jersey) have dropped naturally this time of year, which seems to mimik what happens in natural habitat. In With normal house heating, my min-max thermometer reads around 70 on the windowsill at midday (no drafts) and a few degrees cooler at night. I also have a room that I close off at night, and simply open a window an inch or two. Dang! I get a good 55 degrees in there. But again, while living in New York City for decades I never went to any extra lengths to "cool off" phals, and they all bloomed without fail, including a species Phal schilleriana. Plants can adjust, and pick up on several clues that it is time to enter into a new phase (i.e., blooming or rooting or growing) besides temperature differential. Some plants are more forgiving in this respects than others. Cymbidiums, some but not all spring blooming cattleyas. With phals, especially if you're growing at a window with some natural light, I'd let them alone, give them good general care, and just see what they do (or don't do).

John, when I lived in Michigan, I grew my orchids on my windowsill, and they were showstoppers. Someone even wanted to feature them in The Detroit Free Press. However, I lost at least 75 of them when I moved to VA, where I now have a sun room. You'd think my orchids would be Fantastic. No so. It has taken almost 13 years for them to come back. I don't understand it, unless I'm accused of taking too good a care of them. Hopefully this year, I'll get more blooms.

Well, "they" say that when you change your growing area, you have to learn how to grow orchids all over again. 13 years does seem a bit hard. Have you noticed african violets are like that. If you find the magic window, they'll bloom their guts out for you. If not, forget it.

lol!

I think it is a day length AND temp differential issue. And I find that hybrids seem to be more influenced than species phals, especially as far as temp drops. When I grew indoors year round I mimicked the shorting day length outside in the fall for 2-3 months, by Christmas "I" was ready for more light to fight the dark days of winter so I changed the lights back to 16 hours on. I also cracked a window in my grow room for 3-4 weeks in the early fall to induce temp drops. Generally the room was 75-80 during the day and 70 or so at night, in fall it would be 70-75 during the day and 55-65 at night. Nowadays in west central Ohio, I let mother nature do this naturally as I grow outside from May-October, but I do have my lights set back to 14 hours for a few months, and back to 16 around Christmas.

Bob

I agree with everyone. I had Phals which would start spiking late August, others who needed to stay outside longer. My Dens did the same thing. I'd get spikes starting in August/Sept and would bring them in and out. Mainly for the additional sunlight they didn't get in the house.

Bob, I had a couple of catering plastic carts. Someone was throwing them out and I grabbed them. They were huge and had two trays. They were great because they were lightweight and had a rim around the trays. So I'd roll the orchids inside, leave them on the carts and roll them out the next day.

My friends made fun of me!

Anything for those blooms!!

Jane