NOID phals making crowns instead of spikes and a greenhouse heating question

[Silje]

First of all, I'm on the southern hemisphere so I'm going into autumn now.

I put up my small greenhouse in November 2012 and moved all my orchids there. Generally, they all loved it. I've still got some small issues with controlling watering and humidity (too much lime in the water and will need a filter), but the plants seem happy.

As most newbie orchid collectors, I got a bunch of NOID phals that have jumped into my shopping trolley on various occasions over the years.

Normally they would start to produce new spikes in a month or two when the temperature drops. But they've never been in a greenhouse before, and so...a couple of months ago, they started making spikes. i thought. As the 'spikes' were growing, several of them turned out to be basal keikis or secondary crowns. The plants are happy. There is no crown rot or root problems. Both crowns are making new leaves and the plants spread out and are becoming pretty big. I've had to repot a couple into larger pots. This has never happened before. My phals have only had one crown, and that's it. Anybody that knows what can be the cause of this? I've been considering temperatures, and I've got to admit it has been hot in the greenhouse now and then, but rarely (or not at all) over 40 C, and then only for short periods of time. I'm puzzled...and I'm also curious as to whether this is it this year...am I getting crowns instead of spikes or will they also flower?

Second question, also related to the greenhouse. I don't have a heating system in the greenhouse at the moment (it's a small greenhouse 3x2,5m), but I will have to make a plan for the winter. I'm considering a small electric fan or something like that. I'm not planning to invest in something very fancy and expensive, but I'd like to hear what you guys are doing.

We normally have some frost nights during the winter. Typically only in the early morning hours. My plan is to keep the greenhouse at a minimum of 3-5 degrees Celsius and make sure it's frost free. As I understand it, many orchids go dormant when it's getting cold and they should stay on the dry side in the winter, but are there types that will die if the temperature drops below five degrees Celsius (but not down to minus)?

I've got a combination of NOID phals, catts, dendrobiums (phal, callista and some others), vandas, aerangis and maxillarias.

If need be I'll just have to take the plants inside for the night, but I'd like to hear your experiences on this.

And my Angraecum Magdalenae is spiking! Yey!