A couple of questions...
 

Hello. I am a pretty new orchid grower/collector and am brand new to Orchidboard.
There are a couple of questions I have that I can't seem to find answers to through Google.
Everywhere lists eggshells and oyster shells as good natural calcium sources (and yes I know it is debatable whether or not added calcium is needed and which plants may or may not...) my question though is: if I wish to add calcium, can I use other seashells? (not just oyster) like say clam, sea snail, etc.

My next question is in regards to Phals and the the induction of flower spikes by lowering the temp. I keep all my orchids in a small greenhouse at about 24 degrees Celsius (day) and 15(ish) degrees (night). Would it induce blooming if I took them out of the greenhouse? It is significantly cooler in the rest of the house. About 10 degrees cooler in the day.

Thank you

Other types of shells from aquatic animals should be fine, though I can't really say all types will be comparable. I would think clams, oysters, mussels, scallops, and things like that would all be roughly equivalent. I'm not certain how useful it is, though I do use added calcium sources for some of my slippers just in case.

In years past I lived close enough to several lakes, rivers, and creeks that were littered with the shells of asian clams (invasive species in my area), so I'd collect those, boil the crap out of them to sanitize them, then crush them to bits (not dust) with a hammer after they dried. Seemed to work well. I also do the same with egg shells. When I know I'll be repotting, I keep the shells (in the fridge). Then once I have enough I boil them to remove protein remnants, dry them, then crush them into bits.

As for the Phals and temperatures, the answer is, it might work but no guarantees. There are some things I'd like you to consider beforehand. First, you should try to have a general idea of what kind of Phalaenopsis you have and also honestly assess whether the plant is mature and healthy enough to bloom. It's not the best strategy trying to force a Phalaenopsis to bloom before it is ready nor when it is out of season. So, try to get a general idea of what kind of Phalaenopsis you have.

Many of the big, standard, complex hybrids bloom predominantly from fall to early spring, so I'd recommend letting those types grow for at least a few more months before trying to force them. Even then, you may find that you don't have to do any forcing, basically when they're ready they'll bloom. Other types of Phalaenopsis are warm season bloomers that tend to bloom in the spring and summer months and those shouldn't need a temperature drop to force them to bloom. In fact, lower temperatures might cause them to delay blooming and/or stunt their growth a bit.

You could use cuttlefish bone. But I think any good fertilizer has enough calcium.

Thank You very much! I never considered cuttlefish bone.

Anyway, if you decide to use anything sea related wash it really well because of salt deposits.

With regard to messing with Phalaenopsis bloom time... commercial growers use temperature manipulation to "time" the blooming of their plants. There has been a lot of research in this area, because it's big money - the plant that blooms a week before Mother's Day is worth a lot more than one that blooms two weeks after. The manipulation is not going to force a non-blooming plant that doesn't have everything else that it needs correct, into flower. A hobby grower doesn't really care very much precisely when a plant blooms, just that it does so. To make THAT happen, getting everything else right (especially light and watering) is the important part.

As far as calcium supplementation goes, do you have a problem in the first place? What is your water composition? At my house there is plenty of calcium in the water (hard water) and the pH is about 7.8 - so shells or dolomite lime or any source of the mineral will be quite insoluble, hence useless. Like anything else, before you apply a treatment, find out whether you need it, and whether your intended treatment is going to do what you are trying to achieve.

Thank You all for your help! I've decided not to "trick" my Phals and instead let them go about their natural cycle. They are healthy now and I will continue to make sure they are all healthy.

My collection thus far:
A NOID mini Phalaenopsis (mounted), another NOID Phalaenopsis, 2 Epigeneium Nakaharae (one potted, one mounted) 2 Oncidium Twinkles (A Fragrance Fantasy, and a Red Fantasy) 2 Oncidium Euryclines (one mounted), a Maxillaria Variabilis (yellow), a Cattleya Mariae Piae, a Cattleya Intermedia var. Coerulea, 3 Paphiopedilum Maudiae Albas, and one Papiopedilum Maudiae Coloratum. 🙂

I don't presently know the mineral content of my water, but I will find out.

Thank you!

Your water provider should be able to give you an analysis. (In the US it's standard, can't speak for Canada) You can do the basics (Total Dissolved Solids and pH) with relatively inexpensive meters, but both make more sense and are more useful guides when combined with the detail from the analysis. Caution if you get TDS and pH meters... get the calibration solutions as well, to maintain accuracy.

Always find your baseline first!

From some of the info I've read, it looks like a calcium level about 40-75 ppm is typical for most plants. My water supply, for example, is at about 50, so I really don't need to add more.

Each species of plant has its own optimum level, but it is possible to overdo it too, slowing the growth. I think it takes an order of magnitude excess to become toxic.

Personally, I dislike stuff like oyster shell, as you have no idea how much calcium the plants are getting. But that's just me.

The calcium present in the oyster shells need to be crushed into a fine powder and made water soluble (just as Roberta mentioned) for it to make any kind of a difference or be reasonably bioavailable in a significant way for the plants, particularly with epiphytic orchids or lithophytic orchids. Any calcium that is weathered out of whole oyster shells are quite minimal and must be done over a long time and under the right chemical conditions. Sure, plants have mechanisms to chemically change the environment they grow in, but it has limitations, so you can't count on this for the oyster shells to be of good use.