Excellent question. It really depends on the genus and species/hybrid though. Oncidinae and cattleya alliance plants typically produce new growths each season, and inflorescences only emerge on these new growths. However, a big plant can produce multiple new growths each season, and so you get multiple spikes. A well grown cattleya can produce 2 and sometimes 3 new pbulbs from an old pbulb each season (depending on the heritage of the plant of course). Also, oncidinae can produce 2-3 spikes per new pseudobulb.

There are other sympodials, namely dendrobiums, however, which will produce inflorescenses on older pbulbs (or in dendros, the typical term is 'cane'). In fact, some dendrobiums ONLY flower on old canes. This can occur multiple times, with old canes reblooming for many seasons.

Thanks Calvin. That's a great piece of information to know about multiple pseudobulbs in a year. Just out of curiosity, will these multiple new rhizome/pseudobulbs grow one after another in a line or do they ever branch? Now, when you say a big plant, what do you mean? I thought that every year or two you re-pot your orchid and remove the back couple of rhizome segments, and so the plant would stay basically the same size. Or do you remove fewer back bulbs then it grew forward and so are re-potting it into a bigger pot each time? Or, do you decide how big you want your orchid to be and trim it down to that each time you re-pot it? (or something else I haven't thought of!!)
Oh, by the way, I'm looking more at the cattleya alliance, if that makes any difference.
Thanks for taking the time to clarify all this for me. I just like to have a good grasp of things before I plunge in!

Each pseudobulb has several dormant 'eyes', which are located at the base of the pbulb. These eyes have the ability to start growing into a new pbulb. If plants are well grown, certain species will sprout multiple eyes at once and you can get multiple new pbulbs. I have learned of a technique where you can induce this to happen by cutting through the rhizome in between pseudobulbs, in order to trick the plant into thinking that it needs to sprout another eye from a dormant backbulb. By doing this at various segments, you are effectively 'dividing' your plant without unpotting it, and you can get multiple growing leads started. However, I believe this is only done with large plants with many pseudobulbs.

Repotting regularly is important for us space-challenged growers, as well as for the sake of the medium, which can rot over a few years if organic (ie sphagnum). However, plants growing on mounts, or in a loose inorganic media or basket can be allowed to grow for a very long time without repotting, and eventually you can get massive specimen plants with dozens of pseudobulbs. With these, sometimes the old medium just rots away and you have masses and masses of roots that act almost as their own medium, trapping water and nutrients. It's a pretty amazing sight to see!

These are great questions - I'm also always fascinated by the growth habits of plants; it's almost as fun watching them do their thing as getting the blooms themselves

If you don't want to keep moving up in pot size, you can divide the plant. The minimum is three bulbs to a division, and five or more is better. A three bulb division may be slow to bloom, whereas a five or more bulb division can bloom in the next blooming season. Anything less than three bulbs can take years to bloom.

Calvin, this IS very fascinating. Now the way I understand it there's a rhizome and it has a pseudobulb at the end (the leaves grow from the top of the pbulb), then there's a bit more rhizome and another pbulb. So when you speak of eyes at the base of the pbulb that can grow into new pbulbs, they will grow a new piece of rhizome and then the pbulb on that, right? And as long as it can grow straight ahead, most of those eyes will remain dormant?
This trick you speak of sounds really interesting! I assume a backbulb is an old psuedobulb? So cutting through the rhizome creates a similar effect to pruning any other plant. You have removed the end bud so the side buds take over to continue growing, just here the cut-off forward part is rooted so it keeps growing too. This is really amazing, but it makes a lot of sense! Now, when you cut through the rhizome and do not re-pot, the junction between what is now two different plants is still almost touching, right? And then the one towards the back is going to branch out around the front one. This certainly does sound like a big plant and a lot of room! But it's great information to have in the back of your mind so you can draw on it if you ever can!
What sorts of things are used as inorganic material? Are there drawbacks to using them to pot your orchids, or since it's just to stabilize the plant and hold a small amount of moister and nutrients, does it really not matter what it is?
Thank you so much for sharing you experience and insight with me. I really appreciate your willing to make things clear for me.

P.S. If all my questions are getting to be obnoxious just tell me to go buy one and see for myself!! ( :

What you grow your orchids in really doesn't matter, but finding the right fit with your conditions is the key. Essentially, balancing moisture retention with your watering habits, relative humidity, as well as the plant's preferences. Inorganic media can range from pieces of clay pottery, to lava rock, gravel, rock wool, charcoal etc...You're right - it's main purpose is to hold moisture and some nutrients. Of course, some orchids like the ones that typically are found growing in dirt (yes there are some that grow in soil!) would find it too dry. I grow a lot of things on the windowsill in my centrally heated house, so a purely inorganic media is too dry for me (I'm also a lazy waterer!) unless I use a technique like Semi-hydroponics (your inorganic media sits in a permanent pool of water, which gets slowly wicked up the pot...google it for me info).

Generally the order of water retention goes by:

Sphagnum > coconut husk > bark > perlite/other inorganics

Your questions are intuitive which is good! Now go and buy yourself an orchid and experiment!

Thanks a lot Calvin. You've made a number of things clearer for me. Now I'm off to do some shopping!!

gardenbench,
The best place to orchid shop in the mid-Atlantic region is this weekend at Longwood Gardens in Kennett Square, PA. Sure, it's a bit of a hike from CT but it's WORTH the effort! I will be driving ~ 2+ hours, each way.

--Stitz--

Please, note the link included below. This event is ONLY this weekend.

There are a select group of vendors at this event. Lectures include Venezuelan and Colombian topics on Friday.

--Stitz--

Here is a link that might be useful: Longwood Gardens International Orchid Show and Sale 2010