Orchids looking ok but will they flower?

[Goosegirl]

I moved my orchids onto my kitchen windowsill and they seem to be doing well. I'd like some advice so I can get them to flower.

[Paphluvr]

Can you tell us more about your growing conditions? Examples would be: exposure (n,s,e,w), day & night temperatures, humidity, fertilizing schedule, watering schedule, etc. We'll be able to help you better with more info.

[rbarata]

I don't think anyone can answer that question. It's just a matter of wait and see.

[Ray]

Those are phalaenopsis plants. The warmer you can grow them (with no direct sun), the better they will grow. Feed them regularly, but keep the fertilizer concentration low.

Flower spikes will be reliably initiated once the plants have been exposed to an average growing temperature that’s about 7-10C lower than the average temperature they had been experiencing the rest of the time. After that exposure, return them to the warmer conditions and the flower spikes will emerge about 6 weeks later.

[Arizona Jeanie]

Ray's advice about temps works perfectly for my phals. Here's how I manage it: mine are outdoors on a screened porch during the summer. When temps start to drop in the Fall, I bring them in to a room I can close off, block the heater vent, and open windows as needed. I use an inexpensive indoor/outdoor thermometer to monitor the temps and adjust the windows. I do this for about a month (probably longer than necessary), trying to keep the room above 62F. I then close the windows, open the heater vent and the door, and let them come up to normal house temps. Some will already be spiking, others will start a few weeks later. They've bloomed every year since I started doing this, it's worked great for me.
You do need to keep them otherwise healthy, getting the proper light, food, water and potting mix.
Mine are blooming now, so nice to see. Thanks Ray!

[JScott]

Ray is right about the temperatures. In the massive greenhouses where these are mass produced, they can fiddle with the temperature to initiate spikes in order to have plants to sell in bloom all year long, however once you are growing them in your home, they generally only bloom once a year, in the winter.

I keep mine outside in bright shade from late spring into fall. when both day and night temperatures are out 15 degrees below than what they are used to, I leave them outside for a couple more weeks and bring them (In north Texas, this usually happens in October, or maybe even early November, but I don't ever let them get below 55 degrees, and that's pushing the limit. 60 degrees is probably safer). A few weeks after I bring them back in, I start to see the little spikes poking out.

The point is that Phals are naturally seasonal bloomers, and even if you bought it in bloom in May, you may have to wait until winter for it to bloom again when it is exposed to the proper temperatures in the fall.

And just a side note, some plants are just later bloomers than others. Six weeks after exposure to cooler temps is probably an average time you can expect before you see spikes start to form, but if it doesn't happen in six weeks don't panic. It's March, and I've got a couple Phals that are just now starting to show their spikes, and that is typical for those particular plants. They always spike later than the others.

[aliceinwl]

For almost all of mine the seasonal drop in temperatures they experience on the windowsill is enough to trigger blooming. Light must also be good: those on low light windowsills don’t bloom reliably. Sometimes if you let the heat drop into the low 60s at night this can be enough to get them blooming too. Lots of light combined with a seasonal temperature drop seem to be the two key elements.

[Connie Star]

To my eye most of them look a little small to start blooming. There are also "bloom booster" fertilizers that might help, but as has been said, temperature is key.

[Ray]

Originally Posted by Connie Star

To my eye most of them look a little small to start blooming. There are also "bloom booster" fertilizers that might help, but as has been said, temperature is key.

Bloom booster fertilizers don't boost anything.

The first commercially-made mineral-based orchid fertilizer was Miracle Grow 30-10-10, developed by Dr. O Wesley Davidson of Rutgers University. (Cut-flower orchid growers were centered in NJ and Long Island after WWII, having been moved there from England to avoid the Blitz). It was heavily applied and the plants grew great. However, after a while, growers started noticing a reduction in flower production, due to the overapplication of nitrogen.

They formulated another blend adding cheap phosphorus compounds to dilute the nitrogen content, and courtesy of a little marketing, the "bloom booster" was born.

it doesn't "boost" anything, but if you've been over applying nitrogen, stopping and switching to it "allows" the plant to bloom normally.

[Goosegirl]

Mine are on a north-facing windowsill in our small kitchenette so I'll try moving them to a place that has more light. Both my open-plan dining and sitting rooms have a south-facing window sill so I'll give it a go and see what happens. At least, they're still alive and pushing roots out which is more than I expected.