So you are saying you have not fertilized since you purchased these plants? That is a very good thing. Their time at the nursery you have no way of knowing. One could have been in the greenhouse under the artificial lighting, another might have sat on the truck in cold conditions and the dark and who knows what formula and when they were fertilized. It takes time to get situated to be in sync with new plants.
It doesn't take much to set back flowering such as too high of Nitrogen in relation to the Phosphorous and Potassium (NPK). Nitrogen promotes vegetative growth like leaves, less in relation to P and K and that promotes reproductive growth.
Any flowering needs light! More than just a window sill. Remember, your plants were raised with excellent artificial lighting. Is it a south facing window sill? Double pane windows? Near forced air vents? Raise the bottom of your pots off the surface using tiles or 'pot feet'. I would also add a grow light...check out what wattage, lumens, amps are necessary for a grow light on this site. Get a timer to allow for a day and night time that coincides with the sun outside your window. Otherwise, these plants are meant (seriously) to be a very short term perishable. The stores including IKEA want you to fail so you come back to buy more! Otherwise, plants should come with a huge information sheet to address all kinds of consumer situations and questions
Pruning the flowers off is a very good thing as that transfers the energy of making seed into the entire plant, leaves, stems, roots and then the flowering takes off big time. But not too much all at once because this is a succulent. Also because Kalanchoe is a succulent be careful with watering. Succulents store a lot of water for dry times...
Make sure you have pots with drainage holes, use ONLY potting soil, no rock/gravel/packing peanuts above the drainage hole and the soil...use JUST soil to fill your pots/containers. The best pots for succulents are clay and are wider than tall. Think about one big long pot/container to plant all of you Kalanchoe en mass and offset. I'd also find a companion plant that has the same needs as Kalanchoe perhaps being able to display some color when Kalanchoe is not flowering. (partial shade, succulent or prefers dryness in between waterings, shallow rooted, stays below the height of your Kalanchoe..shoot, I'm a drawing a blank on a few names at the moment. Just go look up succulents and find one that drools over the sides and stays low)...
Use Osmocote 14-4-14 if you are new to fertilizing. Extended release, you'll only need to use once maybe twice per year! Yes, the N is equal to the P and K and that works for blooms and vegies. Fertilizer IS NOT FOOD for a plant. Just necessary to have in the medium for the plant to use to make its own food via photosynthesis. MORE is death to plants. A very quick and usually certain death. That is why I recommend Osmocote. Do not worry about ORGANIC versus SYNTHETIC. Chemicals are the SAME no matter! Osmocote is safe and sure for newbies!! Wait for awhile before transplanting or fertilizing...oh a good half a month? SEND PICTURES, what is your zone or where you live, what window are they using as much as you are able.
Growing a whole bunch of ONE plant is a visual treat! You'll get lots more bang for your buck and for the work of propagating you've done. Have patience. When you've got your plants in the same soil, same environment, same watering schedule and same fertilizer...you'll have an awesome display.
