Getting Kniphofia to Bloom

Four or five years ago, I bought a 4-pack of kniphofias grown from seed. Unfortunately, I've long since forgotten the name of the seed strain, but I remember it was suppose to bloom the first or second year from seed. I planted them in the bed that runs along the west side of the house, which is kind of a difficult location. The sun doesn't start to hit this bed until noon in the summer, and then it gets about 6 hours of unrelenting afternoon sun with reflected heat off the driveway. The kniphofia seedlings grew rapidly, but refused to bloom.

This plant didn't bloom for two years. Clearly it's doing fine now, but why?

My parents decided to bump out the living room wall and put in a large bay window a couple years ago, requiring many plants to be relocated. Bumping out the wall reduced the depth of the bed by over a foot, but the space under the eve, which was uniform across the roof rather than following the recessed wall, wasn't really usable anyway.

The majority of the plants that needed to move were transplanted to the south end of the house, including the Yucca filamentosa I've shown previously, several echinacea, some inherited orange lilies and gladiolus, and two of the kniphofias. The following summer, the two kniphofias that were moved bloomed! And not just a few stalks, but a full show. Clearly they had been large enough to bloom for some time. I assumed that they were responding to the longer duration of full sun they were exposed to on the south end of the house and determined to move the remaining two as well.

A bit past its prime, this was one of the first two kniphofias to be relocated. It bloomed just as well last year the summer after it was moved.

The second of the first pair moved, the same as the one in the topmost picture. This one is darker, blooms a bit later, and lasts longer, but didn't produce as many blooms at once this year.

This spring, I started work on the bed along the west side of the house, moving the plants that hadn't been moved prior to construction, amending the soil, and raising the soil level as well as sloping it away from the house to improve display and drainage. One of the two kniphofias in this bed was moved to the southwest corner of the house with the two that had been moved previously. The other I replanted in the bed along the west side of the house, wanting to know if it would bloom after simply being moved. I wanted to know if it was the greater sun exposure or the move that had triggered bloom.

One of the two kniphofia remaining in the western bed. It turned out to be the darkest of the bunch.

 The plant pictured directly above and below was moved to the southwest corner of the house with the two moved before construction and decided to bloom shortly after the yellow one did. For some reason, it's much smaller than the other three (as in, fewer foliage rosettes in the clump), but it still produced two flower stalks that started out a dark brick red before lightening to orange.

The dark orange above matures to a much lighter orange fading to yellow at the bottom.

So how about the fourth plant, the one that was replanted into the western bed? It took another week or two after the others started blooming, but it did finally bloom! I didn't get a picture of the open flowers, because by the time it opened I was preoccupied with watering during our extended heatwave that has finally ended. It ended up looking like the two darker orange ones at first but matured quickly to look more like the yellow one, with somewhat longer individual blooms. It only produced one inflorescence initially, and that one is all but gone now, but it has at least two more coming in now. The larger two on the southwest corner are also sending up a small secondary bloom now that the first wave has ended.

Searching for blooms on the fourth plant, I found this!

So what did I learn from this? If you want kniphofia to bloom, move them. The one that stayed on the western side of the house might get sun a few minutes earlier than it did in its old location in the same bed, but the biggest change was just digging it up and replanting it. Then again, it has yet to bloom as well as the ones on the southwest corner, so additional sun probably plays a role, too, as it does with many plants. Now I want to know if kniphofia commonly behave this way or if it's a quirk of the seed strain from which these plants came, or even of my individual plants.