I have a bougainvillea that is just not growing in its 2-3 year ago planted location. It was maybe 18" tall when planted and has died back each winter. (I live in Palo Alto, CA; we had several below freezing nights both past winters) What is left is about 3-4 inches of 'trunk' and 1-2 4-inch springs of new growth. It wants to live, but evidently not there. Can I dig it up and put it in a pot? Or, fix it there ....?
It thrives in zones 10-11 and your hardiness zone is 9b to 10, so you are right on the edge. You can move it to a container and bring it inside for the winter if you think that is the issue, or mulch it real well before winter. Otherwise, try moving it to a place in full sun with well drained soil. Fertilize it regularly and pinch back the tips to encourage fullness. These articles should help:
https://www.gardeningknowhow.com/ornamental/vines/bougainvillea/bougainvillea-garden-care.htm
https://www.gardeningknowhow.com/ornamental/vines/bougainvillea/bougainvillea-in-containers.htm
https://www.gardeningknowhow.com/ornamental/vines/bougainvillea/pruning-bougainvilleas.htm
https://www.gardeningknowhow.com/ornamental/vines/bougainvillea/bougainvillea-winter-care.htm
I planted a small bougainvillea in a large ceramic pot. A root from the plant has escaped the single drain hole and is appx 16 inches long. Can I cut that root without damaging the plant? I love a bougainvillea and potted it so that I may take it with me when I move into a new home. Thank you!
Bougainvilleas are pretty tough so I believe it will be fine to cut that off.
https://www.gardeningknowhow.com/ornamental/vines/bougainvillea/bougainvillea-in-containers.htm
protected by a low wall. It is very healthy but has no flowers. It is watered about every 2 weeks.
Since it is in a container and it is very hot, it needs to be watered more frequently. A moisture-stressed plant won't bloom. It also needs fertilizer or compost on a regular basis. A slow release fertilizer works well, as it supplies nutrients every time you water.
This article should help:
https://www.gardeningknowhow.com/ornamental/vines/bougainvillea/bougainvillea-in-containers.htm