I have a few pentas and angelomia and they are tall. It's Nov. Is it too late to trim?
Where you live, you should be still ok to prune these plants. Weater has been funny the past few years though, so if you expect you will get a cold snap in the next month or so, hold off until spring.
My pentas are wonderful. Can I move them to an area in the ground and will they continue to grow? Will they have to be replaced next spring?
They will not winter over in the ground but you certainly can plant them out as an annual.
https://www.gardeningknowhow.com/ornamental/flowers/pentas/growing-penta-plants.htm
Is it too late to plant pentas?
In colder climates Pentas are generally treated as an annual, so may want to start plants in the spring.
Here is a link with more information.
https://www.gardeningknowhow.com/ornamental/flowers/pentas/growing-penta-plants.htm
Will it survive the Arizona summer heat? If so, should it get afternoon shade?
You should plant Pentas in part shade to part sun.
A morning part sun location would be fine.
https://edis.ifas.ufl.edu/fp465
https://www.gardeningknowhow.com/ornamental/flowers/pentas/growing-penta-plants.htm
Leaves look wilted...am I watering too much or too little? The flowers look dried up also. Should I pinch them off and, if so, how far down?
Your Pentas should be potted in a well draining container with a good quality potting mix.
The soil should be moist but never soggy. Check the soil, instead of watering on a schedule.
Wilting can be the cause of root rot from too much water or not enough watering reaching the roots.
Flowers can be dead headed when they fade, you pinch of the ends of the stems.
Here is a link with more information.
https://www.gardeningknowhow.com/ornamental/flowers/pentas/growing-penta-plants.htm
Growing Pentas in Florida - Full sun or shade?
Dappled sunshine would be a good light situation, shelter from the hottest sun of the day.
https://www.gardeningknowhow.com/ornamental/flowers/pentas/growing-penta-plants.htm
Everyone says to deadhead a pentas, but I can't figure out where to cut. Each stem seems to grow three flower clusters. Am I supposed to pinch off each flower cluster as it dies or follow the stem all the way to the leaves and cut there (sacrificing the two side flower clusters)? For example, when I clip just the center cluster (leaving the two side ones), the side ones eventually die and I have to cut those too. I end up with lots of pitchfork looking stems from where I clipped each of the three flower clusters as they died. Do I cut the whole stem at that point? They never seem to grow new clusters or leaves. Help! I love the flowers and feel incredibly guilty when I lose a plant. :-( Thanks in advance!
It is your choice whether to remove the individual dried flower cluster, remove the whole stem with the live side clusters too, or leave the dried cluster on the plant until the side clusters die as well. Whichever you think looks best is fine, and none will hurt the plant.
Thanknow you!