i think it is kinda dry, maybe you need to water them.
This is my method for Phals to grow spikes :
1) In VN, when i want the Phal to grow spike, i reduce the amount of water. ( For example, i usually water my Phals three times a week since it is kinda hot in VN. So i will now only water them 2 times a week or even once a week.)
2) Also, i increase the sunlight a little bit.
3) I fertilize it with a higher level of Potassium like grow more 6:30:30 or 12:0:40 or 10:20:30. I usually use 1/2 teaspoons and dissolve it in 4 litres of water and fertilize once a week. ) but that was when i first knew how to grow Phals. Now i use slow-release fertilizer, it worked . i recommend you to use slow-release fertilizer.
i hope this help )