Are these autos ready for bloom nutes?

[DavieTMac]

Have 2 orange critical auto and 2 hulkberry auto in a oxypot 4 that I think are starting to stretch. My first grow. Bit unsure. All between 4 and 5 weeks from popping.

PH fluctuates between 5.8 and 6.1
1.0 EC
25 C air
20 C water
RH is low usual 35 to 39

 

[Habosabin]

Have these showed sex yet? If not, then keep on grow nutes.