Chloe Dunstan, who blogs at Chloe and Beans, is mum to Evan, four, Otto, three, Felix, two, and 11-month-old triplets, Henry, Rufus and Pearl.
She said her boys are clean, happy and comfortable, and she doesn't understand why people feel the need to comment on their hair.
"Male hair has the ability to grow long, just like female hair," she sarcastically wrote on Facebook.
"Sometimes people tell us it needs to be cut off because it's too heavy, uncomfortable, too hot or unclean when it's long; if that's the case, I'm just wondering why we shouldn't shave girls' hair off, too?
"Is it because boys are allowed to be more comfortable than girls? And girls should sacrifice comfort for aesthetics? I dunno, you tell me."
Dunstan said people have warned her that her boys "may get picked on" for having long hair, too.
"So teach your children not to bully people for how they look," she continued on the '101 tutorial'.
"That would be a good start. I will never teach my kids that they should change the way they are just to avoid comments from small-minded people.
"And even if my boys 'look like girls', that's fine by us! Why would looking like a girl be a bad thing?"
Aside from that, Dunstan said she has no problem with people wrongly assuming that her sons are girls.
"It happens 99.9% of the time when we are out and I just say: 'Oh, they're actually boys', and the kind people say: 'Oh okay, oops!" but the assholes say: 'BOYS? ARE YOU SURE?'
"Why do people even care if they're boys or girls? There is actually no reason you need to know what a child has between their legs. No reason. At all.
"Some kids don't like having their hair cut. My kids don't like having their hair cut. They get really upset about it actually. I don't want to upset my children."
"My kids are clean, comfortable, kind, healthy, happy and confident with who they are," the mum added.
"This is what matters most. Their hair is actually fabulous."
Dunstan's post was liked more than 3,000 times in one day and it encouraged other mothers who have sons with long hair to share their own pictures.