The teachers were among 4000 who responded to a survey by the organisation Child Forum.
Eleven percent of the respondents said their centre usually operated with fewer than the legal minimum number of staff, and half said they were required to clean the centre at the same time as they were supposed to be teaching.
The percentage of respondents who said they would not send their own children to the centre they worked in, 26 percent, was almost exactly the same as in two previous surveys in 2014 and 2017 which elicited much fewer responses.
Some respondents said the owners and managers of their centres did not care about children's welfare, and some said they did not feel safe.
"They don't care about the actual children," wrote one teacher.
"I feel they are like prisons," said another.
One respondent said: "ECE (early childhood education) has become baby farming. Too many kids, not enough space, not enough nature and relationship with nature, long hours, and poor food quality provided."
"The noise and constant stressful atmosphere aren't OK, plus the children are always hurting each other due to boredom," said another respondent.
Child Forum chief executive Sarah Alexander said the percentage of respondents who would not send their own children to their centre was "shockingly high".
"There really needs to be improvement so every child in every publicly funded early childhood service gets to experience ECE that is safe," she said.
Alexander said policy-makers should pay more attention to early childhood teachers.
"One of the things respondents said is what is written down on paper, on the records that go to the Ministry of Education, or on the brochures that are given to parents, will be one thing but what we know to be happening on the ground here in reality is something else. The problem is we're not hearing what is happening behind closed doors," she said.
The survey report said 74 percent of respondents said they would send their own children to the centre where they worked, but 26 percent said they would not.
It said 29 percent of respondents did not get enough time to form individual relationships with the children they worked with, up from 26 percent in 2017 and 17 percent in 2014.
The report said teachers complained there were too many children and not enough teachers.
"Most of my attention is therefore focused on the children who are putting other children in danger - biting, hitting, kicking, throwing blocks. The quiet children miss out. I am failing the 'good children'," said one respondent.
"I am a qualified teacher with a non-qualified lazy teacher. And I have 26 kids in my room. It's crowd control," said another.
The report said 46 percent of respondents worked in centres that met minimum teacher: child ratios, and 39 percent in centres that exceeded the minimum ratios.
However, 11 percent said their centre usually did not meet the minimum ratios. It was the same figure as the 2017 survey and slightly lower than the 12 percent reported in 2014.
Some teachers told the survey their centre counted staff doing office work as being "on the floor" working with children, so that their official paperwork showed they were working within ratios even when they were not.
"When a reliever cannot be found, staff in the office are put in the books as being 'in-ratio'," one said.
"The manager is often rostered onto the floor so on the books it looks like she is in ratio, however she is always in the office during those days. This makes us way below ratio and makes it very stressful," another said.
The report said half the teachers said they were required to clean their centre.
As one respondent explained: "primary and secondary teachers wouldn't do this kind of cleaning".
"However, the proportion of teaching staff in community-owned centres required to do cleaning when they were on the floor with children was significantly less than in private centres (32 percent and 57 percent respectively)," it said.
Survey respondents were invited to participate via emails to their early childhood centre managers, and via early childhood internet groups, in January and February.
Child Forum closed the survey after more than 4000 responses.
It said most of the responses came from teachers in community-based or privately-owned early childhood centres, with only a few percent from kindergartens and home-based services.