"We had seven relievers on our list that picked up fulltime work over the last school holidays ... It is getting really hard," he said.
"There needs to be more recognition of our teachers. I don't know many teachers that fit the 9am to 3pm model."
Merivale School principal Tom Paekau said he was also struggling to find relief teachers.
"That is a Tauranga-wide problem," he said.
Paekau said the school's roll had jumped from 122 to 140 pupils since January and employed 10 teachers.
"We are almost at the stage where we need to open a new classroom ... but we don't have the learning space. If we got to 160-170 we would be at capacity," he said.
Paekau said bigger class sizes and low pay turned people off the profession, saying "it is not a career choice for people now".
Paekau said, in his view, the biggest "hook" to recruit more teachers was highlighting the important role they had in shaping children's futures.
"You are moulding young people to be future leaders. If you ask teachers they are not in it for the money, they are in it for the kids," he said.
The principals' comments come after the New Zealand Education Institute's projections, provided by the Ministry of Education, showed there would be 40,000 more primary school pupils by 2030.
NZEI calculated that at a teacher-student ratio of 1:22, an extra 1815 teachers would be needed to cater for the demand.
"At the current rate of churn, we are swiftly moving from a crisis to a disaster," NZEI president Lynda Stuart said.
Tauranga Special School assistant principal and NZEI Tauranga branch lobbyist Andrea Andresen said not enough students were choosing to study teaching.
"Young people are not seeing teaching as a desirable occupation," she said.
Andresen said housing shortages in places like Tauranga and Auckland were also putting off potential applicants.
The latest monthly QV House Price Index showed Tauranga's average home value was now $702,850.
The base primary teacher salaries range from $47,980 to $71,891 for someone with a teaching degree.
Base secondary teacher salaries range from $47,000 to $78,000, depending on the qualification they hold.
However, Ministry of Education deputy secretary of early learning and student achievement Ellen MacGregor-Reid said plans were in place to ensure there would be enough teachers to cope with the projected increase in pupil numbers, she said.
"We are aware of the projections that's why in Budget 2018, $370 million was set aside to fund 1500 more teacher places by 2021 to meet population growth," MacGregor-Reid said.
Minister of Education Chris Hipkins said the Government planned to address a 40 per cent drop in the number of people training to be teachers in the last nine years.
"There are certainly some challenges with teacher supply, especially around ensuring we've got enough teachers in the right place in some parts of the country," he said.
Hipkins said a $9.5 million teacher supply package was announced last year and a further $20m was provided in Budget 2018 across the next four years.
University of Waikato associate dean of teacher education Beverley Cooper said there was an increase in teaching applicants but not enough to meet the demand.
Cooper said this year the university had about 50 students in its primary school teacher education programme.
That was a 50 per cent jump from the number of students enrolling last year, she said.
"That is an indication that people are understanding that there is going to be a teacher shortage."
Leader of the Opposition and Tauranga MP Simon Bridges said the teacher shortage was partly due to the booming economy and more opportunities for teachers to switch careers or start their own businesses.
Bridges recently announced National's commitment to attracting more teachers and ensuring they were highly-respected professionals in their communities.
"Part of that is pay, but it's also about conditions like smaller class sizes and the investment we put into teachers to deliver quality teaching and learning to our kids."
Primary school teachers and principals have voted for a full day strike on August 15.
THE GOVERNMENT'S PLANS?
- The Ministry of Education has received around $1.5 billion in new capital funding (including $332m in Budget 2018) to deliver around 45,000 new student places across New Zealand from Budget 2014 to Budget 2018.
- Around 20,000 spaces will be provided through a mix of funding for 24 new schools, 11 expansions of recently built new schools, eight new Kura/special character schools and three special schools.
- The remaining 25,000 student places will be delivered by adding teaching spaces to existing schools.
Source: Ministry of Education