When trials of the foundation phase began four years ago, some branded its play-led philosophy too "hippy-like". Critics envisaged children being left to run wild under a curriculum that lacked structure.
But teachers and parents at Steiner schools believe the learning-through- play strategy is too prescriptive and does not go far enough.
Many parents in the UK, disillusioned with mainstream education, are turning to the controversial schooling method. But there are just two Steiner schools in Wales.
Nant-y-Cwm in Pembrokeshire is one of these. Janet Brackenbury, a kindergarten teacher there, said the foundation phase used only "superficial" aspects of Steiner education, which is all about play: "It's supposed to be about play, using natural materials and a lot less emphasis on the academic side."
Steiner Waldorf education, based on ideas expounded by the German philosopher Rudolf Steiner just over a century ago, is based on creativity and co-operation.
Although Nant-y-Cwm's 30 or so pupils are not formally taught the three Rs until around the age of seven, inspectors awarded the school a grade 2 last year for all seven foundation phase areas, including maths and language skills.
For Steiner teachers, this is a vindication of their methods, proving that young children can absorb important information naturally through play and that there is no need for more formal education until later on. It is a theory practiced by all Scandinavian countries.
Ms Brackenbury became disillusioned with pre-school state education as a reception teacher.
"I was teaching children who were put in special needs classes because they found reading and writing hard. But I felt there was no need; they just weren't ready yet."
She said parents have many reasons for sending their children to Steiner schools, including bad experiences in class, but many feel mainstream schools are pushing their children to learn too early.
One parent at Cardiff Steiner Early Years Centre, which has around 20 children aged three to seven on its roll, said she had decided to teach her children at home once they finished kindergarten.
Both Welsh Steiner schools have a clear daily routine which, for under-7s, includes plenty of free play. Toys are minimalistic and made of natural materials. They are often unbranded - even Lego bricks are deemed too prescriptive.
Ms Brackenbury said this leads to more co-operative play.
As with the foundation phase, pupils also play outdoors every day, regardless of the weather.
Last year, the first state-funded Steiner school opened in England, but Wales's are both independent.
Ms Brackenbury said in past years Nant-y-Cwm has had up to 200 pupil, but now many cannot afford the fees, which are advertised as pound;280 per month.
"We would love government finances, but not if we had to compromise on what we teach," she said.
- One teacher
A teacher stays with a group of pupils, not a year group, so they get to know each child individually.
- Immersion teaching
After kindergarten, each subject is taught for a three or four-week block, after which a different topic is chosen.
This expressive movement is used in all Steiner schools to improve creativity and physical development.