The camp has been visited by local residents
The camp was set up in the early hours of 25 April and has won support from residents of a nearby estate in Weymouth.
The group also plans to dress up as chickens to highlight tests that showed death rates in poultry increased when they were fed GM maize.
On Monday, the protestors met the farmer who owns the field, near the Littlemoor estate, but so far the demonstrations have remained peaceful.
A member of the group, Liz Snake, said: "We had our first visit from the farmer this morning. He was very polite and it was all non-confrontational.
"We've been here two weeks now and loads of local people have visited us.
"They use this area to walk their dogs and for recreation and they don't want GM crops planted here.
"There were attempts to grow GM maize here last year and the locals destroyed around 70% of the crop."
'Chicken die-in'
The centrepiece of the protestors' camp is a 30-foot high pink castle that was set up at the entrance to the field.
Ms Snake said: "We needed a dwelling over six feet high and the castle has lock-ons and concrete foundations.
"We intend to be here for another month because we think there is only a six week planting window for the maize.
"Most of us have jobs, so we operate on a rotation system and we will leave as soon as it becomes impossible to plant the crop."
Commercial approval
The demonstrators are also hoping to organise a "chicken die-in" that would involve people dressing up as chickens.
They will then cross the field and half the "chickens" would pretend to die.
The demonstration seeks to publicise tests that were conducted on T-25 GM maize, which was approved for commercial use in 1996 by the Advisory Committee on Releases to the Environment.
Chickens were fed the crop and initial results showed twice as many died compared with those fed on conventional maize.