Two Greenpeace protesters who destroyed a CSIRO genetically modified wheat crop will have suspended jail terms hanging over their heads for the next year.

Justice Hilary Penfold on Monday sentenced Jessa Latona and Heather McCabe to nine months, suspended on entering a 12-month good-behaviour order.

Latona, 36, and McCabe, 49, had pleaded guilty to one charge of damaging or destroying Commonwealth property.

The ACT Supreme Court judge questioned whether Greenpeace ''cynically'' used junior staff members of good character in the hope of lighter sentences in court.

Latona and McCabe, both volunteers with the conservation group, scaled 1.8 metre fences to break into a CSIRO farm in Belconnen on July 14 last year.

They filmed themselves vandalising a trial crop of wheat which had been genetically engineered to increase its nutritional value.

Greenpeace used the incident to garner publicity over the issue of genetically modified crops, releasing video of the women destroying the wheat with whipper snippers.

The crop was being grown with a view to testing the quality of wheat and dough produced from the modified harvest.

The protest stemmed from the CSIRO's refusal to release documents under freedom of information laws, saying they were commercial-in-confidence.

The court heard Latona and McCabe were environmentally conscious women with a keen interest in food quality.

They had no criminal records at the time, and Latona has since given birth to her first child.

The pair have since said they regret their actions, and the court heard they did not initially appreciate the full consequences of their actions.

In the aftermath of the protest Greenpeace paid $280,000 in reparations to CSIRO.

Justice Penfold on Monday said the act was clearly carried out at either the instigation of, or with the backing of, Greenpeace.

She said she hoped Greenpeace was also unaware of the full ramifications of the act, rather than ''cynically'' exposing junior staff members to the justice system.

Outside the court Greenpeace Australia-Pacific head of programs Ben Pearson welcomed the verdict, but said the two women knew what they were getting into.

''With all due respect to the judge all Geenpeace employees, activists involved in these types of activities, are fully briefed on what will happen and the consequences of what will happen,'' he said.

''Nobody does this in ignorance of the consequences.

''Jess and Heather are people of honest integrity.

''They undertook this action with their eyes wide open.''

The judge also recorded convictions against the two women.