Operation Armscote is believed to have put a major dent in an organised crime-linked grow house syndicate operating throughout the ACT.

In a media statement, police said they had seized 1226 plants with an estimated street value of more than $7 million, which were allegedly being cultivated in hydroponic setups in rental properties across the city.

The investigation began on June 12, when police found a grow house in Kaleen.

Over several weeks, police uncovered a further nine grow houses and arrested six people on drug charges.

Police raided homes in Calwell, Downer, Harrison, Hackett, Macgregor, Nicholls and Weetangera.

Just last week, 89 plants and more than $20,000 in hydroponic equipment was seized from a house in Bonner.

Police say it is the most extensive grow house network in the territory's history.

They believe they have disrupted a highly sophisticated and organised crime syndicate.

The network has operated largely from rental properties across the ACT in the past six months.

Many landlords are thought to have been unwitting victims of the grow houses, which caused extensive damage to some properties, police say.

On Wednesday, four people linked to the operation were brought before the ACT Magistrates Court.

Poh Beeg Lim, 53, Kam Mei Ng, 36, Pei Yeon Wong, 30, and Ong Yap, 35, all pleaded not guilty to offences of either participating in a criminal group, cultivating cannabis, or both.

Court documents state Lim had sent forty thousand dollars to "beneficial recipients" in Malaysia.

Yap was the only of the four to apply for bail, but the matter has been adjourned until Friday, to allow prosecutors to take instructions.

The matters of Lim, Ng, and Wong have all been adjourned to September.

All four remain in custody.

Lim is expected to contest his committal to the ACT Supreme Court.