Police found the plants in the property's carport, a garage at the rear of the property, and an upstairs bedroom.

Leading Senior Constable Narelle Smart, of Ararat, said police entered the property about 9am and arrested a 50-year-old male.

"As soon as we opened the door there was a strong smell of cannabis," Leading Senior Constable Smart said.

"It was a peaceable entry and we've located the target suspect at the front door. We've done a quick sweep of the house and discovered the plants.

"Upstairs in the house there's three bedrooms that had the makings of grow rooms. There were 103 (seedlings there) alone."

"In the carport there was close to 250 to 300 plants just in that room and ... in that back shed you're probably estimating another 100 to 150 plants."

A police botanist travelled to Ararat from Melbourne to assist with the operation.

Leading Senior Constable Smart said police had been monitoring the property since November.

"There was suspicious activity, and we noticed there was a lot of piping put along the side of the house," she said.

"There were electrical cables coming from different areas of the house too, so we did a few surveillance jobs on it."

Leading Senior Constable Smart said police discovered two electrical bypasses on Tuesday that posed a serious fire risk.

She also said the person arrested "didn't have much of a criminal history in relation to drugs".

Leading Senior Constable Smart said she was pleased to be able to make the streets a bit safer.

"A few of our (police) members ... are born and bred in Ararat and we don't want drugs on our streets. It's our kids, our families' kids, our friends' kids," she said.

The suspect is assisting police with inquiries.

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