A Northland lesbian couple has been inundated with offers of support and sympathy after their small flower business was torched in an apparent anti-gay attack.

Blooming Bulbs in Mangawhai Heads, a seaside town about 100km north of Auckland, was destroyed by fire on Saturday.

Owners Juliet Leigh and Lindsay Curnow operated the business from a small packing shed next to their home.

A week before the fire, the couple's house, cars and shed were scrawled with abusive anti-gay messages.

The attacks have outraged the people of Mangawhai, with one woman buying the couple a bouquet of flowers and saying she was "just so ashamed", The Northern Advocate newspaper reported.

Ms Curnow said the couple had received about 500 emails of sympathy and support.

One from Tauranga offered to put up the couple "if you want to escape and stay with us for a week".

Another couple arrived with fresh home-made bread.

"The response is amazing and making the horribleness seem more distant but, actually, we are frightened," Ms Curnow said.

A relative with a dog had come to stay.

Ms Curnow said the attacks had worried the gay community.

"We are really puzzled. We have been here seven years and never had a cross word with anyone in the district."

The couple estimated the cost of the physical damage to be about $100,000, not including the loss of the business.