Trebah Garden became a virtual island after all the main approach roads were covered with floodwater this morning.
The attraction near Mawnan Smith was closed to the public today after roads became practically impassable, and staff were told not to come in over fears they would be unable to leave if the weather worsened.
Jonathan Bray, the garden's marketing manager, said: "We've had to close because the staff couldn't get in and with the weather getting worse we didn't want them to get stuck.
"The top of the garden is on a hill but the road to Mawnan Smith is flooded, and there's flooding at Treverva, and the coast road is closed any way."
One staff member who did make it in, Jenny Jones, said: "We're cut off if you don't have a 4X4. The water's very deep into Mawnan Smith, and the other way too."