It's not all about the Eden Project, Cornwall has so many gardens it's hard to pick one from the other. Visit in the spring to see them at their best, when the native flowers provide as much colour as the imported rhododendrons, azaleas and camellias. Alternatively why not visit in the autumn when the leaves are turning and the Cornish countryside is a tapestry of reds and browns.
Many of the great gardens of Cornwall are open all year round, benefiting from the gulf stream that protects them from frosts. You will find lost gardens, walled gardens, even Japanese gardens… all scattered across the beautiful Cornish countryside, itself a 'garden' worth visiting.