The Gardener can be found in the second area of Rose Town, northeast of the main area. He cannot be visited until Bowyer is defeated.
Seed and Fertilizer[]
Initially, the Gardener will talk about a super rare Seed and Fertilizer that he seeks to grow an incredible plant. He will reference the Anti Shy Aways as the ones rumored to hold them.
In fact, the Seed and Fertilizer can each be found by one of the Anti Shy Aways, in Bean Valley and Ice Cave, respectively.
Delivering both these to the Gardener will result in a giant beanstalk growing that leads to Ozma.
Flowers[]
Once the Seed and Fertilizer have been delivered, the Gardener will mention a further interest in flowers.
Specifically, he will pay 100 Frog Coins for Gold Flowers and 100 Galaxy Coins for Shiny Flowers. It is highly recommended to only sell to him once the flowers have first been handed over to Daisy and Rosalina.