Instructions
Go through the Goblin woods to the right. Locate the talking tree at the top of a small hill. Talk to the tree, who will take you to Arthur Spiderwick.
Talk to Arthur. He should mention the bloomer sprites. Walk past Arthur to the north. Locate and pick up the bloomer sprite.
Take the bloomer sprite back to the house. Use the bloomer sprite on the small blooms to make them grow. There are only a few flowers that you can make bloom larger, including the tomato plants next to the garden shed, the plant in the middle of the front yard and one in the back yard.
Use the bloomer sprite on any plant that you come across to see if you can make the flowers bloom.