There's a big red shoe on wheels and this is the shop. Kick it to enter
You need to buy and put on a gardener outfit in the 6 ticket tab
Then leave the shop, walk into the garden behind it and this will pop
If it doesn't pop from just walking in the garden then kick the golden carrot in it and it should pop
See in video at 3:15
Achievement Walkthrough - Updated to 3000GS: