Harvest the food when you have farm.

Players can harvest grown crops by clicking on the patch when it is fully grown. Harvesting of allotments, herbs and hops requires a spade in the player's inventory. Fruit trees, bushes, and flowers do not require any type of tools; they are picked by hand. If your inventory becomes full while harvesting, the Tool leprechaun will note them. This is accomplished by using the harvest on the Tool leprechaun, this includes clean herbs as well. Wielding Magic secateurs will increase the amount you can harvest from your allotment, herb, and hops by 10%. Only willow branches are harvested in the wood tree family. Otherwise, a wood tree is cut down to obtain logs and dug up to obtain roots.
For the majority of plants, the amount of produce harvested is affected by the player's Farming level, whether or not they are using Magic secateurs or an Amulet of nature, and the quality of the compost applied.
Note: Harvesting of bushes, fruit trees, allotments, flowers, hops, and herbs only requires clicking once as of the update which occurred on 6 October 2009. In addition to the auto re-pick function, the animation for picking herbs from patches was also updated.