Tree Harvest Charms were introduced to the game on May 13, 2010. It is a one time use item can be bought for 60 MC. The description reads "Trees ready to harvest? This charm will harvest them all in one fell swoop! Note: One time use!"
To use one, you have to first purchase one. You can find these under the "Trees" tab in the Shop, not the "Boosts" tab. A prompt will appear and ask if you want to purchase it for 60MC. If you click yes, the item will then appear in the storage tab of your inventory and you use it from there. If you click no, you can go back to browsing items in the shop.
From the inventory, click to use it, another prompt will ask if you are sure you want to. Click yes to use, click no and leave it for another time. After clicking yes, you will get all the normal amounts of experience and coins that you normally would get if you harvested the trees manually, although the pop-up will only tell you that you got the coins.
Tip for Island ExpansionsEdit
When you use a Tree Harvest Charm, ripe trees are harvested only on the island your avatar is currently on. If you have an Island Expansion you also want to harvest with a charm, you need to go to your other island (by clicking the Ship icon in the Toolbar) and then use an additional Tree Harvest Charm.
It is best to use the Tree Harvest charm only after all the trees are ready for harvest, so that its effect is maximized. By doing this, you will synchronize all the trees on your island, so long as they all have the same length of harvest time (so for instance, all of them have 2 day harvest periods). Synchronizing trees also provides the benefit that you can log on at approximately the same time every time and harvest it all, rather than harvesting a cluster of trees here, then a cluster of trees there. If you do it fast enough, few or none of your trees will be stolen from by your neighbors since the charm works far faster than a human clicking ever can.