The instructions you prepared for the cache will be really useful for you to plant the tree. In my case, I'm planting the Japanese Red Maple according to all the instructions at a location in Chicago. I'm also placing some of those seeds in the cache as trade items.
What you would do with your cache is upto you. You decide the seeds you want to trade, download the template "Seed_Planting_Instructions_Template.doc" and put in all the information the seed traders would want access to so that they can plant and maintain the tree.
Here, in this project there are two things to plant/hide and maintain. The tree itself which needs constant maintenance and the cache which constantly keeps changing based on geocaching members visiting, logging and trading away.
Firstly, you plant your tree during the best time of the year for them to start.
Secondly, you take your prepared cache with seeds, instructions, instruction template copies for visitors to take, geocoins, tradable items and other items (part of a normal geocache which you can read about at their site) to the location where you planted the tree.
Thirdly, in accordance with the guidelines at geocaching.com, you hide it in a location in and around the latitudinal/longitudinal location of your tree and submit the cache to geocaching.com in the form provided by them at this link
With this step you will be all set to watch your tree grow and maintain the cache that is close to it.
Watch it as people visit your tree. Notice if they actually engage actively in seed trade. If they do, t
they will start their own geocache-a-forest with this DIY kit. Eventually, you have a geocache that is attached to a location where your tree is growing with people logging in the stage at which your tree is in, documenting its life along with the life of your cache.