So, I am creating this guide in order to share what little I know on how to use the seed Item. I have done very little experimenting and will update this guide as information comes in.

Image shows a tree that provides 3 resources, 2 ore and 1 water. The seed was placed on a water resource and the roots extended to 2 ore blocks. The tree seems to require the 9 blocks, 3x3, above it to fully grow.
So from this we can extrapolate that the tree will provide the resource it grows on and the resources it connects to via roots. The roots themselves make the block they pass through more difficult to mine.

• Place seed near middle shaft for easy access
  
  
• place on cobalt when possible for added security, especially if you are finding it hard to stay alive
  
  
• plan ahead, It might be worth saving nodes if they are in a good location
  
  
• The tree takes a few rounds to fully grow, about 6, but provides every cycle.
  
  
• This is useful especially in Prestige mode.
  
  
• Place seed next to a max of 3 resources, any more will not help.
  
  
• You can remove the seed once it has initially began to grow by digging up the block that is directly below it. (don't know if it works if it is already providing resources).
  
  
• According to comments, If seed is placed on normal ground it will provide with one iron.