I think that we should change a little the mechanic of the Celestial  vines with adding a notion of distance. Normally, a vineship puts 10  turn to spreads her roots, without a notion of distance with the system  where they leave, if the system that the player wants to root is not far away, it still take the same time if the target was farther. This change could force the player to think better about which system to choose to extend without loosing too much time.

Adding other modules of distribution of roots could allow the player to reduce the time required during the game and to allow  him to continue to extend his network of roots without too many difficulties.

I hope that you will see my idea and considered it.