It depends on what kind of node you started off with, the nodes around your main node and a lot of other factors. Silverwood trees do help get rid of flux slowly over time but the effects they have on aura nodes can actually bring more flux to an area. From what I've found out so far planting silverwood trees near enough to a node will inflate its size, and enable it to take in more aura and flux from nearby nodes. I believe it also creates some flux when a silverwood grows. Once a node gets big enough it will also start to suck in any nearby small nodes, which tends to be bad as those nodes were helping your main node offload its flux and recharge its aura.
However if you plant a silverwood tree somewhere not near a node it will create a new, tiny 'pure' node, which will help other nearby nodes get rid of flux. These are the ones you want to grow a bit as they will help out your main node. Just try not to have them all start fusing with each other and creating power imbalances.
Essentially using silverwoods to inflate one node generally breaks the quite efficient node network that was already there naturally, you're best off trying to create pure nodes surrounding your main node to help it recharge and purge itself of flux. Now you have high flux though it will take a very, very long time to dissipate. As far as I can tell so far there's not a lot of ways to speed along the purging of flux, you just have to wait for lightning and wisps.
