Straw mulch depth?

[BaylessBrewer]

So I have my bed ready for my rhizomes (arriving in the next day or two) and I just ran some chicken wire around it and put about 6" of straw on top of the dirt. I plan on cutting sections from a round gallon jug to put over the rhizomes to form a doughnut to keep the straw away from any growth that emerges.
My question is : is 6" of straw enough, too much or just about right? It's a raised bed with a mixture of compost and top soil with some bone meal turned in. I want to keep potential weeds at bay and at the same time minimize the amount of water required. If that's even possible.

 

[BaylessBrewer]

Maybe pictures are better than words. Rhizomes will be here tomorrow (fingers x'ed) View attachment ImageUploadedByHome Brew1459345245.593921.jpg

 

[alane1]

I'd say it's probably deep enough, as long as there's no perennial weeds lurking below the surface.

 

[BaylessBrewer]

I'd say it's probably deep enough, as long as there's no perennial weeds lurking below the surface.

I don't think there are any weeds that will get up to the surface. I turned the soil/grass over and then anchored the 2x8 walled box to the ground and filled it with compost and top soil out of bags.

 

[HALIFAXHOPS]

In my field I lay about that every year over the beds and it packs down to about a 2" matt by the next spring. The hops will grow right through it as they emerge so you do not have to cover them unless you want to.