After a first year of decent hop growth, I am figuring on laying some compost on top of where the hops are planted before we get snow to help build nutrients for next year. Any suggestions on how thick a layer of compost is too thick for the hops to poke through in the spring, and if I do this every year, will it limit the amount of growth by burying the original rhizome too deep? Any other suggestions on the topic?

Three to six inches of mulch/ compost and then some hay on top of that. Maybe another six inches. The hay will lessen the freeze-thaw cycle that likes to damage cell walls.

Hay!, thanks

Yeah, I'd go with a layer of compost and then a layer of mulch. The mulch will help retain moisture, keep the compost from drying up and/or blowing away, and generally keep your hops happy. The straw mentioned by TBass may not be needed, but it can't hurt... except for the fact that hay can sometimes contain a lot of stowaway weed seeds.

The thickness of the layers of compost and mulch really depends on the compost and mulch and where you live. You are right in that you don't want to bury the plant too much.

Assuming this is a decently established plant and you don't live in someplace that will have snow cover for the entire winter, I'd probably go with 1-2 inches of compost and 1-2 inches of mulch. I'd probably leave out the hay (for the fear of a weed outbreak) unless I lived in a place with some really cold winters. As winter comes to an end, I'd take a look at how much the existing soil has absorbed the compost. If it has not absorbed much, I'd gently remove some of the compost from above the plant to make sure it is not restricted.

If you do live in someplace that will have snow cover for the entire winter, I'd would error on the side of TBass' suggested three to six inches of total cover. Then remove any excess come spring.

Remember that mulch should not sit right up against trees or plants. This can increase the chances of fungal infections. A few inches of space is fine.

-Jeff