So again, I will start off by saying I don't have ideal soil for grapes. Fairly heavy clay that can be a bit waterlogged in the spring and fall. That said some of my varieties (concord, polar green) are growing like gangbusters despite this.

We can not use chemical herbicides in my community. I have 2 x 50 foot rows of table grapes. I am laying down black landscape fabric to help with weed/grass control and have 2 questions.

1) All grapes are planted in 3 food diameter mounds that were dug down 3 feet with the clay edges well scored. I was thinking that since I am laying down the fabric, what about laying down a raised mound the entire length of the row to give some roots a chance to grow above the wet area in the spring and fall. Is this a good idea? What sort of soil should I use - 3:1 planting soil for trees, compost, plain old garden soil? I was planning on just dumping it over the existing grass and covering with the landscape fabric and allow the worms to incorporate. Should I rototill to break up the grass and disrupt the clay/surface dirt transition or can I just let humidity and the worms take care of it?

2) What should I put (if anything) on top of the landscape fabric? I think it should be covered at least during winter to improve survivability and attempt to delay bud break for late frosts in the spring (that black will heat up fast). But then I might want the black exposed for our short growing season to give a heat boost for the vines. What do you think? Hay for the winter and remove in spring. Bark multch year round? other?

Thanks for your help.

Warming the soil some is a good idea. I like the hay in winter bare in summer. Just be sure you aren't making a home for voles or mice. Either could live under fabric or hay and chew on the vines.