My wild grape vines love growing up trees, and are probably planted there by birds roosting in those trees. In my little apple trees' second year I already had to remove grapevines that were climbing them! I planted some garlic around the trees which did OK, and tried some lentils which never grew. For growing grapes in cultivation I've never discovered a good companion that kept grass out. Grass is definitely bad, as it is for many fruits and veggies. Clover is good but grass always seems to get into it here. Grass gets everywhere there is not full-day dense shade, and even gets into some shaded areas.
Kiwi(fruit) doesn't grow in my zone 6, but Hardy Kiwi certainly does! Mine followed the "first year sleep, second year creep, third year leap" adage. Now it is trying to take over my entire deck: trellis, railing, gate, stairs, rain barrel, and over top of the roof as well as around the support posts! I had to cut free a rarely used deck chair and table that had been partially engulfed last year. Luckily for those vines, the fruit is absolutely delicious, like large kiwi-flavored green grapes. I planted nothing around them, just replaced the stone "mulch" that was already there before the deck was built. I've never fertilized them, and after the first year they've only been watered by the rain. I may have to cut them back to just a couple feet off the ground since the vines are thickening and busting apart my wood lattice trellis. They'll grow back quickly, I have no doubt!