All my fruit trees and berry bushes are planted into grass, in rows. I mow around each plant. Of course I can't get right up to them, and whether you mow or not, they are still having to compete with the grass.

There are good sides to growing them in grass, and downsides. When I see people's fruit trees that are grown in tilled soil, they get much bigger, much faster. I'm sure they are able to produce more as well..because all the nutrients and water is for them alone. One plus side of having them in grass, is that because the grass steals some of the water, my plants "go to bed" quite nicely in fall. I don't get die-back, because they don't get an excessive amount of water (leading to new growth) too late in the year.

I do provide some supplementary watering in the summer, particularly when the fruit is setting and when the fruit is swelling. I don't water haskap's while they are fruiting, because we've had enough moisture during the years I've had them. I do water them alongside everything else, though, during the hottest time in summer. Maybe it will help them grow faster.

I wouldn't mind tilling a tiller width around the bush but wonder how close I can get without damaging the roots?

I wonder if those weed barrier matts compress the soil?

I'm not sure about the tilling. I've always thought it would disturb their roots..maybe you have to plant into prepared, tilled soil, and then you just till very shallowly or something?