Yes, you can grow elderberries in a compact space and the roots will most likely not disturb the asphalt - but it does depend on what type of soil you have and how deep the roots go to get water. If you water less often but deeply (once a week instead of every few days) the roots will be encouraged to grow deep. Do you want to grow the plants for berries or are you thinking of the ornamental Black Lace elderberry with purple leaves and pink flowers? You may want to think about placing large pots or tubs in the space and grow the plants in containers if your soil is clay or compacted. Keep growing, Marianne Binetti