Hi Marley, I agree that trellis is your best bet. You could create a narrow border along the bottom of the wall by removing the turf, add some compost to bring the level of the earth up then plant climbers dotted along your border. Try things like clematis, honeysuckle, Russian vine, Virginia creeper these are all fast growing but will still take a few years to establish. Meanwhile try growing sweerpeas, climbing nasturtium, black eyed Susan etc and maybe even some runnerbeans these will cover the trellis this summer if you get plug plants in the ground now. Hope that helps x