I have a 8m x 3m bed in my garden which has a mix of well-established shrubs (Weigela, ornamental cherry, smoke bush, roses), ground cover (ivy and honeysuckle), and red valerian, lemon balm and lungwort.
I recently dug up a snowberry to replace it with a hydrangea, and found that the bed is actually about 20cm of gravel with two layers of weed membrane under it. It has obviously been there a long time as enough leaf litter and detritus has built up to turn the gravel into poor soil, into which the valerian and the other smaller plants are rooting. The weed membrane is largely intact and is blocking the roots from spreading into the soil below.
I'd like to clear some of the ivy and try planting some other plants in there. My aim is to slowly move towards permaculture/forest gardening ideas, growing more edible plants.
But all the roots tangled up in it mean removing the gravel and membrane is extremely difficult (apart from the intrinsic difficulty of shifting large volumes of gravel!) The soil under the membrane is well-compacted clay with apparently little organic matter.
Any ideas how to deal with this situation? I had thought of putting a fork down through the membrane to open up some holes and then just planting in the gravel, but it would be pretty poor soil. Should I focus on improving the gravel and leaving the membrane alone?