The buried pipe is in no way going to help the plants . You need to ammend the soil I use peat moss, sand and steer manure in equal parts for each hole I dig for planting make the hole at lease twice as big as the container the plant comes in and 3 x is even better make sure that the hole with ammendments is 2x deep than needed This has always worked for me in clay soil. If you have the time and not planting until next year a good crop of potatoes does a good just of breaking up clay

Regrettably, I have become an expert at this. I like to double dig and get down about 18”. I remove all rocks and often lumps of solid clay (it’s so bad where we live I could throw pots). I mix in peat and rotted manure, to at least equal the soil. You can also use compost, worm castings, pine straw, rotted seaweed, leaf mold - basically anything organic.

I work in patches about 2’ by 2’. You will need a pick axe and a shovel. A sifter is good for removing small stones. It is backbreaking work, but the results are phenomenal.

Remember with bulbs, the bottom cannot be on the clay, because the roots need to be in good, well draining soil. Adjust the pH according to what you want to grow. Add Hollytone for azaleas, boxwood and the like.

Interesting about the potatoes! I have started using expanded clay pellets and/or red lava rock in areas where I have that uber-dense clay,to help aereate it. I found that only using organic matter and peat didn't work, because once they rotted away I was back where I started. So my new recipe is organic matter and expanded clay.