Experts and BHG readers answer.
in-ground pool to garden conversion
It's a good idea to puncture the liner of the pool before filling the pool with soil. Otherwise, water can collect in the old pool, and roots will rot. Generally, it's not necessary to completely remove the pool liner because water will collect at the bottom of the liner, and gradually drain out the punctures or holes that you make. Most of the roots of annual and perennial flowers will be in the top foot or so of soil, so they'll be relatively unaffected by temporary high moisture levels. You likely will want to "overfill" the pool with soil, creating a bit of a raised bed to start with. Over time, the soil will settle and compact, so if the soil isn't mounded a bit initially, you'll end up with a sunken garden in a few years.