Here’s a little trick I employ when the holes in the bottom of a container are too big to hold the soil in at planting time.
I just rip a single sheet of newspaper to the approximate size of the bottom of the pot and place it in the bottom before adding soil. In the case of single hole pots, I rip a piece that is only a few inches larger than the hole; no need to cover the entire pot bottom.
Years back, I used to search high and low for shards of broken pot to cover over the hole, but newspaper is abundant and will eventually decompose. Drainage is not obstructed if you used a single sheet and you’ll never have to think about it again.