Question
how deep do you plant bulbs such as lily, glads, sedum and sundrops?

Answer
Hi Carol,
A rule of thumb for any bulb is go 3X as deep as the bulb.  If the bulb is 3 inches in depth, plant the bulb 9 inches deep.  Glads though, are corms and much flatter than a bulb, I would go ahead and plant them at 6 inches because they have a tendency to blow over in the wind if planted too shallow.  With any plant like sedum?  I just make sure the planting hole is a little larger and deeper than the potted plant or the root ball so that it sits comfortably and not crowded in the hole and is sufficiently covered by earth.  I hope this helps.
Tom