Scilla peruviana planting depth?

[kGarden]

I have some Scilla peruviana to plant and sites are divided on planting either "tend to grow naturally just above the soil so when planting, leave the tip showing" and "Plant 4" / 10cm deep"

These will be planted out. not in containers.  Heavy clay here, so I plan to plant with plenty of drainage material. I would appreciate your advice on both depth and any suggestions on for soil improvement etc.

[Karaba]

Depth depends on what you look : tip at ground level, base at 10 cm deep  You can plant a little deeper with the tip at 10 cm deep, I never see much difference but I've never actually it in heavy clay...Usually and finally, bulbs "choose" they deepth and they often give more bulbils when they are not deep.
Scilla peruviana is quite hardy but need to rest at dry during summer. They should be plant early since they do leaves in autumn.