Roof greening should choose plants with not particularly developed roots and good cold tolerance.
For example:
(wood) a low pile of bonsai of pomegranate, pine and cypress.
(perennial herbs) Ophiopogon japonicus, Iris, Paederia, Phytolacca acinosa, Asparagus, Trifolium repens, Oxalis purpurea, etc.
(annual and biennial herbs) colorful grass, purslane, zinnia, kale, Kochia scoparia, jasmine, Petunia, February orchid, etc.