I live in King City Ontario North of Vaughan.
I am interested in knowing about this every green I have seen growing on step like structures.
It appeals to me as it appears to cover areas without giving room for weeds and it is green through the year.
The plant in your picture looks like it might be a form of juniper (juniperus). The most commonly used prostrate juniper is Juniperus horizontalis (or Creeping Juniper) which is native to North American. It is very hardy, does not suffer from either the heat or the cold and will grow in a variety of soils. Creeping Juniper thrives in the sun but will tolerate some shade. It is best where there is good drainage. There are many varieties from which to chose, including ‘Wiltonia’. Other horizontal junipers which you might consider include Juniperus communis ‘Green Carpet’, Juniperus conferta ‘Blue Lagoon’, Juniper x pfitzeriana ‘Aurea, Juniperus procumbens ‘Nana’, Juniperus squamata ‘Blue Carpet’. I suggest that you check out a nursery, or a botanical garden, which has a number of junipers, to determine which you would like to try as there is wide variation in colour and form. Note that some junipers have fairly consistent colour throughout the year; other may change colour (although they do not loose their needles) during the winter.
Note as well that while junipers are generally very attractive when young; they may suffer from die-back as they mature. Some varieties also benefit from pruning when young to encourage density and if appropriate restrict spread.