Marco van Noort named Sweet Heidy for his wife. All those plant introductions, all that labor, and this is the one he’s chosen to give his wife’s name to! This alone tells us how special Sweet Heidy is.
The biggest distinction between Sweet Heidy and Orkney Cherry, aside from the foliage and bloom colour, is the habit. Sweet Heidy is partly trailing, a good plant for hanging baskets, flower pots, low walls, terrace gardens, that sort of thing. Give it a place to trail and it will do so, stretching about 2 1/2 feet long if need be. Simply lovely, needless to add.
Orkney Cherry is a spreader, and for a Geranium, it wastes no time! Give it bare soil and it will grow a 2 foot mat of fairly dense (this is a Geranium after all, not a creeping Phlox!) foliage of absolutely beautiful green spotted and veined faintly in deep pink, the same colour as the blooms. It’s a good choice for the border, because while it’s aggressive, it won’t choke anything out or really get in the way.
That said, most people will prefer Orkney Cherry because it’s the heaviest-blooming Geranium I’ve ever seen, full stop. The bloom season is endless too, but Sweet Heidy has an extra long season as well. For sheer number of flowers in a season, there’s no beating Orkney Cherry.
To give Sweet Heidy its due, the flower colour is its remarkable (and unique) merit. The flowers emerge a sort of cream colour with infusions of pink, which darkens as they mature. Finally they acquire blue edges, whilst keeping the pink further in, and the cream around the base. It’s the only hardy Geranium I know with this multi-ringed look. I hesitate to call it tri-coloured because all the shades aren’t present throughout the life of the bloom, but it is really distinctive and rather amazing.