I have just planted three Rheum rhabarbarum‘Victoria,’ a Rhubarb variety known for its sweet tender stalks, and not generally known as a green roof plant.    I am optimistic.   They now inhabit the center of the blackberry/raspberry patch, with deep humus-rich soil and partial shade, which they prefer.   Like so much in horticulture, Rhubarb requires patience.  I will not be able to begin harvesting stalks until 2014.   (A reminder for readers who may be inspired to do the same, the leaves of Rhubarb, with heavy concentrations of oxalic acid, can be toxic when eaten in large quantities and are best avoided.)

Just opposite the blackberry/raspberry patch, the blueberries survived the harsh winter with aplomb, and show all signs of a bumper crop to follow:

And just down the central axis in the orchard, the nectarine tree continues its precocious ways:

Finally, a roof-top garden inevitably triggers meditation on the interface between the built and natural environments.   Is this a foreshadowing of the natural world asserting dominion following the decline of civilization (think the last two pictures in Cole’s Course of Empire), or a herald of a brighter age when man and nature reach a happy accommodation: