It's impossible to have too many dwarf ginkgos in an urban garden. They work as small punctuation marks, as great contrasts in foliage and are extremely adaptable. I'm up to seven in my own garden – this is not to be competitive (imagine, a competitive gardener!) but to prove that they can be tucked into small gardens and not be too overwhelming.
These dwarf plants, however, have to be watched very carefully. The parents of the cultivars are inclined to be very large, and if a shoot starts growing below the cultivar's graft, you'll end up with an enormous tree: Regular varieties of Ginkgo biloba can hit up to 17 metres. If you love this species you have to be sure it's a male form – the female in season stinks outrageously. Planting a nice unstinky male is very important.
What started my fascination with ginkgos was the cover of Irving Penn's 1991 book of photography. It featured close-ups of the ginkgo leaf, and I couldn't stare at it enough. It opened my eyes to the need to examine leaves minutely in an attempt to understand the astounding intricacies nature presents us.
This most ancient of trees was once a native of North America but now, millions of years later, their origin is Asia. It's a great street tree because it puts up with the pollution and filth with which we garnish our cities. But the babies, the dwarf cultivars, are the best of all plants for containers, patios, terraces. They tuck in magnificently among other pots or in the ground as standards.
'Mariken' (Zone 5) has leaves that fan out in the most graceful manner, creating layers down the stem. In spring, they start out pale green then turn into a deep green and eventually into the staggering gold of autumn. Even the shape in winter has a winsome quality. It isn't perfectly rounded, and that irregularity is part of its charm.
Ginkgos put up with many different conditions: wet, dry, sun, shade. Maybe it's their great age as evolving gymnosperms, maybe it's clever cultivation. Plant them in good soil with lots of organic matter (compost) and mulch deeply without touching the main trunk. Water deeply, then do it again in a few days. Once you see new growth, water only when needed. That is, the soil around the base will be pretty dry.
No matter what ginkgo cultivar you buy, it's going to bring you years of pleasure, so site it properly; add other ancient plants such as ferns. I have mine near Athyrium 'Ghost' and a hellebore that has been blooming for weeks. This is the thrill of the late summer garden: new pleasures and surprises.
Find Ginkgo biloba 'Mariken' at garden centres including Rideau Woodland Ramble in North Grenville, Ont. (www.rideauwoodlandramble.com), where a one-metre-high plant retails for $160 (smaller, more shrubby forms from $55).