Wednesday, September 28, 2011

The Best Trees for Small Gardens; Fall Color

The fall colors of the sweetgum tree last for many weeks.

Walking through an arboretum at this time of year is a true feast for the senses. Fiery shades of red, orange and gold burn against the watery blue sky, Katsura trees (Cercidiphyllum sp.) release their tempting candy apple aroma, shiny brown ‘conkers’ from horse chestnut trees (Aesculus sp.) are waiting to be scavenged by children while crisp leaves scrunch underfoot, just begging to be kicked into the air.

These autumnal scenes may be on a large scale yet they can also be our inspiration for making the most of the season in smaller gardens. Not everyone has room for a spreading English oak tree or a large grove of aspens, but there are some great trees of a smaller stature which offer just as much vibrancy as their larger cousins.

Without a doubt Japanese maples immediately come to mind when considering fall color and there are some wonderful books to help you select the best ones for your situation.  My personal favorite is Japanese Maples by J. D. Vertrees or its companion pocket guide which I find invaluable for nursery visits. However, in this post I’d like to focus on the underused and lesser known fall beauties.

The rich colors of Persian ironwood.

Persian ironwood ‘Ruby vase’ (Parrotia persica) is a new addition to my garden and I’m already thrilled with it. It has a strong, upright vase shaped habit with attractive exfoliating grey and tan bark that promises an interesting winter silhouette. Purplish-red new foliage becomes green in summer turning fiery shades of orange and mahogany in fall. In late winter to early spring a profusion of small red flowers appear making this a great year round specimen. At only 12’ wide it can fit into smaller gardens, yet its 30’ ultimate height gives a sense of age and stature amidst the more typical shrubs and smaller trees. ‘Vanessa’ is another excellent variety.  Persian ironwood needs full sun for best color and is hardy to -10’. 

October foliage of the sourwood tree.
My photo

Sourwood (Oxydendrum arboreum) has long been a favorite of mine - and of the hummingbirds. The pendulous racemes of fragrant white flower appear in July and last all winter, making a striking contrast with the scarlet fall leaves. I have underplanted this with ‘Peach flambĂ©’ Heuchera and geranium ‘Biokovo’ to make an attractive year round vignette. Typically  this grows to 25’ tall and 15-20’ wide.

Sweetgum (Liquidambar styraciflua) has joined me in several gardens now. Like the Persian ironwood it offers good height while keeping to a modest footprint. I have used it to provide screening by allowing the canopy to develop above a fence line, and also amongst a mixed conifer border where it provides a change of pace with its corky bark and tidy vase shape. Fall colors include purple, burgundy and orange while the leaves seem to stay on the tree for a long time. ‘Slender silhouette’ is especially suitable for smaller gardens at 6-10’ wide.

Bathed in the golden light of the ash tree, the color of
the smoke bush is intensified.
My photo

Ash trees (Fraxinus sp.) may not be the first choice for a small garden and perhaps be considered too ‘ordinary’ by the tree connoisseur, yet their rich yellow foliage in autumn is hard to beat. It makes for a memorable combination with ‘Grace’ smoke bush (Cotinus coggygria) and when backlit the golden glow is breathtaking. In summer we set our table and chairs under its whispering canopy where it provided dappled shade – much more inviting than a patio umbrella. The variety ‘Summit’ (Fraxinus pennsylvanica) is narrower than most at just 25’ wide while its 45’ height marks it as a significant tree. Hardy to zone 3. 

Fragrant summer flowers are just
one of the reasons to grow
the Franklin tree.
Photo credit; Michael Dirr

It’s a shame that the Franklin tree (Franklinia alatamaha) is not more widely grown. Ideally suitable for small gardens growing to just 20’ tall and 6-15’ wide, it offers large fragrant flowers in July/August and has an interesting smooth grey bark, broken by irregular vertical fissures. The long lustrous dark green leaves turn shades of purple and red in autumn. Use this as a specimen, accent or incorporate into mixed borders.

Columnar trees are invaluable for tight spaces especially narrow side gardens. The columnar European hornbeam (Carpinus betulus fastigiata) and ‘Amanogowa’ cherry tree (Prunus serrulata) are two reliable performers which turn vivid yellow and red respectively, while the cherry tree is also a springtime favorite when smothered in soft pink blooms.

I invite you to re-examine your garden with new eyes. Are there layers of fall color or is the primary interest restricted to smaller shrubs and a dwarf Japanese maple? Consider extending the display vertically by the addition of one or more of these exceptional small trees. Just because your garden is small doesn’t mean you can’t go UP.

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