Joe’s Journal, Summer Edition: The Fragrant Garden

Landscape garden design involves three elements: form (size, texture), color, and fragrance.  Flowering trees, shrubs, and vines waft fragrant and sometimes transcendent olfactory aromatics right at your doorstep, with just a bit of planning.  In this installment, let’s consider a selection of shrubs you might plant for their aromas when in flower.  If planned well, you can have fragrant blooms from early spring through late summer.  The group of plants include Carolina allspice, the viburnums, the common lilac, sweet pepper bush, and roses.

Early Spring Flowering

Calycanthus floridus (Carolina allspice) is an erect to rounded deciduous native shrub in the Calycanthaceae.  It is found in the southeast, growing in shady woodlands and along streambanks.  It grows 6-12′ tall with an equal or slightly greater spread.  It is commonly called sweetshrub and strawberry bush in reference to the showy red-burgundy fragrant blooms which have been described as combining hints of pineapple, strawberry, and banana. It is best to purchase the plant in flower as the fragrances do vary widely.

Sweetshrub grows best in average to rich, well-drained soil in full sun to deep shade.  It prefers some shade in hot summer afternoons and grows lankier and less dense in shade.  It is tolerant of a wide range of soil textures and pH but prefers rich loams.  Amend soils with a good organic matter, such as compost made from leaves.  Plant it 3 to 5 feet from other shrubs to give it adequate room to grow.  It blooms several times: in early spring before leaves emerge, with the leaves, and sporadically thereafter.

Prune immediately after flowering to maintain compactness.  It has a suckering habit, meaning those suckering branches need to be pruned off unless you want the plant to naturalize in your landscape.  Note that next season’s flowers are produced on new and old wood.

Carolina allspice can tolerate brief periods of flooding, but does not do well in sandy soil and drought conditions.  It withstands cold and heat, insect and disease pests, fire, and deer browsing.  Plant it as a specimen or near a patio or walkway to enjoy its fragrance.  Its form makes for a good screen or privacy hedge, or plant it in a foundation planting.  Consider planting in your cutting, sensory, or woodland garden.

Spring Flowering

Viburnum carlesii (Korean spice viburnum), V. x burkwoodii (Burkwood viburnum), V. carlcephalum (Fragrant viburnum) and V. x juddii (Judd viburnum) all are great choices for early spring fragrance.

Korean spice viburnum prefers sun to partial shade and moist, well-drained soil.  It has a rounded, irregular dense form with stiff upright branches.  The blooms are showy and fragrant.  It flowers on old wood, so prune immediately after flowering.  Use as a hedge, in shrub borders, or as a foundation plant. Very fragrant flowers appear in mid to late spring.  Fall leaf color is reddish-burgundy.

Burkwood viburnum is an easy-to-grow shrub that has showy fragrant flowers attractive to wildlife.  It is a cross between V. carlesii and V. utile, grown for its early, strongly scented flowers.  This particular hybrid is not as showy as others with its summer fruit display.  To have the best cross-pollination and fruit display plant in groups rather than as specimens.  It is adaptable to a wide range of soils and pH types.  Mature plants have excellent heat and drought tolerance.  Leaves turn maroon in fall but remain evergreen in zones 7 and 8.  Use as a foundation plant, hedge, or specimen in average moist garden soil in full sun to partial shade.

Fragrant Viburnum is a deciduous shrub that is easily grown in average to moist well-drained soils with good drought tolerance once established.  It is a cross between V. carlesii and V. macrocephalum and grows 6-10 feet tall and wide.  It grows as a multistemmed shrub with an open and rounded form.  Fragrant Viburnum produces fragrant snow-ball type blooms in the spring and has reddish fall color.  For best fruit production plant in groups.  Use as a foundation plant in shrub borders or as a hedge.

Judd Viburnum is a hybrid cross of V. carlesii x V. bitchiuense introduced in 1920.  It grows 6-8 feet tall and wide with an upright rounded shape. The pink buds open to snowball clusters of fragrant white blooms in spring.  The fall color is purple-red. It is adaptable to various soil types and is drought tolerant once established.  It attracts birds and pollinators.  Use this shrub as a screen, hedge, in the border or as a specimen plant.

Mid-to-Late Spring Bloom

Syringa vulgaris (common lilac) is a highly fragrant, spring-flowering shrub or small tree.  There are hundreds of cultivars available including single and double flowers, and various colors such as white, cream, rose, magenta, pinkish-purple, lavender, and purple.  The pungently sweet fragrance is delightful but can be overpowering to some.

Most plants are grafted, so suckers should be removed from rootstock to maintain the appearance and prevent unwanted spread.  This plant grows rapidly to fill its space.  It makes excellent cut flowers after its spectacular mid to late spring bloom.  The shrub is of little interest in the landscape with its leggy branches, so is best planted in a mixed border rather than as a specimen plant.  The leaves are susceptible to powdery mildew.

Lilac does best in cold winter climates as they require a long period of winter chill for the buds to mature. Late frost will sometimes kill the buds, so it is best sited in a protected location.  It is tolerant of different soil types but does not do well in soil that is highly acidic or poorly drained.

Summer Bloomers

Rosa spp. (roses), once common have fallen from favor on account of their susceptibility to fungal diseases, particularly powdery mildew and black spot, and to insects such as Japanese Beetles.  You may consider Rosa rugosa, a hardy and disease resistant shrub rose if you want roses in your fragrance garden.  Rosa Rugosa is the original wild Rugosa from Japan.  It is a vigorous, easy-to-grow bush that thrives in poor conditions, even at the seashore.  It has blooms of reddish-purple that are followed by large, edible hips high in vitamin C.  The rugose rose has a great, strong fragrance and is a repeat bloomer. One of the hardiest roses available, it thrives in zones 2-9.

Fragrant roses come in a number of forms and colors.  Colors virtually run across the spectrum from red to violet.  You can select the fragrance most attractive to you as well. Some standouts are:

• ‘Madame Anisette’, a shrub rose with cream-colored blooms has an extraordinary scent.  As her name suggests, Mdme. Anisette smells of licorice with hints of aromatic-woody myrrh, spice, and notes of honey.
• ‘Don Juan’, a climbing rose, produces scores of large, dark velvet-red blooms. Don Juan has a tea or fruity fragrance and is easily one of the finest of the red climbers.
• ‘Lady Ashe’ is a very disease-resistant, hardy climber that can also be grown as a shrub. It has a strong fragrance and blooms in subtle shades of peach pink and apricot. Lady Ashe does well in gardens in zones 5-10.
• ‘Black Lady’ is dark red and is strongly fragrant. Black Lady blooms in flushes continually throughout the season producing medium and double blooms, a stand out in the garden and best in zones 6-10.
• ‘Scent-sation’ is one of the most fragrant hybrid tea roses, with orange and peach petals.  Blossoms form singularly, or occasionally together, on a continual blooming, vigorous plant.
• ‘Belle Amour’ is a coral pink flower, unique among old roses.  Its slightly cupped, semi-double flowers with golden-yellow stamens are borne in clusters on a vigorous, upright shrub.  The flowers have a strong myrrh fragrance.  It is a very old variety discovered in a French convent.

The Late (Summer) Bloomer!

Clethra alnifolia (Sweet pepperbush) is a deciduous shrub in the Clethraceae family.  It may grow to 5 to 10 feet and often spreads into mounded clumps.  It is native to eastern North America from Maine south to Florida and west to Texas.  In the wild, it is often found in swamps, damp thickets, and sandy woods.

The leaves are alternate with a finely toothed margin.  The bark is gray and loosely striped.  Small, white flowers occurring in dense clusters on long 3-to-6-inch terminal spikes that mature in late summer.  The variety ‘Ruby Spice’ produces fragrant, rose-pink flowers.  The flowers produce high quality nectar and pollen that supports hummingbirds, butterflies, bees and other pollinators.  The shrub produces a brown, dry capsule that matures in the fall and provides seed to birds during the winter.  Sweet pepperbush is unique among flowering shrubs because it blooms in shady locations in late summer when few other shrubs are in bloom.

This shrub is often grown as a screen, or as a specimen, or in groupings as a border.  It prefers moist, acidic soil with ample organic matter.  It tolerates short periods of drought and flooding once established.  It grows in full sun to partial shade, but will not tolerate a hot, dry site.  Plants are hardy to about -22 degrees F (USDA zone 4b).  When grown in conditions similar to its native habitat, it will produce suckers and eventually form small thickets.  However, it responds well to pruning, which is best done in winter or spring.  Sweet pepperbush flowers on current season wood (that is, on new growth).

In our next blog, we’ll consider the sequential seasonal flowering of perennials, shrubs and vines in our landscape garden.  The order of flowering does indeed matter!

~ Singing off for now, Joe