Traditional Gardenia for Fragrance Gardens

Gardenia jasminoides (pronounced gar-DEE-nee-ah jaz-min-OY-deez) was previously known as Gardenia augusta. Native to Asia, it is one of the south’s classic shrubs. Gardenia shrubs thrive in heat and humidity, and require acidic soil. We have all three! They have a long flowering period, with single or double flowers than range from white to cream to almost-yellow.

Plant new Gardenias in spring so they will be well-established before the onset of cold weather. They prefer moist soil with plentiful organic matter, and partial or dappled shade, zones 7-11. Mature plants may reach heights up to eight feet. Several shorter cultivars are available, as well as some (‘Kleim’s Hardy’ and ‘Frostproof’ are two) that are more cold-hardy.  Gardenia’s shallow roots dislike disturbance. Locate them away from trees or areas with strong winds. Avoid planting them next to concrete driveways or sidewalks that may leach lime into the soil. Use an acid-based fertilizer specifically formulated for Gardenias or Azaleas. Prune Gardenias in late winter or early spring to remove any dead or damaged branches. This will encourage new growth and keep the plant looking healthy.

Gardenias can be used as an evergreen hedge or as specimens in fragrance gardens or moonlight gardens. While their glossy leaves and sweet-smelling flowers can make them the star of summer garden tours, spent blooms fall to the ground and can look messy. Remove them for the neatest appearance.

Despite their heavenly fragrance, Gardenia does not make an ideal cut flower. Flowers react poorly to the touch of human skin, and their pristine white petals take on the yellow tint of old mayonnaise. If you choose to use them as cut flowers, take care to avoid contact between skin and flower petals.

Gardenias are susceptible to a number of pests and diseases, including scale insects, whitefly, mites, and root rot. Sooty mold is a frequent problem. Keep an eye out for any signs of infestation and treat promptly to keep your gardenia healthy. They are prone to damage by deer. While Gardenia can be grown as a houseplant, whitefly is a common problem.

Calycanthus, Carolina Allspice or Sweetshrub

Sweet Shrub is a homely shrub with a heavenly scent. Native to the southeast, Sweet Shrub grows in part shade. It will reach heights of six to ten feet, and spreads indefinitely by suckering. Flowers of the species are nondescript, wine colored, and easy to overlook. Newer cultivars have larger, more attractive flowers but may not be as fragrant as the older type. The flowers have a scent that is described as a cross between strawberry and kiwi. Bruised foliage has a pleasant scent also.

Sweet Shrub (Calycanthus floridus, pronounced kal-ee-KAN-thus FLOR-id-us) is perennial in zones 4-9. It will reach heights up to 12 feet in clay or loamy soil with an acidic or neutral pH. Flowers have strap-like petals (tepals) in shades of burgundy to brown. Newer cultivar ‘Athens’ has white flowers and ‘Aphrodite’ has a brighter red bloom than the straight species. ‘Hartlage Wine’ has larger, showier flowers.

Locate Sweet Shrub in a woodland garden to seating or pathways so that its fragrance can be enjoyed. Flowers are popular with pollinators and shrubs are usually ignored by deer.

This is the native version of Calycanthus, Sweet Shrub. Newer cultivars have larger flowers. Reports indicate that newer cultivar ‘Venus’ is equally fragrant.

Winter Daphne for Cool Weather Fragrance

The rest of the US is facing a wave of frigid weather, but in the deep south, warm temperatures have brought gardeners outdoors, where we are enjoying the scents and sights of Forsythia and all the sprig-flowering bulbs. The sweet scent of Daphne wafts over it all.

Daphne odora (pronounced DAF-nee oh-DOH-rah) or Winter Daphne is an evergreen shrub that grows to heights up to six feet in zones 7-9. In late winter, its rose and white flowers have a heavenly fragrance that makes gardeners forgive its propensity to die suddenly, without warning (known as the “Daphne Death Dance” among gardeners who have loved and lost it). Plant it in partial shade in moist, neutral pH soil that is very well drained and has plenty of organic matter. It lives longest when sited on a slope that ensures good drainage. It also does well in a container if sited in a protected area. ‘Aureo-marginata’ is a variegated form. Prune leggy plants after flowering is complete to keep them compact and attractive.

All parts of the plant are poisonous to humans

Daphne odora in bloom. Special thanks for this image to shell_ghostcage via Pixabay photosharing.

Mock Orange

Mock Orange, Philadelphus coronarius (pronounced fill-uh-DELL-fus core-uh-NAIR-ee-us), is a deciduous shrub grown for its sweet scent. When not it bloom, it is rather homely. Its stems are stiffly upright or occasionally, arching. Mature size is ten feet tall, eight feet wide. With time, the shrub becomes dense and twiggy. Flowering is on previous year’s limbs, so prune selected stems off near ground level immediately after flowering to force new growth for the following year. The bloom season occurs in May or June, and lasts several weeks.

Mock Orange is hardy in zones 4-8. It prefers full sun to part shade, and moist, well-drained soil, although it is somewhat adaptable. It prefers neutral to alkaline soil. Established plants withstand limited drought. Its white flowers make Mock Orange an ideal selection for a moonlight garden, where its intoxicating scent compensates for its unremarkable appearance. Fragrance is more pronounced in the evening.

Mock Orange is easily propagated from stem cuttings. Plants are somewhat deer resistant.

Philadephus coronarius has pure white, fragrant flowers.

The shrub has arching stems. Left to its on devices, it can become ungainly.

Note: A sharp-eyed reader noticed a mistake in last week’s blog. Amsonia hubrechtii is native to Arkansas, not Arizona. My secret is revealed — I easily confuse state abbreviations. Thanks for the correction, Gentle Reader!

Pretty Pittosporum Shrubs

We have had some trees removed to open up a mountain view. As a result, there is a new design opportunity in the Mary Snoddy garden. The steeply sloped area, approximately four acres, has scattered tall hardwoods, a few native Dogwoods, patches of Mountain Laurel, numerous Sourwood trees, and rocks for days. Big rocks. My vision for the future includes a meandering  path with decorative plantings on either side, all the way down to the creek. The path will need switchbacks due to the steep slope. Opportunities abound for plants in full sun, full shade, and everything between.

My tree and shrub choices need to be hardy in zone 7 with a tolerance for rocky, acidic soil.  They also need to be tolerant of heat and humidity while being deer resistant (a relative term, for sure). I started my plant selection Wish List by scanning photos of other gardens I have visited and admired. From this, I gleaned a small set of shrubs and trees to research. One of these is Pittosporum tobira ‘Variegata.’ I can still remember the wonderful fragrance of this evergreen shrub, a variegated cultivar clad in gray-green leaves with white margins. The clusters of flowers open white but turn yellow when pollinated. The homeowner had allowed the shrub to grown unpruned. It was four feet tall and about the same width.

I learned several things about Pittosporum. First, I have been pronouncing the name incorrectly for decades. It’s not pit-oh-SPORE-um. The correct pronunciation is pih-TOSS-pur-um. It is cold hardy in zones 8-10, although cultivar ‘Mojo’ is more compact and a bit more cold-tolerant. ‘Wheeler’s Dwarf’ is even more compact but less cold-tolerant than others. Mature height for most cultivars is 8-10 feet.

Pittosporum is tough, fast-growing, demands well-drained soil, and makes a good evergreen hedge. It is not particularly choosy about light (full sun to partial shade) or soil acidity. It is resistant to salt, making it a good choice for coastal gardens.

Unfortunately, deer are attracted to Pittosporum and frequently browse it year-round. This trait and its borderline hardiness in my area moved it from my ‘Wish’ list to the ‘Not For Me’ list.

Pittosporum has an interesting characteristic known as ‘sympodial growth.’ This means that the terminal bud will stop growing and lateral buds will keep on growing, giving stems a zig-zag look. This constant forking is also seen in some orchids and Beech (Fagus) trees. For Pittosporum, the terminal bud usually ceases growth because a flower has formed at the tip.

To prevent leaf spots and fungus problems, provide good air circulation, avoid overhead watering, and remove fallen leaves. Note that Daconil®, a common fungicide, is not labeled for use on Pittosporum and will damage or kill the plant. Counter aphid attacks with spray-on horticultural oil.

Pittosporums are easy to propagate from cuttings taken in late summer. Use a talc-based rooting compound to increase success rate.

Clemson University has an excellent fact sheet: https://hgic.clemson.edu/factsheet/pittosporum/

Pittosporum in flower.

Photo by Jean-Pol GRANDMONT - Own work, CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=4561211