By Molly Day
All the Dirt on Gardening
Gardenias, also called Cape jasmine, are best known for their sweetly scented waxy flowers and thick, shiny leaves. Most of us associate them with warm climates because out of the 200 species, only a few are cold hardy enough to grow in our area.
The flowers vary but tend to be 2 to 4 inches across with six or seven wedge-shaped petals. The fruit that follows is an inch long and matures into a deep orange color in late fall or early winter. If the seeds are harvested they can be planted to grow more shrubs.
Their native growing areas are the open woodlands and savannahs of Africa and tropical Asia where they retain their leaves all year and grow into 6-foot tall woody plants. The first American imports from Asia arrived in 1761. They were cultivated by John Ellis on his South Carolina plantation where he named them for his friend Dr. Alexander Garden.
New varieties are cold hardy in our zone 7 and gardeners as far north as Canada have been successful with garden planted specimens. If you plant a Gardenia in a pot, you can move it around until you find its ideal location and then put it in the ground.
Gardenias like similar growing conditions to camellias and azaleas: Slightly acidic soil, protection from strong wind, spring and summer feeding with azalea-camellia food, protection from strong afternoon sun, acidic mulch and consistent moisture but never soaking wet roots. Sandy soil and clay soil will have to be amended with compost to provide enough nutrients and good drainage.
Planting idea: Place gardenias in the same bed with other tropical looking plants like hibiscus, elephant ears and lantana.
The scent of gardenia’s flowers will make you want to put them close to an entrance or window where they can be enjoyed. A large container could be planted with a combination of scented plants such as lavender, sage and jasmine on a trellis.
Gardenias are considered deer and rabbit proof due to their thick leaves.
Michael Dirr, author of “Dirr’s Encyclopedia of Trees and Shrubs” has been breeding cold-hardy gardenias at the University of Georgia. He recommends the varieties that he worked on: Heaven Scent, Madga 1 and Pinwheel for their cold-hardiness, orange fruit, compactness and re-blooming qualities.
Walter Reeves (walterreeves.com) recommends Gardenia jasminoides “Grif’s Select” that grows only 3 to 4 feet tall and has lots of red seed capsules in the fall.
Shopping tip: Gardenia jaminoides, Gardenia augusta and Cape jasmine are the same thing.
Kleim’s hardy, developed by J.C. Raulston in North Carolina is now available from ball ornamentals; it can take temperatures plunging to zero. One online catalog lists them as cold hardy to USDA zone 5 though most say only to zone 7 or 8.
Frostproof gardenia, Gardenia jasminoides “Frostproof,” slowly grows 4 feet tall and has heavily-scented, double white flowers. It is cold-hardy to zone 6.
Logee’s offers frostproof and gardenia species plants by mail at www.logees.com.
Gardenia “Chuck Hayes” from Monrovia is cold-hardy to zone 7, grows 4 feet tall and wide, and has semi-double ivory-white flowers.
To plant gardenias, dig the planting hole twice the width of the root ball. Planting gardenias too deep will cause them to die so do not dig any deeper than the depth of the soil in the container. Planting high will help prevent the roots from remaining too wet.
The visible root flare at the top of the root ball is planted just above the surface of the ground. If any soil is on top of that flare, take it off when planting.
Mulch the area to prevent weed growth. Regular watering is crucial the first season to have a healthy gardenia shrub.