Hardy Gardenia
The heady scent of Gardenia flowers wafting through thick summer air is nothing short of scrumptious!
Plant care & info
Family: Rubiaceae
Genus: Gardenia
Common: Gardenia or Cape Jasmine
China
White waxy flowers have a strong and distinctive fragrance. The leaves are dark green and glossy. Grows well in acidic soil, which (lucky us) is what we have here in Portland.
It’s best to plant hardy Gardenia in the spring so that it can set strong roots before winter. Gardenia loves sun, but they should be planted in a spot that gets afternoon shade. Gardenia is not drought tolerant, and needs deep, weekly watering during dry seasons and more frequent watering during heat waves. Gardenia dislikes root disturbance, so don’t plant labor intensive plants around the base. Remember, nighttime temperatures between 50-55°F are necessary to form flower buds, so be patient—it’ll happen eventually!
Size varies per variety and ranges between 12” tall and 5’ tall.
Until very recently Gardenias were tropical shrubs, hardy in climates with winters warmer and drier than ours. Many varieties are still in that group, but several new forms have been released in the past few years that are more cold tolerant.
Gardenias are big eaters! They need to be fertilized during the growing season to produce abundant flowers. Use water soluble fertilizers and soil amendments for acid-loving plants (Rhododendron food) and make sure not to add lime to raise soil pH.
To grow gardenias well in containers, use a quality potting soil and a container with drainage holes, and pick the container size based on the current and future size of the plant. Do not put a little shrub in a big pot, as it will stay too wet. Change the size of the pot periodically to coincide well with the size of the shrub. Watering should always be done moderately. This means that you never let a gardenia sit fully dry or wilt, nor do you water unless the soil is getting to be partly dry, and dry at the surface. Poor watering is the most common way to end up with a poorly grown or dead plant.
Gardenias are susceptible to several pests and diseases. Whitefly, aphids and scale are common insects that can affect Gardenias. When any of them are present they may be accompanied by black sooty mildew along stems and leaves. These are far more likely to be a problem for plants that spend all or part of their lives indoors. Bud drop–when flower buds form, look like they are going to open, but turn yellow and drop off instead–can be an issue as well. Common causes include overwatering, underwatering, insufficient light, high temperatures and low humidity. Again, this is far more common when Gardenias are grown as houseplants.
Gardenias should be grown in part to full sun during the growing season for best results. For this reason, they do not grow their best nor bloom reliably in a typical living room environment. They grow best outside for the majority of the growing season, or in a greenhouse or sun room year-round. Most gardenias flower in spring to summer, though some can re-bloom during other seasons. Pruning should therefore be done after flowering, but only if it is necessary to maintain a manageable size or a pleasing shape to the plant. Do not prune without a reason.
For what seemed like eons, Portland gardeners were relegated to growing Gardenias that would die if left outdoors in winter, but in the last 10 years, several hardy types have emerged, and they’re pretty darn good plants. Aren’t we lucky to live in the era of Hardy Gardenias?
