Hardy Gardenia

The heady scent of Gardenia flowers wafting through thick summer air is nothing short of scrumptious!

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?

To be successful follow a few tips:

Plant in spring so Gardenias have a chance to set strong roots before winter.
Gardenias are big eaters! They need to be fertilized to produce abundant flowers. Use fertilizers and soil amendments for acid-loving plants (Rhododendron food) and make sure not to add lime - this raises soil pH.
Night temperatures between 50-55f are necessary to form flower buds, so be patient - it'll happen eventually.
Gardenias dislike root disturbance, so don't plant labor intensive plants around the base. Do add mulch to the root zone, making sure not to pile it around the base of the shrub.
You may be surprised, but Gardenias like a bit of a break from the heat of the day! Plant them in a spot with afternoon shade.
Gardenias are not drought tolerant. They need deep, weekly watering during dry seasons and more frequent watering during heat waves.

There are new varieties coming out every year, but we consistently carry the following varieties:

Gardenia jasminoides ‘Kleim’s Hardy’

White flowers are single form with six petals and yellow stamens. Fragrance is classic Gardenia. Leaves are dark green, glossy and evergreen. Grows slowly in a rounded mounding habit to 2-3 feet tall and wide. Z7

Gardenia jasminoides ‘Chuck Hayes’

White flowers are double form with many fat petals and sweet scent. Evergreen leaves are dark green & glossy.

Grows 4' x 4', Z7

Gardenia jasminoides ‘Frost Proof’

Our favorite hardy Gardenia so far, 'Frost Proof' is an over achiever. Large white double flowers with narrow petals and sweet Gardenia scent. Evergreen leaves are dark green & glossy but more narrow than other varieties. Growth is upright and vase-shaped, to 3-4’ tall. Z7

Availability

March-September

Facts: Hardy Gardenia

Family: Rubiaceae

Genus: Gardenia

Common: Gardenia or Cape Jasmine

Origin: China

Characteristics: White waxy flowers have a strong and distinctive fragrance. Leaves are dark green and glossy. Grows well in acidic soil, which (lucky us) is what we have here in Portland.

Size: Size varies per variety and ranges between 12” tall and 5’ tall.

Hardiness: 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.

Problems: 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 - Flower buds form, look like they are going to open, but turn yellow and drop off instead. 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 in pots

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 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. Feeding can be done with an acidic, water soluble fertilizer during the growing season.

Find the Perfect Shrubs for your garden

Read up on some of our favorite shrubs and remember, this is only a smattering of the variety of shrubs we carry all year long! Note: Viewing a Native Plant will take you into our Native Plant section.