Stewartia

( stew - AR - tee - uh )

At-A-Glance Information

This genus of deciduous small trees and shrubs, alternatively spelled Stuartia, includes species which need full sun to partial shade and regular water to perform well in the landscape. These plants are native to two distinct regions: eastern Asia and the southeastern United States, and are slow-growing. Leaves are green and emerge in early springtime and flowers are white, blooming in summer after many other plants have finished flowering. In fall, foliage turns orange and red. In wintertime, branches and trunks of these trees form beautiful silhouettes and have smooth bark that flakes off, giving it a multicolored look. These trees and shrubs are wonderful for woodland gardens and as a foreground specimen. They are also beautiful in entryways and around patios, to anchor building corners, or in compact urban spaces.

stewartia Species and Varietals

The genus Stewartia includes between 8 and 20 species and is a member of the plant family Theaceae. The plants in this genus are closely related to those in Camellia and Franklinia (Franklin Tree). It was formally named in 1753 by Carl Linnaeus to honor John Stuart, 3rd Earl of Bute. Unfortunately, he was given the wrong spelling of Stuart's name for his publication, and the genus became widely known as Stewartia instead of Stuartia. Stewartia grows best in USDA hardiness zones 5-8 or Sunset growing zones 4-6, 14-17, 20 and 21, though this varies somewhat depending on the species cultivated. For more information, see the descriptions below. To find your zone, click here: Zone Map.

Stewartia malacodendron (Silky Camellia, Silky Stewartia, Virginia Stewartia, Round-Fruited Stewartia)
These plants are slow growers, eventually forming large deciduous shrubs or small trees, typically reaching between 10 and 15 feet tall (at maximum 30 feet tall). Flowers are white and cup-shaped, blooming from April through August. Woody seed capsules follow flowers. This species is suited for USDA hardiness zones 6-9.

Stewartia monadelpha (Tall Stewartia, Orangebark Stewartia, Little Shara, H ime-Shara, ヒメシャラ, 姫沙羅, Large Japanese Noggak Tree, Geun-il-bon-nog-ak-na-mu, 큰일본노각나무 )
These plants reach up to 25 feet tall and 20 feet wide at maturity with branches angled towards the sky. Fall foliage is red, and flowers are small and white. Bark is rich brown when new and matures to a striking light tannish-brown. These plants can form deciduous shrubs or multi-stemmed trees and prefer temperate rainforest climates. They are native to Japan and South Korea.

Stewartia ovata (Mountain Camellia, Mountain Stewartia, Summer Dogwood)
These slow-growing small trees are native to low-elevation areas around the southern end of the Appalachian Mountains. They have a limited range, and are considered uncommon. The species reaches up to 16 feet tall, produces green foliage, flaking grey-orange bark, and white flowers in early to mid-summer.

Stewartia pseudocamellia (Japanese Stewartia, Korean Stewartia, Deciduous Camellia, Summer Camellia, Natsu Tsubaki, 夏椿, Overripe Cucumber Tree, Nogakamu, 노각나무)
This pyramid-shaped tree reaches 30-40 feet tall and 20-25 feet wide at maturity with leaves that turn orange-red in fall. Flowers are cup-shaped and have orange anthers, and colorful bark. This species is native to Japan and Korea.

Stewartia rostrata (Beaked Stewartia, Upright Stewartia, Cháng Huǐ Zǐ Jīng, 长喙紫茎)
These plants are fantastic trees for smaller gardens, and are native to southeastern China. They are deciduous, reaching between 13 and 33 feet tall when mature. White (sometimes with a pink flush) flowers bloom from May through July, followed by woody beaked capsules in September. Bark is greyish brown, and twigs are reddish brown. Leaves are dark green in spring and summer, transitioning to beautiful hues of dark pink, red, and maroon in fall.

Caring for Stewartia

Plant Stewartia in a location that receives partial shade to full sun; in warmer regions they will need some afternoon shade. Ideally, they like to get 4 to 6 hours of morning sun. Well-draining soil is essential. Stewartia plants prefer acidic soil, with a pH of between 4.5 and 6.5 (no chalk or calcium-rich soil for these guys), and for soil to be kept consistently moist, especially during periods of drought. If local soils are particularly poor in nutrients or do not drain well, make sure to amend the planting area with plenty of organic compost before installing. Apply a layer of mulch around the base of the plant after installation to help retain soil moisture and discourage weed growth. Water new trees and shrubs regularly as they establish themselves in the landscape.

Fertilize yearly in early springtime with an application of 2 inches of compost around the base of plants. Pull mulch back before applying, work the compost gently into the soil a bit, water it in, and then replace mulch. In areas with strong winds, these plants may need some protection to prevent wind burn and drying out of leaves. Young plants should be pruned to establish a desirable shape and central leader (if pruning into a single-trunked tree). Once established, however, pruning requirements for these plants are minimal. The best time to prune Stewartia is in the early spring, before new growth starts. At this time, remove dead, damaged, or diseased branches and lightly shape if necessary. These trees and shrubs naturally have a very handsome shape and do not need much pruning. These trees have a moderate to long life span, able to survive for 70 to 150 years or more under ideal growing conditions. They are slow-growing, often taking up to 15 to 30 years to reach their full ornamental potential and mature size.

Propagation

Stewartia can be propagated either by using cuttings or from seed. To ensure that your propagated plant will have the exact same qualities and characteristics as the parent plant, use the cutting method. If you would like to experiment and see what plant you can grow from seed, just keep in mind that it will not necessarily be the same as the parent plant. To propagate your plant, follow the instructions below:

Propagating Stewartia by Cutting

Gather your materials. You'll need a clean, sanitized, sharp pair of garden shears, rooting hormone, a pencil, and a 3-inch pot filled with well-draining compost or other organic material. A good substrate for propagation of cuttings is a light blend of 1/3 pasteurized soil or compost, 1/3 sand, vermiculite or perlite, and 1/3 coconut coir or peat moss.
In spring or early summertime, choose the plant that you'd like to propagate. Ensure that this plant has had a good watering the night before, as this will improve the chances your cutting will take root. Cut one or more 6 inch portion(s) of the end of a non-blooming branch and strip the leaves off of the lower half. Make a hole in your planting medium by pushing your pencil into the soil. Dip the end of the stem in rooting hormone, and plant it in your pot. Fill in soil around the cutting to support it, but do not pack it down too much.
Moisten with water, and ensure that the pot has good drainage. Your pot should be kept in warm, sunny conditions indoors (and not in direct sunlight). Water whenever your soil is dry under the top layer. After about four to six weeks have passed, your cutting should be rooted. When you notice new growth, you'll know you have roots.
Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring, when you can transplant it to its new home. Ensure that the last frost of the year has occurred before doing this, as it can seriously damage your new shrub.

Propagating Stewartia by Seed

Keep in mind that the plant you get from seed will not necessarily mimic all of the characteristics of the parent plant. To propagate by seed, you will need a paper bag, a plastic sealable bag, peat moss, a pot or tray filled with well-draining compost or other organic material, a spray bottle and a fork. The best potting medium for seed germination is a light blend of 1/3 pasteurized soil or compost, 1/3 sand, vermiculite or perlite, and 1/3 coconut coir or peat moss.
Harvest your seeds. The seed pods are pretty easy to spot, they're beaked and are left behind after flowers have faded. Once they have dried out and begun to split open, harvest the seeds inside. Cut them off of the plant, placing them in a paper bag. Harvest as many as you can, and place the paper bag in a dry, cool, dark area. They will begin to split open and release the seeds contained inside. Once they have been released, take them out of the bag and put them in a container so you can work with them. They are best treated and sown fresh, but can be stored for about a year (dried and then placed in a sealed container in a cool, dark, dry area) before their germination rates drop off significantly.
Stewartia seeds need to be treated in a few ways before being sown to break seed dormancy. Once harvested, place your seeds in a baggie filled with moistened peat moss, and place the bag in an area where it will stay around 60-65 degrees Fahrenheit. Leave the bag there for 120 days, adding moisture to the bag as needed. After this period has ended, move the bag to your refrigerator for 90 days. Once these two treatments have been completed, remove the seeds from their peat moss medium.
Water your prepared seed tray or pot filled with soil, and ensure that good drainage is occurring. Place your seeds in your prepared pot or seed tray about a quarter inch to a half-inch under the soil surface. Cover them with soil and water with your spray bottle. Place your tray of seeds in a warm area (around 68 degrees Fahrenheit) that receives bright, indirect light. A greenhouse is the most ideal climate, but a planting tray inside a window will do as well. Germination can take between 1 and 3 months and is erratic. Once you begin to see seedlings sprout and they are able to be handled, transplant them to their own individual 3-inch pots, filled with the same potting medium as described in Step 1. Loosen the seedlings from the potting medium by digging down with the tines of your fork about an inch and a half, gently working the seedling up until it is out. Then, replant the seedling in its individual pot.
Keep the seedling's potting medium moist, but not wet, by spraying the soil with your spray bottle. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring (after the danger of frost has passed), when you can transplant it to its new home.

Stewartia plants produce dry, beaked oval capsules that each contain up to 20 seeds.

Stewartia seeds are about 1/4-in. long and flattened.

Problems and Pests

Stewartia is generally a disease and pest-resistant genus, however it is still a good practice to keep an eye out for the following common garden pests and issues: