Japanese camellia

Identification and origin

Camellia japonica belongs to the Theaceae, the tea family. In the wild it grows in China, Korea, Japan, the Ryukyu Islands and Taiwan. The genus name honors Georg Josef Kamel (1661–1706), a Jesuit missionary and naturalist who studied the flora of the Philippines; the epithet japonica means “Japanese.”

It is an evergreen shrub, sometimes a small tree, dense and formal in outline, slow-growing but very long-lived: some specimens around the imperial palace in Japan are said to be more than five centuries old. With age it can reach 25 ft, but it is usually 6–12 ft tall and 6–10 ft wide. The alternate, oval, finely toothed leaves are leathery and glossy dark green, 2–4 in long.

The flowers, 3–5 in across, range from white through every shade of pink and red, often variegated. They can be single, semi-double, peony-form or formal double, with perfectly overlapping petals. Depending on the cultivar, bloom runs from fall into spring, and each plant stays in flower for three to four weeks.

Among thousands of cultivars, classics include ‘Adolphe Audusson’ (semi-double, dark red), ‘Nuccio’s Gem’ (white, formal double), ‘Pink Perfection’ (pink, early) and ‘Lady Clare’ (deep pink, slightly more cold-hardy than average).

Light

A woodland plant, camellia prefers part shade or light, dappled shade. Too much sun, too much shade or too much cold all reduce flowering, and afternoon sun scorches the leaves; an older plant whose canopy shades its roots tolerates more sun.

Shelter it from cold, drying winter winds and from early morning sun: flowers that freeze and then warm up quickly in the morning turn brown much sooner.

Watering

Summer is the critical season, because that is when the plant sets next year’s flower buds. Drought in late summer or early spring makes the buds abort. Keep the soil evenly moist, never soggy.

Rather than watering on a fixed schedule, check the soil about 4 in down: if it is dry at that depth, water deeply. Check containers more often. A newly planted camellia needs close attention for about a year and a half.

Use rainwater rather than hard, alkaline tap water whenever you can. A 2–3 in layer of mulch reduces evaporation and protects the shallow roots. Too much water is just as harmful: it suffocates the roots and encourages edema on the leaves.

Potting mix

Camellia needs acidic soil, ideally pH 5.5–6.5, rich in organic matter and well drained. It will not tolerate alkaline soil: if rhododendrons thrive in your garden, the soil will suit it. On alkaline ground, grow it in a container of peat-free ericaceous (acid) mix.

Its roots stay near the surface: plant it in a wide hole no deeper than the root ball. In containers, feed in early spring with a fertilizer for acid-loving plants, following the label rate. Do not feed after midsummer: late or excessive feeding causes bud drop, scorched leaf edges and leaf drop.

Temperature

In the ground, Camellia japonica is hardy in USDA zones 7a to 9b and generally withstands lows of about 5–14 °F. Flower buds are more tender: cold around -0 °F can kill them. Young shoots dislike late frosts; frost cloth gives about 36 °F of protection.

In containers the roots are far more exposed: in hard freezes, move the pot against the house, wrap it in bubble wrap, or shelter it in an unheated greenhouse or sunroom. Do not let the root ball drop below 14 °F. At the other extreme, a heat wave can leave large brown blotches on the leaves.

Repotting

In the garden, fall is the best planting season, while the soil is still warm. In containers, the mix eventually compacts and holds too much water: repot then into fresh ericaceous mix, without burying the base of the stem any deeper.

Choose a container only slightly larger than the old one: an oversized pot holds a mass of wet mix that the roots do not reach, which encourages root rot.

Pruning

Camellia needs almost no pruning: remove dead wood, unproductive branches and overly long shoots. Next year’s buds form on existing wood, so prune right after flowering or in early summer, never later, or you will sacrifice the following bloom.

An overgrown plant tolerates hard pruning in late winter, but it will take two years or more to flower well again. Disinfect blades between cuts (one part household bleach to nine parts water).

Propagation

Semi-ripe cuttings are the most common method: in mid- to late summer, take shoots of the current season that are firm at the base but still soft at the tip. They root better if you remove a thin strip of bark about 1 in long at the base. Hardwood cuttings are taken from fall to late winter and can root in about three months.

Layering and grafting are also used. Seed is possible, but because the flowers are cross-pollinated, seedlings usually do not reproduce the parent’s flower.

Common problems

• Bud drop: dry soil in late summer or early spring, late or excessive feeding, winter cold; some bud drop is also natural, since the plant sets more buds than it can open.
• Flowers browning fast: frost followed by morning sun, gray mold or camellia petal blight (Ciborinia camelliae); remove all affected flowers.
• Yellow leaves with green veins: chlorosis from soil that is too alkaline; apply iron chelate and water with rainwater. A few old leaves yellowing inside the plant in spring or summer is normal.
• Black coating on leaves: sooty mold growing on the honeydew of scale insects, small brown scales under the leaves with white, waxy egg masses; treat with horticultural oil in late winter.
• Swollen, whitish leaves: camellia leaf gall, not serious; pick them off before they turn white with spores.
• Corky spots under the leaves: edema from excess water.
• Dying branches: root rot (Phytophthora), waterlogging, canker, or black vine weevil larvae in containers.
• Other pests: aphids, spider mites.

A single symptom can have several causes: check the root ball, exposure, pH and roots before treating.

Toxicity

Camellia is listed as non-toxic to dogs, cats and horses, and no toxicity has been reported in people, which makes it a good choice for a garden shared with pets. If an animal shows unusual symptoms, consult a veterinarian anyway.