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Growing Alcea Rosea: Tips for Thriving Tower of Jewels

The Alcea rosea, also known as “Tower of Jewels,” “Majestic Giant,” and “Roman Hollyhock,” is a biennial herb that can grow up to 2 meters tall. Its stems and branches are densely covered with bristly hairs. The leaves are nearly orbicular-cordate, measuring 6-16 centimeters in diameter, with 5-7 shallow lobes or wavy edges. The lobes […]

The Alcea rosea, also known as “Tower of Jewels,” “Majestic Giant,” and “Roman Hollyhock,” is a biennial herb that can grow up to 2 meters tall. Its stems and branches are densely covered with bristly hairs.

The leaves are nearly orbicular-cordate, measuring 6-16 centimeters in diameter, with 5-7 shallow lobes or wavy edges. The lobes are triangular or circular, with the central lobe about 3 centimeters long and 4-6 centimeters wide.

The upper surface is sparsely covered with stellate pubescence and feels rough, while the underside is coated with long stellate hard hairs or down.

Alcea rosea

The flowers present in terminal racemes, either single or double-petaled, in shades of purple, pink, red, and white. The flowering season spans from June to August, producing schizocarps with flattened, reniform seeds.

The plant thrives in full sunlight to partial shade and prefers well-drained conditions, but does not tolerate waterlogging. It is native to the southwestern regions of China and is widely distributed across the country, as well as globally cultivated.

There are many horticultural varieties, including ‘Chater’s Double’, ‘Black Knight’, and ‘Nigra’, with foreign cultivars also being numerous.

Alcea rosea

Hollyhocks are ideal for planting beside buildings, rockeries, or as embellishments in flower beds and lawns, either in rows or clusters. The root can be used as a demulcent in the treatment of mucous membrane inflammations, providing a protective and soothing effect.

I. Morphological Characteristics

The Hollyhock is a biennial erect herb that can reach up to 2 meters in height, with stems and branches thickly covered in bristly hairs. The leaves are nearly heart-shaped, 6-16 centimeters in diameter, with 5-7 shallow lobes or wavy edges.

The lobes are triangular or round, with the central one being about 3 centimeters long and 4-6 centimeters wide. The upper surface is sparsely covered with stellate pubescence, and the underside with long stellate hard hairs or down.

Leaf petioles are 5-15 centimeters long, covered with long stellate hard hairs, and the stipules are ovate, about 8 millimeters long, with a three-pointed tip.

The flowers grow from the axils, either singly or in near clusters, arranged in raceme-like inflorescences with leaf-like bracts.

The pedicels are about 5 millimeters long, extending to 1-2.5 centimeters when fruiting, and are coated with long stellate hard hairs.

The small bracts are cup-shaped, usually with 6-7 lobes, ovate-lanceolate, 10 millimeters long, densely covered with coarse stellate hairs, and fused at the base.

The calyx is bell-shaped, 2-3 centimeters in diameter, with 5 toothed lobes, the lobes ovate-triangular, 1.2-1.5 centimeters long, densely covered with coarse stellate hairs.

The flowers are large, 6-10 centimeters in diameter, available in red, purple, white, pink, yellow, and dark purple, with single or double petals that are obovate-triangular, about 4 centimeters long, notched at the tip, with a narrow base and claw covered with long beards.

The stamen column is hairless, about 2 centimeters long, with slender filaments about 2 millimeters long and yellow anthers. The pistil has many branches, slightly hairy. The flowering period is from February to August.

The fruit is disc-shaped, about 2 centimeters in diameter, covered with short soft hairs, with the mericarps nearly circular, numerous, with a thick back up to 1 millimeter, and featuring longitudinal grooves.

II. Growing Environment

Hollyhocks prefer abundant sunlight and tolerate partial shade but do not withstand waterlogged conditions. They have a strong saline-alkali tolerance and can grow in soils with up to 0.6% salt content.

They are cold-hardy, capable of overwintering outdoors in northern China. They flourish in loose, fertile, well-drained, organic matter-rich sandy soil.

III. Distribution Range

Originally from China, hollyhocks are now widely cultivated around the world.

IV. Growth and Propagation

Hollyhocks are typically propagated by seed but can also be propagated through division and cuttings.

Division should be done in spring, while cuttings are reserved for propagating select high-quality varieties. Seed propagation is predominantly used in commercial production.

Seeding

Seeds germinate about a week after sowing. Seedlings are transplanted once they have developed 2 to 3 true leaves.

Hollyhock seedlings are prone to damping-off disease, so it’s crucial to manage the soil in the seedbed well, using a mix of leaf mold and field soil and applying soil fumigation or seed dressing at the time of sowing.

Division

Propagation by division can be done from August to September. Dig up the old plants, divide the stems with fibrous roots, and replant. Water thoroughly immediately after planting, and flowers should bloom the following year.

Cuttings

For cuttings in the spring, select stem shoots that have sprouted at the base. Cuttings should be 7 to 8 centimeters long, planted in sandy soil, and shaded until roots develop.

V. Pest and Disease Control

Hollyhock Rust

Perennial hollyhocks are susceptible to rust, which causes leaves to yellow or die and manifests as brownish-red, powdery spore masses on the undersides of leaves.

Control Methods

  • Spraying Bordeaux mixture on plants in spring or summer or disinfecting seeds before sowing can prevent the disease.
  • At the initial stage of infection, apply a 1000-fold dilution of 15% Dustine WP, a 1000 to 1500-fold dilution of 70% Methylobenzene WP, or a 600-fold dilution of 75% Chlorothalonil WP every 7 to 10 days for 2 to 3 consecutive applications for effective control.

Red Spider Mites

Red spider mites can be a problem during the growing period.

Control Methods

In severe cases, spray with a 7000 to 9000-fold dilution of 1.8% Abamectin EC or a 2500 to 3000-fold dilution of 15% Dicofol EC for effective control.

Avoid using Dichlorvos to kill mites, as it can stimulate their proliferation. Do not use pyrethroids as they are generally ineffective in controlling mites.

VI. Main Value

Ornamental

If you wish to give flowers to your beloved or girlfriend to praise her gentle nature and her qualities as a wife and mother, consider the red hollyhock, which symbolizes gentleness.

The red hollyhock is beautiful, with its vibrant color offering a refreshing appeal that is highly admired. It is particularly suitable for planting in courtyards, alongside roads, and for arranging floral landscapes.

It can also be used to create lush green hedges and flower walls, enhancing garden aesthetics and imparting a gentle ambiance to its surroundings.

There are many horticultural varieties, including ‘Thousand Petals’, ‘Five Hearts’, ‘Double Deck’, ‘Velvet Cut’, and ‘Serrated’, with many superior varieties also developed internationally.

They are well-suited for planting beside buildings, rockeries, or as accents in flower beds and lawns, either in rows or clumps.

Dwarf varieties can be potted and displayed at entrances but should not be kept indoors for extended periods. They can also be cut for vases, baskets, or bouquets.

Medicinal

Therapeutic Uses

Root: Cools heat, detoxifies, promotes pus drainage, and has diuretic effects. Used for enteritis, dysentery, urinary tract infections, painful urination, cervicitis, and leukorrhea.

Seeds: Promote urination and relieve gravel. Used for urinary stones, difficult urination, and edema.

Flowers: Facilitate urination, detoxify, and reduce swellings. Used for urinary difficulties, plum pit qi, and can also neutralize pufferfish poison.

Flowers and Leaves: Used externally to treat boils, ulcers, and burns.

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Peggie

Peggie

Founder of FlowersLib

Peggie was once a high school mathematics teacher, but she set aside her chalkboard and textbooks to follow her lifelong passion for flowers. After years of dedication and learning, she not only established a thriving flower shop but also founded this blog, “Flowers Library”. If you have any questions or wish to learn more about flowers, feel free to contact Peggie.

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