How to Grow Spiraea Thunbergii - Plant Care & Tips

By NorwichGardener Team   /   2024

Spiraea thunbergii is a plant species in the family Rosaceae. The plant is native to Japan, Korea and China. It is an evergreen shrub or small tree growing to 2–6 m tall. The leaves are alternate, simple, ovate to oblong-elliptic, 1.5–4 cm long and 0.5-3 cm broad, with a serrated margin. The flowers are white, borne in corymbs of 5-15 flowers in late spring or early summer. The fruit is a dry, brownish achene.

How to Grow Spiraea Thunbergii - Plant Care & Tips

Alternative name

  • False spiraea
  • Thunberg spiraea
  • Dropwort
  • Meadowsweet
  • Prunus padus

Basic info

  • Spiraea thunbergii is a deciduous shrub native to Japan.
  • It grows to 3–5 m (10–16 ft) tall and wide.
  • The leaves are obovate, 2–4 cm (0.8–6 in) long and 1–2 cm (0.4–0.8 in) wide, with a serrated margin.
  • The flowers are white, borne in corymbs of 5–15 blooms.
  • The fruit is a small, dark brown achene.
  • Spiraea thunbergii is named after the Swedish botanist Carl Peter Thunberg.
  • It is commonly known as the bridal wreath spiraea or the Japanese snowball.
  • It is often used as an ornamental plant in gardens.
  • It is tolerant of a wide range of soils and conditions.
  • It can be propagated by seed, cuttings or division.

Related plant:
Spiraea Grefsheim

How to Grow

  1. For spiraea thunbergii, first step is to choose the right spot. They prefer full sun, but partial sun is also fine.
  2. The next step is to prepare the soil. They prefer well-drained soil.
  3. The third step is to plant the spiraea thunbergii.
  4. The fourth step is to water them regularly.
  5. The fifth step is to fertilize them.
  6. The sixth step is to prune them.
  7. The seventh step is to deadhead them.
  8. The eighth step is to check for pests and diseases.
  9. The ninth step is to mulch them.
  10. The last step is to enjoy your beautiful spiraea thunbergii!

Related plant:
Spiraea Betulifolia

The Soil

About soil condition, the Spiraea thunbergii aka Japanese Spiraea, is a deciduous shrub that is native to Japan. It prefers full sun to partial sun and well-drained soil, but it is adaptable to different conditions. This plant is low-maintenance and easy to care for. It is also tolerant of salt and pollution, making it a good choice for urban gardens.

About light

Just like other types of Spirea, the Thunberg Spirea (Spiraea thunbergii) shrub is known for its beautiful clusters of flowers that bloom in the spring. But this particular variety is unique in that it is one of the few that can tolerate full sun. Most other varieties prefer partial sun or shade, but the Thunberg Spirea will do just fine in an area that gets six or more hours of sunlight per day. This makes it a great choice for planting in sunny borders or near patios and decks where other plants might scorch in the summer heat.

Ideal Temperature

The temperature condition that is ideal for Spiraea thunbergii is between 60 and 65 degrees Fahrenheit. This plant is native to Japan, and it was first introduced to the United States in the late 1800s. The plant is named after the Japanese botanist, Carl Peter Thunberg.

Humidity Level

Ideal humidity condition for this plant is moderate to high. It can tolerate some drought, but not excessive dryness. If the air is too dry, the leaves will begin to drop. If the air is too moist, the leaves will develop brown spots.

Fertilizer Requirement

Discussing fertilizer, usually the plant food is classified into three main types: - Primary nutrients: these are the big three of plant food, nitrogen (N), phosphorus (P), and potassium (K). All three of these elements are essential to proper plant growth. - Secondary nutrients: these nutrients are not required in as large of quantities as the primary nutrients, but are still essential to plant health. These include calcium (Ca), magnesium (Mg), and sulfur (S). - Micronutrients: these nutrients are needed in very small quantities, but are still essential to plant health. These include iron (Fe), manganese (Mn), boron (B), copper (Cu), molybdenum (Mo), and zinc (Zn).

Plant Pruning

Pruning your spiraea thunbergii (spiraea thunbergii) is a great way to keep it healthy and looking its best. Pruning will encourage new growth, help to keep the plant compact and bushy, and prevent it from getting too leggy. When pruning, be sure to remove any dead or dying branches, as well as any branches that are crossing or rubbing against each other. You can prune your spiraea thunbergii in late winter or early spring.

The Propagation

Propagation of the Spiraea thunbergii, or Japanese spirea, is best done through softwood cuttings taken from new growth in the spring or early summer. The cuttings should be about 6 inches long and taken from the tips of the branches. They should be placed in a moistened soil mix and kept under high humidity until they have rooted. Once they have rooted, they can be transplanted into individual pots or into the garden.

Growth Speed

Usually, the plant growth rate during the spring and summer. However, some species may have a growth spurt during the fall season. The average height is 3 to 6 feet, but some specimens can reach up to 12 feet tall. The growth rate is about 1 to 2 feet per year.

Basic Problems

Common problems for this kind of plant are witches'-broom and Japanese aphids. These pests can cause the plant to become misshapen, with leaves and branches growing in abnormally. If left untreated, these problems can kill the plant.

Tips on Growing

  • If you're growing spiraea thunbergii from seed, start them indoors in late winter or early spring.
  • Provide plenty of light for your seedlings, as they need it to grow well.
  • Once they've germinated, transplant them into individual pots.
  • Growing spiraea thunbergii in containers is possible, but make sure the pot is large enough to accommodate the plant's roots.
  • Water regularly, as this plant prefers moist conditions.
  • Fertilize every few weeks with a balanced fertilizer.
  • Deadhead faded flowers to encourage more blooms.
  • Prune back hard in late winter or early spring to encourage new growth.
  • This plant is generally disease and pest-free, but watch out for aphids and powdery mildew.
  • If you live in a cold climate, you may need to protect your plants from

Related Plants

  • Spiraea Salicifolia is a species of flowering plant in the rose family Rosaceae, native to the eastern Pyrenees. The common name is willowleaf spiraea.
  • Spiraea japonica, known as Japanese spiraea or Japanese meadowsweet, is a species of flowering plant in the rose family Rosaceae, native to eastern Asia in China, Korea and Japan.
  • Spiraea betulifolia is a species of flowering plant in the rose family Rosaceae, native to central and eastern Asia in China, Mongolia, Japan, and the Russian Far East.
  • Spiraea tomentosa, commonly known as hardhack, steeplebush, steeple-leaved spiraea, or swelling bush, is a species of flowering plant in the rose family Rosaceae, native to eastern North America.
  • Spiraea x arendsii is a species of flowering plant in the rose family Rosaceae, native

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