Captivating Paeonia suffruticosa: Unveiling the “Bean Green” Beauty

The Paeonia suffruticosa, also known as the “Bean Green” or “Oubi”, is one of the four renowned varieties of peonies. This rare and precious flower blooms in an initial shade of green, fading to a lighter hue as it matures, and even appearing white under sunlight.

Its refreshing elegance and unique charm offer an unconventional beauty, making it a representative of the green peony species.

I. Basic Introduction

The Paeonia suffruticosa, or “Bean Green”, is one of the four famous peony varieties. This deciduous shrub can grow up to 2 meters tall and has short, robust branches. Its leaves are typically twice pinnate trifoliate, with the terminal leaflet being broadly ovate.

The leaf surface is green, hairless, while the back is pale green, occasionally powdered white, with sparse short soft hairs or nearly hairless along the veins. The flowers are singular and terminal, with unequal, elongated oval bracts.

The calyx leaves are green and broadly ovate. The flower is double, either crown-shaped or globular. The flower bud is round and often splits at the top; the flower is yellow-green, with irregular waves at the top.

The filaments are white at the top and the anthers are elliptical. The disc is leathery, cup-shaped, and purplish-red. The pistils are densely covered with soft hairs. The follicles are cylindrical and densely covered with yellow-brown stiff hairs. It blooms in May and fruits in June.

Bean Green peonies have a moderate growth rate, high flowering rate, and a propensity for tillering. As a rare and valuable variety, it is cultivated for viewing.

II. Morphology and Characteristics

The Bean Green peony is a deciduous shrub. The stem can grow up to 2 meters tall and has short, thick branches. The leaves are typically twice pinnate trifoliate, with the terminal leaflets being broadly ovate.

The medium-long leaves have a petiole length of approximately 12 centimeters. The leaflets are broadly ovate, 4.5-6.5 centimeters long, and 2.5-4 centimeters wide, with more notches, short pointed tips, and drooping. The leaf surface is green with a slight purple hue, and the back of the leaf is densely covered with velvet.

The flowers are either crown-shaped or globular. The flower bud is round and often splits at the top. The flower is yellow-green (144-D) with a diameter of 12×6 centimeters. The outer petals are 2-3 circles, thick and hard, with purple spots at the base.

The inner petals are dense and wrinkled. The stigma is petal-like or degenerate. The flower stem is thin and soft, causing the flower to droop. This variety is late flowering. The plant has a low stature and is spread out.

The branches are thin, the annual branches are short, and the internodes are short. The bud scales are narrow and pointed, shaped like an eagle’s beak, light brown-green, with the tips of the scales being red.

The plant has a moderate growth rate, high flowering rate, and a propensity for tillering.

III. Habit

This plant enjoys warm, cool, dry, and sunny environments. It prefers sunlight but can tolerate semi-shade. It can withstand cold, drought, and weak alkalis, but dislikes waterlogging, heat, and direct sunlight.

It thrives best in loose, deep, fertile, well-drained, neutral sandy loam soils. Growth is poor in acidic or heavy clay soils, with a pH of 6.5-7 being optimal.

Adequate sunlight is beneficial for its growth, but it cannot tolerate the intense sun in summer and enters a dormant state when temperatures exceed 25℃. The optimal flowering temperature is 17-20℃, but the flower must undergo a low-temperature treatment of 1-10℃ for 2-3 months before blooming.

It can withstand temperatures as low as -30℃, but in cold northern regions, appropriate frost protection measures must be taken in winter to avoid damage.

IV. Cultivation Methods

Planting: The soil should be loose, fertile, and slightly alkaline. Trim off the broken or diseased roots of the peony seedling and immerse it in insecticide and fungicide before planting it in a prepared pot or hole.

The root system should be spread out, and once the soil is filled halfway up the pot or hole, slightly lift and shake the seedling. Firmly pack the soil around it, with the depth at the root stem slightly below the surface of the pot or ground.

Watering: Water thoroughly after planting. Peonies dislike waterlogging, so water accordingly during the growing season.

In arid northern areas, water before and after blooming, and before the soil freezes. If the peony is potted, you may choose to bury the pot under the soil after the flowers have bloomed for easier management.

Fertilizing: One year after planting, fertilize in the fall, mainly using mature organic fertilizer. You can combine it with loosening the soil, spreading, or applying directly to the hole.

Use chemical fertilizer in the spring and summer, combined with watering before and after blooming. For potted peonies, you can combine watering with liquid fertilizer.

Pruning: The year of planting, prune evenly. After buds appear in the spring, leave about five branches and remove the rest to concentrate nutrients, ensuring larger, more vibrant flowers the following year.

In autumn and winter, prune dry flower stems, weak branches, and non-flowering branches while cleaning the garden. When potted, trim to your preferred shape as needed.

Cultivation: During the growing season, till the soil regularly, remove weeds, and watch out for diseases and pests. In the fall and winter, till the soil for peonies older than two years.

Repotting: If the potted peony has been growing for three to four years, repot in the fall into a larger pot filled with new, fertile soil or divide the plant.

Pest Control: Spray with lime sulfur before buds appear in early spring, and use a mixture of insecticide and fungicide in the summer. Depending on the condition of the plant, this should be done every two weeks.

When fertilizing, consider adding chemical fertilizer and growth regulator.

Forcing Blooms: To ensure blooming for holidays or celebrations, warm the peonies about 50 days in advance, maintaining a temperature of 10-25°C, averaging around 15°C daily. Keep the plants moist in the early stages, and once buds appear, ensure good ventilation and light.

Once the buds form, control the temperature based on the blooming period. Regularly fertilize the leaves and ensure sufficient water supply. This way, flowers can be seen in both winter and spring.

Viewing: The blooming period for a single peony plant is typically 10-15 days, shortening with rising temperatures. At 3-8°C, it can last over a month. For field planting, temporary shelters can be set up to protect from wind and light, extending the viewing period.

For potted peonies, move them to a place where the sunlight doesn’t directly hit them, with a temperature of 5-10°C, and good ventilation and light. Water as per the plant’s appearance and soil moisture level.

Avoid watering the flowers directly to extend the blooming period. When cutting flowers for arrangements, cut the stem underwater or scorch the cut to prevent disease. Add preservatives or a little sugar to the water to extend the life of the cut flowers.

V. Propagation Methods

Division

The specifics of division propagation are as follows: a thriving peony plant is dug up in its entirety and divided at the intersection where the root system meets.

The number of divisions depends on the size of the original plant, with larger plants yielding more divisions and smaller ones yielding fewer. Typically, each division consists of 3-4 branches and a relatively intact root system.

The roots are then lightly dusted with sulfur powder and clay, and the wounds on the roots are spread evenly. The divisions can then be planted separately. The best time to propagate by division is from the autumn equinox to the first frost each year.

During this period, the air and ground temperatures are higher, and the peony is in a semi-dormant state, but there is still a considerable amount of time for nutritional growth.

Division propagation does not severely affect root growth, and some new roots and a few plant buds can still emerge after planting. If division propagation is delayed, root growth will be weak that year, or no new roots will occur.

The following spring, plant development will be weaker, and the plant, having weak roots, will not be drought-resistant and may easily die. If division occurs too early, when air and ground temperatures are high, rapid growth can occur, which can trigger autumn sprouting.

The mother plant for peony division is typically a robust clump. Root tubers should be retained as much as possible on the mother plant used for division propagation.

All roots on the new shoots should be kept to multiply new shoots after 5 years of growth. Such plantlets are easy to survive and grow vigorously after planting. The more roots that are retained, the more vigorous the growth.

Grafting

Peony grafting propagation is divided into two types depending on the rootstock used: one uses wild peony, and the other uses peony root. The common methods of peony grafting are the inlay method, the belly grafting method, and the bud grafting method.

Inlay method: The peony root is used as rootstock, which is soft and heartless, easy to graft, thick and short, with sufficient nutrients, and grows vigorously after graft survival. If peony root is used for grafting, the wood is harder and grafting is more difficult, but its lifespan is longer.

The best time for grafting is from late September to early October each year. The rootstock used is a thick and pest-free peony root with a diameter of 2-3 cm and a length of 10-15 cm.

Belly grafting method: This is a method of high grafting to improve varieties. It uses the many branches of inferior peonies or 8-10 year old medicinal peonies to graft into different color excellent varieties. The grafting time is from early July to mid-August.

First, select a peony plant with excellent varieties, robust growth, and no pests or diseases. Cut the soil bud branches that grow from the ground or the short skills of the year that are 5-7 cm long, preferably short branches with 2-3 strong buds as scions. Leave a leaf petiole on the scion.

After selecting a good scion, cut a diagonal knife on the back of the bud at the lower part of the scion to form a horse ear shape, and then cut a wedge on the other side of the horse ear shape so that after grafting, both sides can be grafted to the wood.

The cambium between the part and the phloem is easy to survive. Before and after peony belly grafting, except for no irrigation during the rainy season, the appropriate humidity for the normal growth of the plant should be maintained.

Bud grafting is an effective method for peony propagation and cultivation of multiple varieties and colors on one plant.

Bud grafting method: This is done between May and July. Sunny days are preferable for grafting. There are two methods: the bark grafting method and the bud replacement method.

The bark grafting method involves cutting a rectangular or shield-shaped cut on the annual branch of the rootstock along with the wood, and then cutting a bud block of the same size and shape as the rootstock from the axillary bud of the scion along with the wood.

Then quickly attach the bud block to the cut on the rootstock and tie it tightly with plastic rope. The bud replacement method involves removing the axillary bud at the grafting site of the rootstock along with the cambium, leaving a complete bud embryo on the wood.

The axillary bud of the scion is then peeled off in the same way, quickly fitted onto the bud embryo of the rootstock, making sure the two are aligned, and finally tied tightly with plastic rope. The grafted plant should be watered, loosened, and fertilized in time to promote healing.

Cutting

Cutting propagation is a method of reproducing new plants by taking advantage of the easy rooting of peony branches, one of the asexual propagation methods.

The method is to cut the branch to be inserted first, separate it from the mother plant, and then insert it into the soil or other substrate to root and become a new plant.

The branches for peony cutting propagation should be the soil bud branches that grow from the peony root in the current year, or the branches that are solid, with full top buds and no pests or diseases selected during the peony shaping pruning. The length is 10-18 cm.

The root of the peony is a fleshy root, likes high dryness, hates dampness, and is drought-resistant. Therefore, the seedbed should be chosen in a ventilated and sunny place and built into a high bed for seedlings.

When inserting, water one bed after inserting one bed, and water it once thoroughly.