Can Peonies Be Grown in Pots? A Detailed Guide to Potting and Caring for Tree Peonies

Tree peonies are mainly grown in the ground, but to make better use of their ornamental value, they can also be grown in pots. However, this requires attention to cultivation methods and proper management; only then can the plants have upright, graceful branches and leaves and produce brilliant blooms. Generally, grafted seedlings on herbaceous peony roots are chosen for potting, as they adapt better. At the same time, the pot should be deep (at least 30 cm deep), because tree peonies are deep-rooted plants. The transplanting time is from early October to late December. When transplanting, dig up the ground-grown tree peony, trying not to damage its roots.

If transporting over a long distance, the soil can be gently patted off, and the fleshy roots tied tightly and evenly with rice straw to avoid damaging the root system during shipping. The potting soil should be loose, well-drained, fertile soil; generally, use 60% garden soil and 30% leaf mold or mountain soil, mixed with 10% rice husk ash.

Preparation Work Before Potting

Before potting tree peonies, the main tasks are preparing the growing medium and getting the flower pots ready. Tree peonies are valuable deep-rooted fleshy ornamental plants with few fibrous roots, so when grown in pots, the limited pot volume relatively reduces the root's nutrient area, which can easily cause an imbalance between the underground and aboveground parts, thus affecting the normal growth and development of potted tree peonies. Therefore, to keep potted plants alive and produce fresh, brilliant flowers, not only are the cultivation and management techniques relatively strict, but the growing medium must also be scientifically prepared. The growing medium should be prepared one month before potting, and can only be used after it has decomposed.

According to the growth characteristics of tree peonies, the growing medium should be loose, fertile, high in humus content, long-lasting in fertility, and easy to drain. A relatively ideal growing medium formula is to mix humus soil, horse manure (sheep manure or cake fertilizer), garden soil, and coarse sand or furnace slag in a 2:1:2:1 ratio and blend evenly. Then seal it with human urine and let it decompose for a period before use. When first planting, smaller flower pots can be used; a clay pot with a 30 cm diameter and 25 cm depth will do. When blooming, it can be switched to a larger clay pot with a 35 cm diameter and 30 cm depth.

Potting Time and Method

The suitable time for potting tree peonies is the same as for field division; in Heze and Luoyang, it is generally best from late September to early October. Planting too early easily causes "autumn growth"; planting too late results in slow root growth and weak plant growth, and the plant may even die after flowering the following year. Before potting tree peonies, first dig out the seedlings and let them dry in the sun for 1-2 days, so the roots lose water and soften, making pruning and planting easier. Before planting, place the flower pot in a water tank to absorb enough water. When planting, first place a piece of tile over the drainage hole at the bottom of the pot to prevent soil loss; then spread a 2-5 cm thick layer of small stones or discarded palm rope and similar materials to improve drainage. Before planting, the tree peony seedlings must also be shaped and pruned to balance the aboveground and underground parts, create a beautiful and elegant form, and make cultivation and management easier. First cut off dead branches and fallen leaves and overly long roots, and disinfect the roots with a 1% copper sulfate solution for 5-10 minutes. Then place the seedling in the center of the pot and fill with soil, pressing down with your hands as you fill, until the soil is 3-5 cm below the rim of the pot, then stop filling.

After potting, the surface of the pot can be decorated with Taihu stones, Ying stones, or bamboo shoot stones placed alongside the tree peony. This not only enhances the beauty of the potted tree peony, making the pot surface lush and full of life, but also helps retain moisture and insulate temperature.

Watering

Because pots have a smaller capacity and hold less soil, their water-holding capacity is limited, so timely watering is essential to maintain the normal water requirements of tree peonies. After potting, water thoroughly once immediately. Afterward, water once every 3-4 days depending on whether the soil is dry or moist, keeping the potting soil moist as appropriate. If too much water is applied and the soil becomes too wet, the branches and leaves are prone to leggy growth, and prolonged wetness or waterlogging can also cause root rot. Especially in summer and autumn, the moisture of the potting soil should be controlled even more, following the principle of not watering until dry. In summer, when dry, water in the early morning or at night; in autumn, as long as it is not too dry, there is no need to water. Excessive moisture causes vigorous buds and autumn growth, and the plant will not bloom the following spring.

Fertilizing

The nutrients in the pot are limited, so timely topdressing is the only way to ensure the normal growth and development of tree peonies. Topdressing can begin in the spring of the second year, using sesame, peanut, or bean cake soaked in water and fermented before use. When applying, dilute with water; during the growing season, apply fertilized water 1-2 times per week. Before flowering and during the flowering period, watering can be done once a day. After the flowers fade, it is best to maintain the plant and apply a light fertilizer or spray fertilizer on the leaves; no topdressing is needed during the winter dormancy period.

Summer and Drainage

Tree peonies dislike prolonged rain, excessive moisture, and intense summer heat. Long periods of high temperature and high humidity can cause leaf scorch and root rot. During the hottest part of midsummer, potted tree peonies can be moved under a seedling shed for shade, or buried together in the soil to prevent heat and lower temperature, while maintaining good drainage and ventilation. When there is no rain, spray water on the branches, leaves, and surrounding area every day to increase air humidity and ensure water supply during the flower bud differentiation period of tree peonies. In the rainy season, pay attention to drainage; on cloudy and rainy days, turn the flower pot upside down to prevent water accumulation in the pot. After flowering, spray 150-times Bordeaux mixture or 800-1000-times thiophanate-methyl solution once every 10-15 days to control leaf diseases. Tree peony roots are sweet and prone to damage by ants or their grubs; they can be killed by watering with a 1000-times dichlorvos solution instead of water.

Pruning and Overwintering

To improve ventilation and light penetration for tree peonies and concentrate nutrients, shaping and pruning should also be done after leaf fall in autumn and winter. Cut off overly dense branches, such as twin branches, crossing branches, inward-growing branches, and pest- or disease-damaged branches, so the plant maintains a beautiful form. In late autumn and early winter, potted tree peonies can be buried in the soil with the branches exposed above the ground, and straw or mounded soil can be used on top to protect them through winter. Some also place the flower pots directly in a cellar to overwinter. In early spring of the following year, remove the covering, take them out of the cellar, place them in a ventilated, sunny spot, strengthen fertilizer and water management, and let them bloom naturally. Some are also placed in a greenhouse or plastic tunnel to force early flowering according to holiday needs. To make potted tree peonies more elegant and classically refined in decorative styling, when the flowers are about to open, a painted pottery or porcelain pot can be placed outside the original clay pot; placing it on a refined pot stand or table in a spacious, bright hall or main room can better reflect the noble beauty of the tree peony.

According to other relevant sources, spraying potted tree peonies with a 1% silver thiosulfate solution before they bloom can reduce bud drop by 55% and extend the flowering period by 1/5 of the number of days.