Perennials exhibit robust growth with stronger roots compared to annuals or biennials, penetrating deeper into the soil and boasting enhanced drought resistance and adaptability to adverse environments. Once planted, they can continue to bloom for many years.
When planting, it's essential to deeply till the soil and apply ample organic fertilizers to ensure good soil conditions for a longer period. Perennials require well-draining soil. Additionally, different growth-stage perennials have varying soil requirements; generally, they prefer loamy soil rich in humus during the seedling stage, while after two years, clayey loam is more suitable.
Root plants come in a variety of species, and different propagation methods can be employed depending on the category. Species that produce good seeds and can bloom within one to two years after sowing, such as Chinese mallow, Platycodon grandiflorus, Delphinium grandiflorum, and Chrysanthemum coccineum, are commonly propagated through seeds. The propagation period varies by species; those that bloom in summer and autumn and hibernate in winter are sown in spring, while those that bloom in spring and hibernate in summer are sown in autumn. Some species, like chrysanthemums, peonies, hostas, daylilies, bellflowers, and irises, often bloom without producing many seeds or not at all, but have strong sprouting capabilities; for these, propagation by division is used. The timing of division depends on blooming period and cold tolerance; those with strong cold tolerance and blooming in spring can be divided in autumn, while species like Acorus gramineus and Sempervivum can be divided in both spring and autumn. Some species, such as carnations, chrysanthemums, and amaranth, can often be propagated through stem cuttings.
Perennials require careful watering, fertilizing, and weeding during the seedling stage, but the management becomes relatively simple after planting. To promote lush growth, abundant flowers, and large blooms, apply a top dressing when new shoots emerge in spring, followed by another application before and after the flowering period. In autumn, when the leaves begin to wither, you can apply well-composted manure or compost around the base of the plants.
Root plants come in a wide variety, with significant differences in their adaptability to soil and environment. Some prefer clayey soil, while others thrive in sandy loam. Some require ample sunlight for optimal growth, while others are shade-tolerant. When planting root plants, it's essential to select the appropriate species based on the planting location, such as choosing species with strong adaptability, easy branching, and flowering, like daylilies, irises, and lilies, for planting along walls or roadsides; opting for sun-loving, large-flowered, and vibrant species like chrysanthemums, peonies, and delphiniums for flower beds and borders at park entrances; planting plants like hostas and evergreens under trees or in sparse forests; and using plants like malva and Platycodon for roadside and沟side landscaping.
Perennials bloom continuously after planting, to maintain their full and robust shape and achieve the goal of year-round flowering, different pruning techniques are employed based on their categories. During transplantation, to balance the root system with the above-ground parts, and sometimes to inhibit excessive growth of foliage, promoting flower bud formation, a portion of either the above-ground or underground parts can be trimmed based on the specific situation. For perennials that flower for many years and grow too tall with a noticeable hollow at the base, pinching should be done. Sometimes, to increase the number of lateral branches and encourage more flowers, pinching is also performed, as in the case of carnations and chrysanthemums, etc. Generally, pinching has a certain inhibitory effect on plant growth and development, so the frequency of pinching should not be excessive for a single plant and should not be done simultaneously with potting or repotting. Pinching typically involves only the growth point, and sometimes a few young leaves can be included, but the amount of pinching should not be too extensive.