At present, people's requirements for living environment are no longer just basic living needs. "Green home decoration" and returning to nature have become new goals that people pursue. Therefore, it is particularly important to use the characteristics of plants to turn limited indoor and outdoor spaces into "green spaces". This article starts with plant ecological types and discusses the application of garden plants in indoor areas.

1 Ecological types of garden plants

1.1 Light intensity ecological type

1.1.1 Light-loving plants

Plants that love light but cannot tolerate shade will not grow well in low light conditions, such as ginkgo, metasequoia, tamarisk, albizzia, acacia, poplar, willow, papaya, pomegranate, tulip tree, begonia, crape myrtle, bauhinia, plum blossom, locust, white jasmine, Michelia, poinsettia, winter jasmine, forsythia, hibiscus, rose, rose, cypress, etc. in woody plants; peony, cineraria, chrysanthemum, five-color pepper, clover, asparagus, lucky grass, globe amaranth, strelitzia, sunflower, carnation, sunflower, gladiolus, aster, etc. in herbaceous plants.

1.1.2 Shade-tolerant plants

It has strong shade tolerance. Most shade plants grow in shaded areas. For example, woody plants include spruce, Podocarpus, hydrangea, Torreya grandis, azalea, holly, snow willow, daphne, hydrangea, snow lily, mosquito tree, pittosporum, bamboo, and palm bamboo; herbaceous plants include centipede grass, peperomia, dieffenbachia, asparagus fern, spider plant, spider plant, monstera, hosta, and Lycoris radiata.

1.2 Light length ecotype

1.2.1 Long-day plants

Long-day plants refer to plants that can only bloom when the length of daylight exceeds the critical day length, that is, plants that can only bloom when the length of daylight is greater than a certain number of hours (this number of hours is called the critical day length). Such plants include apples, plum blossoms, peach blossoms, mountain peaches, elmleaf plums, lilacs, forsythia, geraniums, gloxinia, orchids, Euphorbia pulcherrima, fuchsia, gladiolus, Mirabilis jalapa, bellflowers, and cattail flowers.

1.2.2 Short-day plants

Short-day plants refer to plants that can only bloom when the length of daylight is shorter than their critical day length, such as poinsettia, chrysanthemum, Christmas cactus, bromeliad, salvia, hibiscus, bougainvillea, Clivia, etc.

1.3 Temperature Ecotype

1.3.1 Wide-temperature plants

Wide-temperature plants can adapt to larger temperature fluctuations. For example, pine, birch and oak can adapt to a temperature range of -5 to 55°C.

1.3.2 Narrow temperature plants

Narrow temperature plants have relatively strict temperature requirements and can only adapt to a very narrow temperature range. Narrow temperature plants are divided into high temperature narrow temperature plants and low temperature narrow temperature plants. The former can only grow and develop under high temperature conditions and are most afraid of low temperatures, such as coconuts and cocoa, while the latter can only grow and develop within a low temperature range and are most afraid of high temperatures, such as Pinus tabulaeformis and Larix gmelinii.

1.4 Water Ecological Type

1.4.1 Xerophytes

They are adapted to grow in arid environments, can endure drought for a long time, and have the characteristics of adapting to arid environments in morphology and physiology. For example, the leaves of Taiwan Acacia, Coral Tree, Tamarix, and Casuarina degenerate into scales or hairs; the leaves of Feather Grass curl into a tube; the leaves of cactus become needle-shaped; these changes are conducive to reducing transpiration. Plants such as aloe, cactus, and Sedum have a large amount of parenchyma tissue, which can store a lot of water. In particularly dry seasons, Salsola can survive adversity by dormancy and grow again after rainfall. Some leaves have wax film; some stems and leaves have white epidermal hairs, which are conducive to reflecting sunlight; some have high intracellular osmotic pressure, and some have very developed root systems, which are conducive to active water absorption. There are unique xerophytes in deserts, rock walls, frozen soil, acid marshes and salinized soils.

1.4.2 Aquatic plants

Wet plants are those that grow in a humid environment and cannot tolerate a lack of water for a long time. According to the characteristics of the environment in which wet plants live, they can be divided into two categories: shade-loving wet plants such as calla lilies, asteraceae, various epiphytic ferns and epiphytic orchids in the forest. They generally grow on trees in the humid air (epiphytic); sun-loving wet plants such as some species of Cyperaceae, Polygonaceae and Cruciferae. They generally live in swamps or lakeside areas with plenty of sunlight and saturated soil.

1.5 pH Ecological Type

1.5.1 Garden plants for acidic soil

Garden plants that grow well in acidic soil with a pH value below 6.5 include bromeliads, ferns, orchids, Masson pine, gardenia, camellia, azalea, etc.

1.5.2 Garden plants for alkaline soil

Garden plants that can tolerate alkaline soil with a pH value of 7.5 or above, such as herbaceous flowers such as dianthus, gerbera, geranium, etc.; woody plants include white pine, tamarisk, cypress, broad-leaved fraxinus, small-leaved fraxinus, poplar, torch tree, Taiwan acacia, soapberry, poplar, mulberry tree, silver poplar, Amorpha fruticosa, Elaeagnus sorbifolia, Prunus armeniaca, Prunus barbata, magnolia vine, peony, ailanthus, elm, chinaberry, mulberry, etc.

1.6 Nutritional Ecotype

1.6.1 Plants that are intolerant to barrenness

This type of plant has strict nutrient requirements and requires fertile soil. Any slight lack of nutrition will affect its growth and development. Such as most of the annual and biennial herbaceous flowers and woody plants such as Metasequoia, Armand pine, cypress, fir, red pine, golden pine, cedar, horse chestnut, Ligustrum lucidum, cherry, osmanthus, Chinese tallow tree, laurel, magnolia, pomegranate, four-orange tree, white jasmine, holly, plum, plum blossom, mango, lamp tree, eucommia, willow, weeping willow, sycamore, ginkgo, paulownia, walnut, toon, crabapple, orange, magnolia, magnolia, purple magnolia, banyan tree, tulip tree, crape myrtle, Sophora japonica, small-leaved banyan, camphor, horse chestnut, Mahonia, Serissa chinensis, maple, rose, fig, camellia, dogwood, red yew, azalea, Hypericum, peony, Michelia, Prunus mume, jasmine, hydrangea, boxwood, osmanthus, Nandina domestica, gardenia, witch hazel, elderberry, daphne, osmanthus, osmanthus fragrans, wintersweet, and peach.

1.6.2 Plants that tolerate barrenness

They do not have too strict requirements on the nutrients in the soil and can adapt to soils with low nutrient content. Commonly used barren-resistant woody plants in greening include spirea, thyme, dwarf crape myrtle, Amorpha fruticosa, honeysuckle, yellow fir, wolfberry, sedum, palm, lilac, masson pine, ivy, hibiscus, pyracantha, bougainvillea, forsythia, red flower honeysuckle, honeysuckle, persimmon, Ailanthus altissima, rhus chinensis, Koelreuteria paniculata, mulberry, cotinus coggygria, Pistacia chinensis, chinaberry, elm, casuarina, masson pine, Chinese pine, cypress, Fujian cypress, poplar, hawthorn, poinciana, torch tree, Xanthoceras sorbifolia, heather, birch, ash, albizia, bauhinia, apricot, locust, jujube, paper mulberry, castanopsis bittersweet, Lespedeza, papaya, tassel, vitex, yellow thorn, plum, deutzia, Amorpha fruticosa, Caragana, tea tree, etc.

2. Selection of indoor and outdoor green plants

2.1 Selection of green plants in residential areas

The primary principle for selecting plant species in residential areas is that they are beneficial to the physical and mental health of residents, or at least harmless to the human body. Specifically, it is necessary to select plant species that are non-flying, non-toxic, non-irritating, and non-polluting. Plants with thorns, such as roses and yellow roses, should be avoided as much as possible in places where children can easily touch them. It is very meaningful for residential areas to select suitable resistant plants according to the local pollution conditions to purify the air.

Plants with various protective functions should be appropriately adopted, especially those with multiple functions. Plants in residential areas should have a protective effect on the environment. For example, fire-resistant plants such as ginkgo, palm, and banyan trees; strong dust-retaining plants such as elm, Chinese kite, and hibiscus; and strong noise-reducing plants such as sycamore, weeping willow, and spruce.

In addition, attention should be paid to biological diversity. On the basis of meeting the above requirements, increasing the number of plant species as much as possible and selecting different types of plants can better maintain the ecological balance of the plant community and increase the ornamental effect and ecological function of the plant community.

2.2 Selection of outdoor wall greening plants

One third of the courtyards in front of and behind the house are in the shade of the house, so be sure to choose shade-tolerant plants such as weeping crabapple, golden and silverwood, pearl bush, etc. Wall greening is mostly some vines, or shrubs for viewing flowers and fruits that have been shaped, pruned and tied, and very few trees, supplemented by various bulbous and perennial flowers as basic plantings, commonly used species such as wisteria, wood fragrance, climbing roses, ground ivy, five-leaf ground ivy, kiwi, grapes, clematis, American trumpet creeper, trumpet creeper, honeysuckle, disk-leaved honeysuckle, schisandra chinensis, schisandra chinensis, plain square flower, ground wind, chicken blood vine, bird of paradise, green radish, cliff horn vine, passion flower, firecracker flower, quisqualis, winter jasmine, forsythia, pyracantha, ginkgo, magnolia, etc.

2.3 Selection of roof greening plants

The roof is hot and dry in summer; it is cold, windy and dusty in winter. The subsoil in the roof garden is relatively thin, which means that when choosing plants, we should choose plants that are drought-resistant, low-temperature-resistant, have short taproots, well-developed and plump fibrous roots, are resistant to barrenness and strong in wind resistance. Try to use native plants as much as possible. The plant configuration should be reasonable, with a beautiful view all year round and each with its own characteristics. Consider shade-tolerant tree species, and fully consider the biological characteristics of plants without violating the design. Shallow roof gardens are generally dominated by lawns, with color bands in between, and rarely planted with flowering shrubs and large trees with large root systems. Deep roof gardens can be configured with flowering shrubs and trees. When configuring plants, we must fully consider the later effects and the influence of the root system on the laying materials. When selecting plants, we must base our selection on the above requirements and choose suitable plants. The plant configuration should not be too complicated, but should be concise and clear. Commonly used plant species include roses, plums, roses, boxwood, pomegranates; wisteria, trumpet creeper, clover, ivy, grapes, honeysuckle; apples, strawberries, green peppers, kumquats; herbs and perennial flowers.

3. Choice of indoor green plants

Indoor lighting is relatively weaker than outdoor lighting, mostly scattered light or artificial lighting, and lacks direct sunlight; however, the indoor temperature is relatively stable, with small annual and daily temperature differences, and there may be air conditioning for heating and cooling; the indoor air is relatively dry, and the humidity is lower than outdoors; the indoor carbon dioxide concentration is higher than outdoors, and the ventilation and air permeability are poor.

The indoor space is relatively closed. In order to achieve the best "green decoration" effect in a leisure space, we must first consider the characteristics of the indoor environment, and secondly obey the nature and purpose of the indoor space, consider making full use of the walls, ceilings, and floors to select plant materials, and at the same time take into account the ornamental and ecological habits of the plant materials to unify aesthetics and ecology.

3.1 Consider the indoor lighting conditions

The main ecological factor that limits plant growth indoors is light. If the light intensity does not reach the light compensation point, the plant will grow weak or even die. If the light is too long or too short, it is also not conducive to the growth and development of plants. The light conditions of the east, west, south and north windows are different, so you need to be selective when configuring plants, see Table 1.

Table 1 Lighting characteristics and plant selection at different locations indoors

3.2 Consider indoor temperature and humidity conditions

Generally speaking, indoor temperature and humidity are required to be maintained within a certain range. The effective growth temperature of plants is preferably 18-24℃, and it is better to be above 10℃ at night. Too high or too low temperature will affect plant growth. The most difficult thing to maintain is indoor humidity. If the environment is dry and cold, the plants will grow slowly or even die. Only a few plants such as the golden plate can adapt. The tropical or subtropical plants that are now popular in indoor configurations require high temperature and high humidity environmental conditions. While maintaining the appropriate temperature, the pots are placed on a plate of wet peat or water to increase the humidity. Especially for plants growing in tropical rainforests, it is necessary to keep a humid environment at all times. They must be watered thoroughly once a week, followed by liquid fertilizer to ensure the supply of water and fertilizer.

3.3 Consider the role of indoor plants in purifying the air

Indoor air pollutants include formaldehyde, benzene, ammonia, carbon oxides and some suspended solids. We can use plants to purify air pollution. Ivy, cycads, kumquats, half-branch lotus, roses, camellias, pomegranates, Milan, daisies, wintersweets and marigolds can effectively eliminate harmful substances such as sulfur dioxide, chlorine, ether, ethylene, carbon monoxide and nitrogen peroxide. Orchids, osmanthus, wintersweets and calamus have strong dust absorption capabilities and are natural dust collectors; Monstera, Christmas cactus, cactus and other plants have strong absorption capabilities for carbon dioxide; cacti have strong absorption capabilities for radiation; canna has strong absorption capabilities for sulfur dioxide; silver taro, spider plant, aloe, and tiger tail plant absorb formaldehyde; evergreens and daisies remove trichloroethylene; aloe, spider plant, tiger tail plant, spathiphyllum and monstera are natural scavengers that can remove harmful gases in the air and have strong ability to absorb formaldehyde. For newly renovated houses, indoor pollution is undeniable. These plants can be used to purify the air and monitor the indoor environment.

3.4 Plant selection for different locations

Similarly, in the room, the plants placed in different positions are also different. At the entrance of the room, the light is dim and the space is narrow, so you can put some potted shade-tolerant plants that do not block people's sight, such as bamboo palm, Cyperus rotundus, coconut, cycad, fortune tree, poinsettia, etc., to give people a sense of lively and bright lines. When arranging plants in the living room, strive to be beautiful and generous, not easy to be complicated. Place one or two pots of Boston fern, colorful taro, bamboo palm, Indian rubber tree, cycad, fan palm, banana, etc. on both sides of the sofa. People sitting on the sofa are like being in the embrace of nature. The study room should be equipped with elegant, quiet, bookish and literati style plants. Some evergreen foliage plants such as rubber trees, monstera, king coconut, Brazilian wood, ivy, etc. are often used for stairs, such as asparagus, orchids, Milan, spider plants, etc.; general small and medium-sized foliage plants such as Araucaria, Guangdong Wannianchun, bromeliads, ferns, and pepper grasses can be placed on wooden, plastic or porcelain pedestals, with the background of the pedestals, elegant and pleasing to the eye. Some small foliage plants can be placed on the same shelf to form a group beauty. However, some precious foliage plants can be placed on exquisite and beautifully shaped shelves, and should be placed alone to show the beauty of transcendence. Such as monstera, garroba, etc. The balcony is mainly for decoration. Because there is sufficient light, there are many types of plants to choose from. Common forms of placement include potted flowers, bonsai, hanging plants, etc.