Light mode for indoor plants
The correct light mode is not just the level of illumination necessary for a plant. This concept includes two more points on which the life of the plant depends.
The length of daylight is approximately the same for all types of plants - for active growth, 12-16 hours a day of natural or sufficiently bright artificial lighting are needed. A shorter daylight hours slows down photosynthesis, so bright winter days do not violate the dormancy period of decorative deciduous plants.
The required light intensity is a variable value, it depends on the type of plant. Some plants develop beautifully on the sunny windowsill and quickly wither away in a dark corner; others feel good in partial shade, but do not withstand direct sunlight.
The human eye is very poorly adapted to measure light intensity. As you move from a sunny window to the corner of the room, you walk only 2.5 meters and move from the direct sunlight into the shadow. Standing with your back to the window, you do not notice a strong difference, however, the light intensity at a distance of several tens of centimeters decreased by more than 95%.
© KLPA (Joshua Kulpa)
Danger Signals: Lack of Light
- Leaves are smaller and paler than usual.
- Lack of growth or elongated stems with very long internodes
- Variegated leaves turn green
- Small flowers or their absence in flowering species
- Lower leaves turn yellow, dry and fall
Hazard Signals: Excess Light
- Faded leaves
- Brown or gray burn spots
- Leaves fall down during the day
- Leaves of shade-loving plants shrink and die
White or cream walls and ceiling reflect light in a poorly lit room, which improves plant conditions. If the plant is in the back of the room with white walls, then it is less inclined towards the window.
In a plant located on the windowsill, leaves and stems stretch to the window. To prevent curvature of the stem, the pot should be rotated from time to time, a little each time. Do not turn the pot when buds form on the plant.
A flowering plant will suffer if it is moved from a place with a recommended light level to a shady one. The number and quality of flowers strongly depend on both the duration of daylight hours and the intensity of illumination. Without sufficient lighting, the leaves will not suffer, but flowering will not be plentiful and long or the quality of the flowers will deteriorate.
In winter, plants are moved closer to the window if possible. This helps to increase daylight hours and the intensity of light entering the leaves.
Keep your window clean in winter - with clean glass, the light intensity increases by 10%.
You should not transfer the plant from a shady place immediately to the sunny windowsill or to the open air; it must be gradually accustomed to brighter light.
A decorative foliage indoor plant can be transferred without any adverse effects from conditions ideally suited to a shady place. It will not die, but it will not feel particularly good either - try to transfer it to a brighter place for about a week every 1-2 months so that it restores strength.
Almost all plants should be shaded from the midday summer sun; if this is not done, then first of all the young unfolding leaflets will suffer.
© Avia Venefica
Rules for observing the light regime
Ornamental leaves require bright diffused light; many of them also tolerate partial shade. Plants with variegated leaves need more light than with green ones; flowering plants, as a rule, require a certain amount of direct sunlight. The most photophilous are cacti and other succulents. There are many exceptions to these rules, so you need to know more about the lighting requirements of specific plants.
The use of artificial lighting in indoor floriculture provides two new possibilities - to grow flowering and decorative-deciduous indoor plants in dark rooms and even in closets, as well as to increase the duration and intensity of natural light in winter so that the plants do not stop growing. For example, uzambar violets with artificial lighting can bloom almost the whole year.
For such purposes, ordinary light bulbs are not suitable - the leaves suffer from the heat generated by them. Instead, artificial illumination is used, as a rule, using fluorescent lamps in the form of long tubes for this. In countries where the cultivation of indoor flowers with artificial illumination is common, many special devices can be found on sale. In Britain, such lamps are usually made at home.
The luminaire consists of one or more tubes under the reflector. The whole structure can be fixed above the plants at a certain height or suspended so that its height can change. The plant should be placed on a pebble tray. 2 W should fall on 1 dm2 of area - this corresponds to the level of illumination in a shady place in the open air in summer. Watch the appearance of plants. Traces of burns on the leaves mean that the lamps are suspended too low. Elongated stems and pale leaves indicate that the light source is too far away. Most often, with artificial illumination, colorful and compact plants are grown, for example, begonias, bromeliads, gloxinia, orchids, peperomia, senpolia and cineraria.
Direct sun: Brightly lit place no further than half a meter from the south window
- Only a few indoor plants can tolerate the scorching sun - only cacti and other succulents living in the desert, as well as pelargonium, can do without shading in the summer months. There are many more plants that require shading from the hot midday sun
Some direct sunlight: A brightly lit place where some direct sunlight falls during the day.
- Window sill of the western or eastern window, a place nearby (but not closer than 50 cm) from the southern window or window sill of a slightly shaded southern window. This is the best place for many flowering and some decorative foliage indoor plants.
Bright diffused light: A place where direct sunlight does not fall, not far from a sun window
- Many plants feel best in such lighting, which happens to be within about 1.5 m of the sun's window. Similar conditions on a wide, sun-shaded window sill.
Penumbra: A place with moderate lighting within 1.5-2.5 m from a solar window or near a window not illuminated by the sun
- Very few decorative-flowering plants feel good in such conditions, but they are quite suitable for many decorative-deciduous plants. Most plants with bright, but not withstanding direct sunlight foliage can adapt to such conditions.
Shadow: A poorly lit place, but enough light to read a newspaper for several hours a day
- Only a few of the decorative-deciduous plants successfully grow in such conditions - these include aglaonema, aspidistra, asplenium. However, many plants from the previous group can adapt to this level of illumination. Decorative-flowering plants under such illumination will not bloom.
- No houseplant can live in such conditions.
- D. G. Hessayon - The house plant expert (Dr. D. G. Hession - All About Indoor Plants)