The growth factors – The light – part 2

Light has a direct effect on growth, namely, it inhibits elongation growth. Heavily exposed plants have significantly reduced dimensions compared to those, that grew in the shade. The color of the leaves and bulbs shows a lack of light and an excess of light. Soft, dark green parts of the plant develop if the exposure is too low. Excessive exposure to light often results in a reddish color of the leaves. The entire habit of the plant is shaped by light; short, compressed growth occurs with strong exposure and softer, looser, extremely horny growth with severe lack of light.

The question immediately arises here, how the light requirements of an orchid as well as other plants can be recognized. The orchid friend will be at a loss, if he – accepted – owns a kind, whose name he doesn't know, for which he cannot find any advice in the literature. This is indicated in the section “The Environment”, that the outside of the plant gives some clues. Generally one can say, that serious mistakes are avoided in a partially shaded location. When describing the genera and species, their light requirements are mentioned as a guide. A large part of orchid lovers will no doubt find satisfaction in this, to find the necessary or beneficial level of light in the care itself from personal observation. Science has established approximate readings. In the literature about 6400 to 32000 Lux stated as best suited for orchids. That is a lot of leeway. Not everyone has the option, make appropriate measurements. In general, the values ​​cannot be set. Other environmental factors – like temperature, Moisture and air movement – affect the portable level of exposure significantly, so that one's own experience is decisive.

The seasons also require appropriate consideration. Against the first spring sun, which can often be very intense in clean air, the plants are usually particularly sensitive, because after months of lack of light they are not prepared for sudden abundance. There is sufficient shade during the warm season – especially during the most light-intensive times of the day – almost taken for granted. From around the end of August, the shade is differentiated according to the different light requirements of the genera and species, to promote the completion of shoots and the formation of buds. From the middle to the end of September, any artificial shade appears to be dispensable. However, beware of sunny days, which are still conceivable in this period up to mid-October. Damage to the plants as a result of excessive heating with undamped exposure to the sun can be very painful for the owner. Natural shade from deciduous trees is almost self-regulating. In the seasons with little light, the trees are bare, the leaf development and the fall of leaves largely correspond to the need for shading. However, the sun exposure can be too strong before the leaves start to shoot.

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