Cacti have special light requirements, unlike other indoor plants, there is never much light for cacti. True, some cacti require direct sunlight, while others require bright intense, but scattered.
Some species of cactus need direct sun all the time, even during the hottest hours of the day, some species require shading between 12 and 15 hours on sunny summer days in the form of a light net. If the day was not sunny, the grid should be removed. This has its own complexity, since from morning to noon the cactus should be in intense lighting, and when the sun starts to bake at lunchtime, you need to arrange shading. As soon as the rays weaken slightly, the shade is removed. All this refers to the option when cacti stand on the south window. On the west and east windows, shading is generally not required.
Starting in September, sometimes earlier, shading is not needed even on the south window, the sun is already low enough, the days are shortened. The winter sun never leaves burns on cacti, and if there is no cold wintering, then the sun is sorely lacking.
Placing cacti on the window is very important: pay attention to the photo, such a statement steals the light from the plants, all the light passes through the tops, the main part of the cacti does not catch the sun, because the frame closes it. You need to raise the cacti on the stand so that the whole body of the cactus is well lit.
In natural conditions, in autumn and winter with a natural decrease in the intensity and duration of the sun, the air temperature drops, and stays slightly above zero. All life processes in the cactus organism freeze, it goes into a state of rest. In spring, with the lengthening of daylight hours and the simultaneous onset of warm days, cacti resume growth, often blooming simultaneously.
Our pets expect the same conditions from us. They need a cold period of rest! If you do not rearrange them in a cooler room (from + 5 to + 15 ° C for different species), then cacti will continue to grow, if you do not maintain lighting at the appropriate level, their stems stretch, tilt to one side - stretch to the light, and disfigure. Many cacti without a winter dormant period for 3-4 months never bloom.
The photo shows how I placed cacti on glass shelves. Three sheets of glass of the same size are suspended at different heights on twines, which are fixed by hooks in a wooden frame or above a window opening (anchor hooks). This way you can place the pots as close to the glass as possible, plus the glass shelves steal less light. If the pots stood on the windowsill, then they would have to be lined up in rows, and those that would be in distant rows would receive less light.
Signs of lack of light
If the top of the cactus begins to stretch and thin, then it lacks light. I brought such a freak from one computer class. The undulating body of the cactus shows that at times the sun fell on him - in these happy times his body developed in width. But then the poor fellow was again put to the next monitor, far from the window, to catch the "harmful" radiation, and he thinned out words, because in warm room conditions he continued to grow with irrigation.
It is worth remembering that pollution - dust, dirt and rain stains greatly delay lighting. You need to wash the glass several times a year both from the inside and from the outside, because even after spraying the plants with clean boiled water, stains remain on the glass.
Sign of excess sun
There are also cacti, though there are not many of them that cannot tolerate the sun's rays in a wider range of the day - they need shading from 11 to 17 hours - these are mainly epiphytes and half-epiphytes (Ripsalis, Schlumberger, Epiphyllums). But this rule applies in central Russia for the period from March to August, and from about September to February the direct sun does not threaten them.
Any cacti need shading if they have just been transplanted (within a week - two) and when the cacti are sick. In the spring, after a long winter, stingy with sunny days, cacti must be accustomed to the bright sun gradually.
If the sunlight is too intense, the stem of the cactus, its skin acquires a reddish or slightly purple tint. It looks like a tan and is not a permanent defect. If you switch the cactus to more diffused light, the redness will disappear. But in forest cacti (epiphyllums or Decembrists), from an excess of direct sun, the stems initially turn red, but if not shaded, burns can form - oblong dry spots, usually whitish or gray. This usually happens on southwest windows.
If a tan appears on cacti, this is generally not even a reason to create shade, it all depends on the type of cactus and its requirements. Many cacti in nature under the scorching rays of the sun not only blush, but slightly shrivel, but at the same time bloom wildly, literally strewn with flowers.
It is better to use a mosquito net or organza as a shade. If you have cacti located on the south window, which is not shaded by anything from the street, then you can pull a rope along the glass (as is usually done in kitchens) and hang a piece of tulle. If you leave for work and see that the day will be hot, then curtain the window in the morning.
Artificial lighting of cacti
Oddly enough, children of deserts can be grown even completely under artificial lighting. Of course, this is an extreme case when you really want to raise prickly pets, and the windows are either very dark (northern, shaded with trees from the street, first floor) or at work, where there are no windows at all. But usually in such conditions, additional illumination is required all year round in winter and summer, only the intensity depends on the temperature: the cooler the content in winter, the less need for additional illumination.
If you are going to grow cacti from seeds, then you cannot do without additional light - so that the seedlings do not stretch, they need a lot of light.
What lamps to use to artificially light cacti
Plants need light of a certain spectrum, not at all what we see. The rays of the blue spectrum are needed for the growth and development of roots and greenery, orange-red - for the development of leaves and flowering. It is on this fact that special phytolamps are designed. There are fluorescent phytolamps, there are LED ones. The difference in power consumption is that LEDs spend less, but lamps are much more expensive than everyone else.
Craftsmen versed in electronics, able to construct additional light for their plants on their own. They make lamps by connecting blue and red LEDs, collect metal halogen lamps. But what about mere mortals who think nothing of electrics? We act simply - we buy ordinary fluorescent lamps. Now such lamps are available with the usual base Ye27, with a narrow base E 14. But we need lamps with an improved (above average) color rendering index. Such Russian nomenclature of LBC, on European lamps, the designation is 865 color of light. It is designated as follows: "Color: daily Deluxe 865" or "Color code: 865 (Color temperature 6500K)."
Among the people, such lamps are affectionately called lumps. So, the main thing is that the manholes are effective - this is a sufficient number of lamps. The distance to the tops of cacti or seedlings is no more than 5-7 cm, otherwise the cacti will stretch. The distance between the lamps depends on the shape of the lamp. If under an ordinary cartridge, then after about 20-30 cm, depending on the power, if the tubes, then the distance between in parallel is 5-7 cm. To increase the efficiency of the lamps, reflectors can be made. For example, instead of a cardboard lamp shade, bend the collar and glue it with foil on the inside.
Fresh air for cacti
Fresh air is much more important for cacti than for most other plants. Many cacti may not bloom just because they lack fresh air. Therefore, for the summer it is better to place them on the balcony or veranda. At the same time, it is necessary to ensure that they are protected from dust, wind and rain. If the balcony is glazed, then the cacti are provided with shelter and fresh air, and if not, then you can make a canopy over the shelf with cacti from light-transmitting material, for example, from greenhouse film.
- If there are many cacti, then it is best to make pots for one common tray, so they are easier to carry. Ideally, it would be good to gradually accustom cacti to the street, and leave them until the end of summer and even until the beginning of autumn around the clock in the fresh air. Accustoming cacti to night temperature drops helps to strengthen the skin on the plant stem, the hardening procedure prepares it for cold wintering. Such cacti are distinguished by shiny spines, bloom better and easier and have greater resistance to disease. However, with all the love of cacti for fresh air, drafts for them can be disastrous.
When there is no balcony or veranda, you still need to find a way to provide cacti with as much fresh air as possible. If possible, keep the window or window open, while avoiding cold drafts.
Of course, if you have patience and artisan hands, you can make a window shelf. I.e. attach something to the windowsill from the street that you could put trays of cactus pots on. You can assemble a low wooden box to the size of the windowsill and fix it firmly. True, in addition, you will have to take care of shelter in case of rain or strong winds.