The objective assessment of plants and their light requireme

[talha.bin.ayub]

Of all of the factors affecting plant growth in interiors, adequate light is by far the most important. Light is needed for plants to produce food and survive — generally, the more light available, the more food produced for growth. Light is measured in units called foot candles. One footcandle (ft-c) is the amount of light cast by a candle on a white surface 1 foot away in a completely dark room. Outdoors, the light levels on a bright day range from 10,000 ft-c in an open sunny area to 250 ft-c or less in the shade of a large tree.
It is very helpful to have a general idea of how much light is present in a given location in your house. You can get a fairly good estimate with a handheld light meter, or you can use a 35 mm camera and do the following:
Set the film speed indicator to ASA 25 and the shutter speed to 1/60th second.
Place a piece of white paper where you want to measure the light levels, aim the camera toward the paper close enough to fill the view, and adjust the f/stop so that the meter indicates a correct exposure.
Read the approximate light level from Table 1.
Table 1. Indoor light levels and appropriate f/stop settings
f/stop Setting Light Level
f/2 40 ft-c
f/2 75 ft-c
f/4 150 ft-c
f/5.6 300 ft-c
f/8 600 ft-c
f/11 1,200 ft-c
f/16 2,400 ft-c
With the help of this table, you can obtain the light intensity reading from anywhere in your home. For example, if the f/stop setting is f/16, the approximate light level is 2,400 ft-c.
Using the light readings, your home can be divided into four areas, which have the following light levels for 8 hours per day:
Low-light areas: 25 ft-c – 75 ft-c
Medium-light areas: 75 ft-c – 200 ft-c
High-light areas: over 200 ft-c but not direct sunlight
Sunny light areas: at least 4 hours of direct sunlight


Sent from TBA iPhone using Tapatalk

[talha.bin.ayub]

In your home, the amount of light in a given location is variable — it is affected by the presence of trees outdoors (may shade at certain times), roof overhangs (may shade at certain times), wall color (reflectance), window curtains, day length, time of day, and time of year.
When shopping for indoor plants, select plants for a given location based on the approximate light levels in the spot. The plant’s label will usually contain information on the light requirements of the plant. If the plant label lists “high light” but the selected area in the home does not provide adequate light, artificial light sources such as fluorescent and/or special incandescent lights may be used to supplement the natural light.
Increasing the number of hours of light exposure can also help—for example, 16 hours of light and 8 hours of dark. This extends the number of hours during which plants receive light.
While adequate light is crucial for plant growth, too much light can be damaging (Figure 1).
Indoor plants are classified according to the amount of light needed for growth. (A list of plants and their light requirements is provided in Table 3.) Look for this information in general terms on the plant’s label:
Low: minimum 25 ft-c – 75 ft-c, 75ft-c – 200 ft-c for good growth
Medium: minimum 75 ft-c – 150 ft-c, 200 ft-c – 500 ft-c preferred
High: minimum 150 ft-c – 1,000 ft-c, 500 ft-c – 1,000 ft-c preferred
Very high: minimum 1,000 ft-c, 1,000+ ft-c preferred
Windows with eastern exposure within the home generally provide the best light and temperature conditions for most indoor plant growth because plants receive direct morning light from sunrise until nearly midday. Footcandle readings at these windows can reach 5,000-8,000. As the morning progresses, the direct sun recedes from the room.
An eastern room is cooler than southern or western rooms because the house absorbs less radiant heat. Light from the east is cooler than that from the south or the west, and thus it causes less water loss from the plants.
Windows with southern exposure give the largest variation of light and temperature conditions. The low winter sun shines across the room for most of the daylight hours.
In the summer, when the sun is farther north than it is in the winter, the sun rises at a sharp angle in the morning and is high in the sky by noon. Direct light comes into a south window only at midday. If there is a wide overhang covering the windows outside, the sun may not enter the room at all. The sun at noon on a summer day may measure 10,000 ft-c. Indoors, however, a southern window with wide eaves on the outside will receive about the same amount of light as a window with northern exposure. Southern and western exposures are interchangeable for most plants. In the winter, most plants, except those with definite preference for northern exposure, can be placed in a room with southern exposure.
Windows with northern exposure provide the least light and the lowest temperature. Because the United States is in the northern hemisphere, it receives most of its sunlight from the south. Out of the four exposures, the northern exposure receives the least light and heat year round.


Sent from TBA iPhone using Tapatalk

[talha.bin.ayub]

ImageUploadedByTapatalk1452657790.031952.jpg (42.36 KiB) Viewed 5322 times

Within your home, changes in natural light penetration occur with the seasons.


Sent from TBA iPhone using Tapatalk

[talha.bin.ayub]

Because of the low-light levels, maintaining healthy plants can be a challenge. A northern windowsill can measure light levels as low as 200 ft-c on a clear winter day, which is optimal for some plants, such as the African violet. This exposure is best for plants with green foliage because the coloration on variegated foliage tends to disappear under low-light conditions. Although most plants grown indoors will not grow in a northern room, they may tolerate it for short periods of time.
Seasons change the amount of natural light entering through windows. For example, the summer sun reaches a higher zenith compared to the winter sun (Figure 2). Therefore, sunlight penetrates farther into a room during winter.
How can you tell if your plant is not receiving adequate light?
The plant does not grow.
The internodes (spaces between the leaves) on the new growth are much longer than the internodes on the older part of the plant.
The new leaves are smaller than the older leaves.
The leaf color is a lighter green on the newer foliage than on the older foliage.
The older leaves are dead.


Sent from TBA iPhone using Tapatalk

[talha.bin.ayub]

ACCLIMITISATION:

ImageUploadedByTapatalk1452658031.073990.jpg (40.48 KiB) Viewed 5320 times

The two sides of acclimatization — the above-ground (light acclimatization) involves adaptation to low light, which means less growth and less need for nutrients. The below-ground (soil acclimatization) involves reduction of nutrients and water.


Sent from TBA iPhone using Tapatalk

[talha.bin.ayub]

Acclimatization is the adaptation of a plant to a new environment, and it is very important for the health and growth of indoor plants. In greenhouses, plants are accustomed to high light, nutrition, water supply, temperatures, and relative humidity — conditions ideal for fast growth (Figure 6). Residential homes, with low-light interiors and low relative humidity, will most likely produce a stressful experience for plants — the greater the difference between the previous environment and the environment of the house, the greater the stress the plant endures.
Acclimatization is generally done in the greenhouse or the nursery. Plants are grown for a period of time under low-light levels and with fewer nutrients. Because this slows down plant growth, acclimatized plants are not ready for the market as early as nonacclimatized plants. Acclimatized plants cost more compared to nonacclimatized plants, but this is money well spent. Figure 7 and Table 2 describe the symptoms and appearance of acclimatized plants.
To acclimatize plants at home, place newly purchased plants in bright areas for at least 3 to 4 weeks and then move them to their final location. Porches and patios are ideal bright places for your plants in the warm months, as long as the plants are not in direct sunlight. The most common symptom occurring in plants placed indoors is defoliation. As long as it is not extensive and it slows down after a few weeks, the plants will adjust to the particular location. Keep in mind, however, that each time the plant is moved around, it will experience an acclimatization period, and such changes may become evident.
Learn as much as possible about the extent of acclimatization of the chosen plants. The retailer should be able to provide this information. When shopping for plants at a garden center, ask if the plants have been acclimatized.
Remember that the most important factors of indoor plant growth are adequate light, fertilizer, and water at reduced rates.


Sent from TBA iPhone using Tapatalk

[talha.bin.ayub]

Light and Moisture Requirements For Selected Indoor Plants:

https://www.uaex.edu/yard-garden/home-l ... ements.pdf


Sent from TBA iPhone using Tapatalk

[talha.bin.ayub]

http://msucares.com/pubs/publications/p1012.pdf


Sent from TBA iPhone using Tapatalk

[talha.bin.ayub]

http://extension.missouri.edu/p/G6515


Sent from TBA iPhone using Tapatalk

[talha.bin.ayub]

http://polk.ifas.ufl.edu/hort/Power%20P ... Plants.pdf


Sent from TBA iPhone using Tapatalk