Light bulbs

Sun, 05 Mar 2017 12:39:53 PST

I can confirm the the 3 wavelength LED (Red, orange, blue) are quite 
effective for plant growth, e.g. tomatoes stay compact and freesias grow 
buds  - I've yet to find a plant that is not compatible. I agree that 
those are too irritating for a living room or for enjoying flowers, but 
they do work well for seedlings in my study room next to the computer, 
and for those plants that need light over winter in a small side 
chamber. for me, they are the winner for price-performance ratio plus 
they seem realtively safe since they are "cold".

Am 05.03.2017 um 21:21 schrieb Anita Roselle:
> Leo, I want to thank you for all the information on electric lighting.
> I used lights years ago when the best was 2 different fluorescent bulbs in
> a 2 bulb fixture. I now wish to put some light on my african violets that
> do not get enough light in the winter to bloom. I have been befuddled about
> what to buy as there are so many choices, perhaps all of which I know
> nothing about. You have spelled out for us what the different options are
> and what they do. I now know what I need to look for and be confident that
> I am getting the best light at the best cost. I will look for a 2' compact
> fluorescent fixture with a single high-output T5 bulb. This is at the
> window over my kitchen sink and I don't like the weird light I have now.
> I did purchase from Amazon a clip on light, I wanted the clip, that has a
> whole lot of small bulbs of different colors, I think red and blue, are
> they LED's? They get the plants to bloom but the color is such that the
> blooms to peoples eyes are not true to their real color, in fact they look
> weird.
> Thank again,
> Anita R.
> On Sun, Mar 5, 2017 at 1:45 PM, Leo Martin <> wrote:
>> Norton asked about supplemental lighting for sprouting bulb seedlings
>> indoors.
>> Technology is changing rapidly. In 5-10 years light growers will probably
>> be using LED lights, with only a few holdouts. LED lights are more
>> expensive to buy today, but less expensive over their lifespan when
>> considering the lower electricity usage. I have read analyses suggesting
>> the break-even point is 6 months to 2 years.
>> Light gardeners have abandoned incandescent bulbs. They are inexpensive,
>> but most of the electricity is wasted producing heat. The bulbs do not last
>> long.
>> High-pressure sodium lighting (HPS) is very expensive to buy, uses a lot of
>> electricity, and produces the most heat of any lighting used for
>> horticulture. The lamps are so hot a person would get a third-degree burn
>> from a single touch lasting less than a second. Water on an illuminated
>> lamp - like from a spray bottle - causes an explosion, showering
>> near-molten glass all over the growing area. I would not recommend HPS to
>> any home grower, under any circumstances, because of the heat danger. Much
>> safer and equally effective alternatives exist. This kind of lamp was used
>> for commercial indoor herb growing for years, but these growers have
>> switched to other lighting.
>> Different kinds of fluorescent lighting work well for growing plants, and
>> have been standards for some years. Fluorescent grow lights will be
>> replaced by LEDs over the next few years for reasons of efficiency and
>> lifetime cost. Another problem with fluorescent lights is that they contain
>> mercury, and LEDs contain little or none.
>> Hobbyists used standard fluorescent tubes for years; compact fluorescent
>> lights (CFL) also work well, and use less electricity. Most indoor
>> fluorescent light growers choose long tubes because the fixtures fit better
>> under shelves or over windowsills. Spiral fluorescent lights also work
>> well. When a spiral lamp is used, the long axis of the spiral should point
>> down at the plants, since spiral lamps are designed to emit more light
>> along the axis rather than from the sides. All fluorescent lamps need to be
>> replaced at least every 12 months. Their light output begins decreasing
>> within 6 months, and most are down to 75% or less of the initial output by
>> a year. The human eye does not see this, but the plants do. If you choose
>> to use fluorescent lamps, write the date placed into service on the tube
>> with an indelible marker, and replace every 9-12 months. Standard
>> fluorescent lights are hot, but not as hot as an incandescent bulb. They
>> will cause a burn but most people would remove their hand from the hot tube
>> before serious injury.
>> Long fluorescent tubes are labeled as to the size of the tube. Standard
>> tubes are T8. They can work well for growing plants if wattage and color
>> are chosen correctly. Higher-wattage tubes produce more light, and most
>> people choose 40 Watt T8 tubes rather than 20 W. A very common fixture for
>> light growers is sold as a shop light; it holds two, 4 foot / 122cm long T8
>> tubes. They are easy to suspend underneath shelves. Several can be plugged
>> into a power strip, which can be plugged into a heavy-duty electric timer.
>> Aquarium, terrarium and some plant growers often use high-output T5 tubes
>> (T5HO), which produce more light for the electricity used than standard
>> tubes. T5s are smaller in diameter than T8s and require different fixtures.
>> High-output lamps require different fixtures than standard output. Many
>> indoor growers buy T5HO aquarium light fixtures for their plant stands. The
>> fixtures and tubes are more expensive than standard T8 fixtures and tubes,
>> but when considering the cost of electricity over the life of the fixture
>> they cost less to run than T8s. They are readily available at aquarium
>> shops and online. T5HO fixtures come in different lengths, for different
>> sizes of aquarium, so it may be easier to find a T5HO fixture to fit a
>> small space as compared to T8 fixtures. T5HO tubes are hotter than standard
>> T8 tubes.
>> Fluorescent lights are available in different light colors, which is
>> measured in degrees Kelvin (K.) This is a measure of how the light appears
>> to the human eye, and has nothing to do with the actual Kelvin temperature
>> scale. It also says nothing about the actual frequencies of photons making
>> up the light. It turns out that fluorescent lights with a light color of
>> 6,500 K are good for growing plants, so this is what most people buy. Some
>> manufacturers refer to 6,500 K color temperature as "daylight", but others
>> use "daylight" to refer to other color temperatures. Look for the number on
>> the box or label. Other light colors alone are not as good for growing
>> plants as are 6,500 K. Generally, there is no advantage to adding lamps
>> with other light colors to lamps of 6,500 K. Aquarists can buy 10,000 K
>> high-output T5s, which provide brilliant white light. But, plants don't
>> grow very well under this; it is designed for corals. Many T5HO fixtures
>> are sold with 10,000 K and actinic blue tubes, neither of which works well
>> for plants, so it is better to buy a fixture and tubes separately.
>> LED lights of color temperature 6,500 K are not necessarily the best for
>> growing plants, The usefulness of 6,500 K color temperature applies only to
>> fluorescent lights.
>> Compact fluorescent lamps use less electricity for the light output
>> compared to standard fluorescents, so many light growers are switching. 4
>> foot long CFL tubes fit into some standard 4-foot, 2-tube fixtures, but not
>> all. Some CFL tubes are made to fit into older fixtures, and other need
>> fixtures specifically for CFL tubes. Most spiral CFL lamps fit into older
>> standard socket fixtures. The least-expensive solution if CFL is chosen
>> would be standard 4 foot long shop fixtures, each holding two CFL tubes.
>> Choose 6,500 K color temperature, and the highest Wattage available. Until
>> recently indoor commercial growers used CFL lamps of 6,500 K color
>> temperature at the highest Wattage they could get.
>> LED (Light-Emitting Diode) lighting is still being developed and perfected.
>> Until recently attention was placed on light for human use, and not much on
>> plant growth. So, most knowledge of how LED lighting works for plants has
>> been trial-and-error. LEDs last perhaps 3-5 years when used 12 hours per
>> day. They are more expensive to buy, but use much less electricity than
>> other lamps. Over their life they are less expensive to run.
>> Individual LEDs emit only certain wavelengths of light, and multiple
>> wavelength LEDs are combined to give the desired light color as seen by the
>> eye. Individual LEDs are rectangles about 2 millimeters square. Multiple
>> LEDs are wired into strips or rectangular arrays, and a protective covering
>> usually put over them, to form lamps. LED lamps are available as flexible
>> linear strips, lamps resembling fluorescent tubes, and lamps resembling
>> incandescent bulbs. The tube-like LED lamps require their own fixtures and
>> generally cannot be used in older fluorescent fixtures. The standard-socket
>> LED light bulbs can be fit into older sockets.
>> At first growers tried to match LED wavelength emitted to the known maximum
>> absorption peaks of chlorophyll, which produced ghastly-looking pink and
>> blue light. It has since been realized chlorophyll absorbs and uses other
>> wavelengths quite well, so these pink and blue LEDs are now considered
>> unnecessary. The idea of a "good" LED lamp for plants includes whether
>> proper wavelength photos are emitted. You will read of`a measurement called
>> PAR, photosynthetically active radiation. This measures what proportion of
>> the photons emitted by the LEDs are used by the plants. Recall color
>> temperature measures how the light looks to the human eye. Different
>> combinations of light wavelength can yield what we think is white light.
>> LED color temperature has not been found useful for deciding which lamp to
>> use on plants, so don't go looking for 6,500 K LED lamps. People are also
>> concerned with how many photons are emitted for the electricity input
>> (efficiency.)
>> Not many smaller LED lamps have been designed specifically for plants, so
>> it can be difficult to choose. However, by trial and error, people have
>> reported some lamps work well. In general, most bright white lamps produce
>> acceptable growth. An LED shop light Home Depot sells has been found to
>> work well:
>> White-LED-Chain-Mount-
>> Shoplight-1290L/204378710
>> as have various LED light bulbs designed to be screwed into desk lamp
>> sockets.
>> Commercial indoor growers are switching to LED arrays:
>> and plasma lighting
>> plasma-02-ac-lep/
>> but these are for very valuable crops.
>> So, for Norton... Can you buy in Peru standard T8 fluorescent light tubes
>> and fixtures with 6,500 K color temperature ("daylight"), 20 or 40 Watt?
>> (40W is better.) We know those work well, and will not require importing.
>> This would be your simplest solution. Tubes must be changed once per year.
>> Or, can you buy in Peru T5HO intended for aquariums, with color temperature
>> 6,500 K? Those work well and are more efficient than standard T8. The tubes
>> must be changed once a year.
>> It is hard to carry long, fragile objects on airplanes. Imported CFL tubes
>> only last a year. Imported LED lights will last 3-5 years.
>> People could bring you this light from the US, since it is know to work for
>> plants. It is not as fragile as are fluorescent tubes:
>> White-LED-Chain-Mount-
>> Shoplight-1290L/204378710
>> They could also bring you a T5HO aquarium fixture from the US, perhaps with
>> some replacement 6,500 K bulbs. Again, these are long and fragile.
>> Of course, there is no way to tell what will be available in 3-5 years.
>> Leo Martin
>> Zone 9?
>> Phoenix Arizona USA
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Southern Germany
Likely zone 7a

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