BurlingtonFreePress.com, VT
02-03-07
Shine a light on seed-growing
By Dorothy Pellett
Correspondent
Growing plants under lights can be a stimulating high-tech hobby or simply a
means of starting a few seedlings for spring. No matter what the purpose, a
variety of lights is available to meet the needs of plants and gardeners.
Plant growth depends on both the quality of light and its intensity. Other factors to
consider are whether the lights will be used year-around or for a short period;
where they will be located in your home; and whether the goal is growing
flowering or foliage plants, sowing tomatoes and peppers for transplanting to the
vegetable garden, or creating an experience to share with children.
Since gardeners began starting seeds under their extra shop lights, development
of varied types of fluorescent lighting has broadened the possibilities for keeping
seedlings short and stocky instead of spindly. It has allowed orchids and other
tropical plants with different light requirements to be successfully grown in
offices, kitchens and living rooms.
Sunlight contains the complete light spectrum that plants need, and it's the ideal
source. Here in northern areas we are not likely to be able to provide the 14
hours or more of natural light that seedlings of vegetables and annual flowers
require if they are to be in their best condition for planting outside.
Supplementary light usually comes from fluorescent bulbs, and there are
numerous kinds of these.
Fluorescent light bulbs that appear white, often called "cool," emit light in the blue
end of the spectrum. This is the kind of light that allows plants to grow compactly
and sturdily, just what is wanted for the seedlings. Lights emitting more red
wavelengths -- "warm" lights -- will stimulate flowering. A full-spectrum bulb, most
similar to sunlight, offers balanced light that is suitable for seedlings and house
plants throughout the year.
"Technology has improved the quality of the phosphorescent coating on the
inside of the bulb and enabled a better spectrum for plant growth," said Philip
Brett, retail salesman at Gardener's Supply Co. in Burlington. Red and other
colored particles added to the coating of phosphors also add to the cost because
they are made from more expensive minerals.
Other advances in technology have brought bulbs with smaller diameters and
more intense light. The new T-5 bulb, for example, is only five-eighths inch in
diameter. Diane Fuchs of Gardener's Supply Co.'s research and development
division has conducted comparisons of light intensity. The T-5 uses 54 watts of
electricity, compared with 40 for a standard 1.5-inch or T-12 bulb, "but what you
are getting for the extra 14 watts is about 2.5 times the light," Brett explained.
Another high-intensity bulb, the 1-inch T-8, uses only 32 watts and has a light
output about 20 percent higher than the T-12. Electronic ballasts on the newer
bulbs eliminate humming and buzzing.
Caution -- because ballasts are unique for each type, bulbs should be put only in
the correct fixture.
After you have answered the following questions, you will be ready to decide
whether to purchase a complete set of fixtures, stand and lights or to build your
own stand, either to lower the cost or to blend with your dcor:
Will you use the lights all year, making energy efficiency a factor?
Do you want a plant-growing facility that can be integrated into your living room
with slender space-saving bulbs?
Leonard Perry, University of Vermont Extension professor in the plant and soil
science department, said he is constructing new plant-growing stands at his
home, using T-8 bulbs for seedlings that will be planted in the Burlington
waterfront display gardens. "For low cost and to provide a balanced spectrum, I
am using one cool white and one warm white tube," Perry said.
Fixtures are available that hold four, six or eight of the smaller T-5 bulbs. By
installing some cool and some warm bulbs, the light could be varied using
individual switches for each bulb. Serac, a division of Gardener's Supply, builds
sturdy powder-coated aluminum stands on which T-5 or T-8 fixtures can be
mounted.
For adventurous homeowners, Richard Jauron, Iowa State University
Extension horticulturist, suggested last week by telephone that some people
build their own stand from PVC pipe. The Web site www.pvcpipe.com offers
ideas for projects using the pipe with three-way and four-way connectors, elbows
and corners.
Cheryl Felty, owner of Full Spectrum Innovations in Burlington, recommends
160- or 300-watt wide-spectrum incandescent bulbs instead of fluorescents for
plants like Vanda orchids that require high light or for rejuvenating orchid plants
that are slow to bloom. Traditional incandescent bulbs used for home lighting
emit a narrower range of wavelengths less suitable for plants.
The Aero-Garden is an automated fluorescent lighted system small enough to fit
on a kitchen counter. Roots of herbs or other plants are misted with nutrientenhanced water. What it lacks in practicality could be gained in fun.
Whether it's a single tropical plant, a tabletop tray of herbs or a triple-tiered plant
stand filled with seedlings, the dose of simulated sunlight above them can be just
as invigorating for people as for plants.