David R. Hershey dh321 at PGSTUMAIL.PG.CC.MD.US
Fri Apr 11 22:55:34 EST 1997

Two useful features to include in a teaching greenhouse are an intermittent 
mist bench and a photoperiod bench. The mist bench is used for rooting of
cuttings and seed germination. It requires a solenoid valve, mist nozzles,
and some sort of time clock to control the mist interval, e.g. 5 sec. on
every 10 minutes. A rootzone heating pad is also nice for this area. The
area may only be be 10 square feet but it might be larger if you want to
do propagation experiments. Students often find propagation very enjoyable
because they can propagate plants and take them home. A useful text is
Plant Propagtion by Hartmann and Kester (Prentice-Hall). For equipment see
a greenhouse supply catalog such as Hummert (1-800-325-3055). 

The photoperiod bench has incandescent light bulbs suspended above it
about 5 feet apart and a frame made of metal electrical conduit on which
to drape blackcloth and support the bulbs. A timeclock(s) is used to
control the blubs, which in combination with pulling the blackcloth can
give a variety of treatments. At a minimum you probably want at least two
compartments so you can have total dark and a light break in the middle of
the night. In addition to photoperiod experiments, the bench can be used 
to flower plants out-of-season.

Students always seem fascinated by hydroponics, which I have described in 
a series of articles and in my book, Plant Biology Science Projects (Wiley).
A variety of experiments are possible. In addition to the classic 
nutrient deficiency experiments, you can study solution pH changes, 
solution aeration effects, compare hydroponic solutions, compare 
different types of hydroponic systems, etc. 

You have to decide if you want a large collection of permanent plants,
which need to be cared for on weekends, holidays, and during the summer. 
Organizing a student greenhouse club might help solve this problem. 
Related to this is the matter of pest control. Plant collections can
become a haven for pests and require spraying, which usually requires
someone with pesticide applicator certification. Having a period when the
greenhouse is completely empty, as in summer, also helps to keep down
pests. There should be some kind of a quarantine program where plants are
carefully inspected before being allowed in the greenhouse. People will
often want to overwinter their personal plants in the greenhouse and
expect you to take care of them. Have firm rules about this and maintain 
tight security on supplies, like potting soil and tools, otherwise people 
will "borrow" them.

David R. Hershey

Snail mail: 6700 Belcrest Road #112, Hyattsville, MD 20782-1340

Adjunct Professor, Biology/Horticulture Dept.
Prince George's Community College, Largo, MD 20772-2199

Email: dh321 at pgstumail.pg.cc.md.us


On 10 Apr 1997, ARhymer wrote:

> Hello,
> I am a high school biology teacher and I am starting a new botany class for
> upper-classmen this year.  We have a large greenhouse and outdoor garden
> space.  I am in zone 7.  I would be interested in any and all suggestions
> for texts/projects/plants that I could use for this class.  Also, the
> greenhouse will be used by our 500 freshman biology students. It will be a
> great opportunity for them to gain firsthand knowledge.
> I will check the posts here, or I can be reached at
> arhymer at memphisonline.com
> Thank you, Amanda J. Rhymer

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