h.s.botany (misters)

David R. Hershey dh321 at PGSTUMAIL.PG.CC.MD.US
Wed Apr 16 00:50:33 EST 1997

The "Mist-a-matic" can certainly work and is especially useful in areas
where weather conditions fluctuate widely. Timers are most popular because
of their reliability and flexibility. It is very useful to reduce the mist
frequency gradually to "harden-off" rooted cuttings or seedlings before
removing them completely from the mist.  Multiple timers and solenoid
valves also allow several misting frequencies to be employed in different
zones of a bench. Because potting media are well-drained, it is hard to 

Another interesting rooting experiment is to compare rooting in sphagnum
peat moss either plain (pH about 4), with calcium carbonate to raise the
pH to about 7 (about 7 grams per 4-inch potful) or with the same amount of
calcium supplied by calcium sulfate (pH about 4). Is it the pH or calcium
that affects rooting the most? Mum cuttings treated with a rooting hormone
work well in that experiment too. An advantage of sphagnum peat moss is
that its pH can be measured by saturating a sample and gently inserting a
pH electrode directly in the saturated peat. 

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 14 Apr 1997, David W. Kramer wrote:

> >On 10 Apr 1997, ARhymer wrote (in part):
> >> 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.
> David Hershey suggested many interesting activities for the greenhouse and,
> with his usual care and concern, even suggested special pieces of
> apparatus: (just part of his reply)
> ...............>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.  ..............................
> We have a mist bench in our greenhouse which gets a lot of use.  For
> example, we do a simple experiment with chrysanthemums in which each
> student makes two cuttings, treating one with the commercially available
> Rootone (contains an auxin hormone) and leaving the other untreated.  These
> are put in separate containers of moist rooting medium (1 part Pro-Mix : 1
> part sand) and kept on the misting bench for 3-4 weeks.  We then carefully
> remove the soil from each and determine which one forms the most new roots.
> [Note:  This works better with certain varieties of mums than with others
> depending on the amount of auxin that is naturally produced by the
> particular variety of mum that is used.]  It's very important not to let
> these cuttings dry out because initially they don't have roots.
> The main point of my message, however, is that we have switched to a
> different kind of mister than the timer-controlled one Hershey mentions.
> Instead of controlling the mister with a timer we now use a
> moisture-sensing switch called "Mist-A-Matic," also available from Hummert.
> This is better because timers may not water often enough on a sunny
> afternoon and too often on a cloudy day.  The Mist-A-Matic has a stainless
> steel screen on a lever which rises when dry, turning on the mister.  As
> the screen fills with water it gets heavier, moves downward and shuts off
> the water.  Thus watering occurs when (and only when) the cuttings (screen)
> begin to dry... a function of the conditions in the greenhouse.  Catalog
> price is $169.
> Dr. David W. Kramer
> Department of Plant Biology
> Ohio State University at Mansfield
> 1680 University Drive
> Mansfield, OH  44906-1547
> (419) 755-4344  FAX:  (419) 755-4367
> e-mail:  kramer.8 at osu.edu

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