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College of Agriculture >Plant Growth Center
College of Agriculture &
Montana
Agricultural Experiment Station
Growing Media
There are
three standard growing media available for PGC users. Custom mixing of growing
media is available, please discuss your requirements with the PGC manager.
MSU
Mix
Mineral soil,
Canadian Sphagnum peat moss and washed concrete sand are blended on a 1:1:1
by volume ratio. The wetting agent, Aqua-Gro 2000G is added to the mix at the
rate of one pound per cubic yard. This additive allows for easier initial watering
of the mix. MSU mix is aerated steam pasteurized using the Lindig soil treatment
system for one hour at 70C.
Soil test
results (July, 2004) for MSU mix show a pH of 6.1 and EC of 0.9 dS/m. Test results
will vary as the mineral soil component is purchased from a private vendor and
is often a composite of various soils found in the Gallatin valley.
Sunshine
Mix #1
This commercially
available soil-less mix is a blend of Canadian Sphagnum peat moss and horticultural
grade Perlite. Sunshine Mix #1 is buffered with Dolomitic lime and contains
a starter fertilizer charge and wetting agent. Test results (July, 2004) show
a pH of 5.9 and EC of 1.1 dS/m.
50:50
Mix
50:50 Mix
comprises of half MSU Mix and half Sunshine #1 by volume. This mix is offered
for users desiring a mix with a lower bulk density than MSU mix, but retaining
a mineral soil component. 50:50 mix doesn't shrink in the container when dry
as much as straight Sunshine Mix #1.
Media
Selection Guidelines
Your selection
of a growing media largely depends on container size and the desirability of
a mineral soil component in the media. Sunshine Mix #1 is the best choice when
growing in shallow flats, plug trays, small pots (6” and smaller) and 1020 flat
inserts (i.e. six packs). Your plants will benefit from the greater porosity
of the Sunshine Mix #1 in these styles of containers.
Use MSU
Mix when a mineral soil component is desired. MSU mix performs best in 6” and
larger pots. Over time MSU Mix's pH will rise over time more so than Sunshine
Mix. If your plants require slightly acidic media conditions, and you are growing
in MSU mix, you will need to pay close attention to pour-through test results
and make the appropriate fertilizer selection to maintain desired media pH levels.
Details on the pour through test and fertilizer selection are covered in the
Water Quality and Fertilization
section.
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