Agriculture Reference
In-Depth Information
Whatever is used as a seed-starting medium should be light
and easy for delicate roots to penetrate, and it should hold
water well and not be infected with diseases. It should have
some nutrients but not too heavy a concentration of them.
Commercial seed-starting mixes are sold for this purpose and
work fine, as do peat pellets of various shapes and sizes. At
the time of writing, commercial seed-starting mixes cost
about $3 for enough to start 150 plants, and peat pellets cost
about $5 per 100.
Compared to the cost of buying transplants from a garden
center, the price of seed-starting mixes or peat pellets is
negligible. But for a farmer growing hundreds or even
thousands of transplants, it may be economical to make
seed-starting mixes at home. Most seed-starting mixes consist
mainly of finely milled peat moss and vermiculite. The
Territorial Seed Company recommends a simple 50/50 mix of
vermiculite and peat moss, 31 but some authorities
recommend adding compost to the mix because it can
suppress diseases. 32 Some farmers also add a little clean
sand. If these latter two ingredients are added, they shouldn't
constitute more than 1/3 of the soil volume in aggregate.
Don't use garden soil, and don't use potting soil. It is
extremely important that any compost used to make
seed-starting mix be well finished so that it contains no
disease organisms or weed seeds. (Garden soil can be used as
an ingredient if it is first sifted through a 1/4-inch mesh
screen and then sterilized. Instructions for sterilizing are
given later in this chapter. Potting soil can be used under the
same conditions—if it is sifted then sterilized.)
A little compost or worm castings mixed into seed-starting
mixes is fine and can be helpful in warding off diseases. But
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