© 2000 Streamline Publications
A picture can cause a thousand unfulfilled expectations,
Paul Albright remarked, summing up his position on the matter.
According to Albright, unrealistic
expectations is the reason he hesitates to employ photographs in
advertisements and product information sheets. It is especially
problematic for wildflower seed mixtures such as Insecta-Flora,
Albright's popular and highly effective orchard and vineyard cover
crop.
If we were discussing artificial flowers then it wouldn't be
a problem to put in a dozen of this and a dozen of that. But nature is
full of surprises. Like Forrest Gump's box of chocolates, you never
know what you're going to get.
We are very careful about the types and quantities of seed that go
into a mix, Albright continued, but even plants from the same seed lot
can look entirely different planted in different places or in the same
place at different times. For some people that can be pretty
disappointing.
Infinite Variability
In developing seed mixtureswhether for cover crops,
revegetation, erosion control, landscape color, or any other purposecompatibility
of species is important to consider. For example, we generally won't
use Alyssum in a mix because it tends to dominate, Albright
said.
Beyond simple compatibility, the outcome of a mixed seed planting is
dependent on a variety of factorshereditary (genetic) and
environmentalthat conspire against duplication of results.
Indeed, there is little chance that the same patch of flowers will
look the same two years in a row.
The difference in survival, appearance, and vigor of each wildflower
species begins at or before germination and depends on how each of
these factors affects seeds individually and in concert. The
permutations that impinge on a seeds development multiply
exponentially with each alteration in its environment. And there are
many to consider, among them:
- weather
- soil moisture
- soil temperature
- soil preparation
- insects
- disease pathogens
- birds and other pests
Germination and growth also depend heavily on the amount of time
needed to reach each stage of plant development. Common varieties of
wildflowers germinate, typically, in ten days to three weeks. During
that period moisture and temperature changes will favor some seeds
more than others. Seeds requiring less time to germinate may have
greater success simply because that particular period of vulnerability
is shorter.
Sudden Death
Damping off may effect some preemergent seeds and not others. This
condition can occur during the germination period, killing the seeds,
or later, causing the newly emergent plant to rot and die. Certain
types of fungi are responsible for damping off, but viral and
bacterial diseases also damage or kill.
The effects of damping off tend to vary with temperature. Warm
season plant seeds that need higher temperatures to germinate are
especially susceptible to damping off.
Soil nutrients, particularly nitrogen, can have a dramatic effect on
the types of plants that dominate. In revegetation seed mixtures that
contain annual and perennial grasses, high soil nitrogen favors the
faster growing annuals. The slower growing perennials do better when
nitrogen levels are lower.
Biotic Factors
Competition for seeds and seedlings is reduced, but not eliminated,
by creating a compatible seed mixture. Biotic influences on new
plantings come from other living organismsplants and animals. Many
birds and mammals earn their living eating seeds and plants that have
survived germination.
Perhaps the greatest biotic threat is from weeds that suck up soil
moisture and nutrients and crowd out young plants.
Other Environmental Factors
The soil, itself, to support new and sustained growth must contain
adequate nutrientsboth the major elements and the
micronutrients, or trace elements. (See Soil
Health, LEAF-let, May/June 99.)
The proper moisture level in the soil for germination is affected
not only by irrigation or rainfall, but by local humidity and wind,
which draws moisture from top layers of soil.
The soil must be loose enough to allow oxygen to reach roots while
still remaining in good contact with seeds.
Plants which function on photosynthesis need light in the right
intensity and duration. The color of light is important as well, with
the red and blue ends of the spectrum being best.
Its a Hard-Knock Life
No pictures please, Paul Albright says with a grin. Unlike
celebrities escaping the paparazzi, he's only thinking of his seeds.
They have a tough enough time of it without being compared to some
photographic ideal.
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