Propagation/Greenhouse Management
Part 1 – 122 | Unit 1.3
- Beneficial fungal inoculation
Products such as Rootshield can provide growers with a buffer against fungal pathogens in
soil media
a) Trichoderma fungi, when introduced into soil media, can occupy the physical niche that
might otherwise be occupied by pathogenic fungi that can harm seeds and seedlings
b) Trichoderma fungi can also act as direct antagonists to pathogenic fungi, functioning on
your behalf to keep crops healthy
c) Like other living organisms, fungal inoculants should be protected against degradation
and stored refrigerated to extend their shelf life
d) While human health concerns are limited, basic safety precautions like wearing gloves,
long sleeves, a dust mask and eye protection are all recommended when handling
beneficial fungi, as with all other dry, powdered ingredients
C. Environmental Impacts and Sustainability in Soil Mixes and Media
- As noted above, many of the most commonly used ingredients in soil mixes come either
from non-renewable or questionably sustainable sources. Selecting soil mixes for container
grown plants is one of the decisions where organic growers often make choices that may
not be fully in alignment with their philosophical principles.
a) Sustainably oriented growers should seek out non-toxic, naturally occurring, non-
extractive, and renewable resources and byproducts of other processes as a starting
point when trying to build soil mix recipes. When less sustainable choices are made, it is
important to use these costly resources wisely in an effort to maximize their efficacy and
reduce your overall environmental impacts.
b) Live, biologically active mixes are principally reliant on diverse soil organisms, in
the presence of water, for pest and disease suppression, for the decomposition of
undigested organic matter in mixes, and for the release of nutrients from the plant and
mineral derived components of the growing media
c) The grower can control the structure and texture of soil mixes, which dictate drainage,
aeration, and moisture retention, when creating or selecting soil media
d) The structure and texture of your growing media, combined with your cultural
practices—frequency of water delivery, temperature regulation, and the management
of air circulation—should work synergistically to foster healthy, steady, and
uninterrupted growth of seedlings as they move toward transplant maturity
- Storage and handling of soil ingredients and mixes
To maintain the integrity and quality of ingredients and mixes, growers need to take some
basic precautions
a) Protect ingredients from degradation by sun, wind, rain, and extreme temperatures
b) Store ingredients in a cool, well-aerated, rain-free location, away from potential sources
of pathogens and weed seeds infestation. Protecting against these possibilities will go a
long way toward improving crop health, minimizing losses, and reducing labor inputs.
c) Blend mix media in small batches for near-term use:
i. Small batch production is particularly important to maximize the benefits of live,
biologically active ingredients such as the bacteria and fungi present in composts,
and purchased inoculants, e.g., Trichoderma fungi
ii. Long-term storage of large volumes of mix can lead to compaction, loss of structural
properties, and diminished nutrient supply due to volatilization or leaching
iii. If allowed to dry, large volumes of soil can be much more difficult to evenly re-wet for
use in mixes
Lecture 4: Soil Media, Fertility, & Container Formats