Teaching Organic Farming & Gardening

Propagation/Greenhouse Management

Unit 1.3 | Part 1 – 119

Lecture 4: Soil Media, Fertility, & Container

Formats

A. Soil Media and Plant Propagation

1. Role of propagation media

a) Whether purchased or made on farm, soil mixes for propagation and seedling
production are designed to provide an idealized growing environment by:

i. Providing a readily available nutrient supply to support steady, healthy plant growth

ii. Holding/retaining adequate moisture to meet plant needs without the need for
constant watering

iii. Allowing excess water to drain rapidly from the media. This prevents or limits the
presence of fungal pathogens and thus allows for proper aeration in the pore space
to promote healthy root development.

iv. Providing an environment for root anchorage and development

v. Being free of pathogens and weed seeds, which could compromise crop growth

b) Nutrients are primarily supplied in organic soil mixes by:

i. Compost: Source of moderate quantities of NPK, and micronutrients

ii. Soil: Field-based soils can provide NPK and micronutrients in small quantities

iii. Organically derived amendments and byproducts: Such as blood meal (13-0-0),
bone meal (4-14-0), cottonseed meal (5-2-1), feathermeal (12-0-0), fish meal (9-3-0),
soybean meal (7-2-1)

iv. Mineral amendments: Such as dolomite (Ca, Mg), greensand (K), rock dusts (Ca, Mg,
micronutrients), sulphate of potash (K, S), soft rock phosphate (P, Ca, micronutrients)

c) Moisture retention in soil media is achieved through the use of:

i. Composts

ii. Peat moss

iii. Coco Peat/Coir Fiber

iv. Vermiculite

v. Leaf mold

vi. To a lesser extent, moisture retention also provided by soil, sand, perlite

d) Adequate drainage in soil mixes is primarily provided by:

i. Coarse sand

ii. Perlite

iii. To a lesser extent, drainage is also provided by compost, vermiculite, peat moss, coco
peat, leaf mold (partially decomposed leaf litter), and partially decomposed wood
byproducts

e) Growing media must also provide aeration, allowing soil pore spaces to exchange O 2
and CO 2. This is accomplished through the use of:

i. Perlite

ii. Sand

iii. Vermiculite

iv. Leaf mold

v. To a lesser extent by peat, coir fiber, and coarse composts

f) Soil media should be pathogen-free and by the nature of its composition and careful
cultural practices, should not be conducive to the development of pathogens

Lecture 4: Soil Media, Fertility, & Container Formats