TOFG-all

Propagation/Greenhouse Management

Unit 1.3 | Part 1 – 125

vi. Cell/plug trays are currently all manufactured from non-renewable sources and even
when recyclable, their manufacture, recycling and eventual disposal have high life
environmental footprints (see Appendix 8, Environmental Impacts of Cell/Plug Trays)

2. Traditional wooden flats, though seldom used in contemporary greenhouse and on-
   farm production systems, have many valuable characteristics as well as several inherent
   disadvantages

a) Advantages of wooden flats for propagation

i. By growing plants at a relatively low density, this format provides a very large root
run. This expanded resource base can grow large, vigorous starts resistant to pest and
disease pressure and tolerant of weather variables.

ii. Substantial nutrient supply per plant means that plants have plenty of nutrients to
grow steadily and without interruption

iii. Substantial soil volume per plant also means growers will have to deliver water less
frequently.

iv. The large soil volume and nutrient supply gives growers a long window of
opportunity to transplant while crops are still in their prime, even if soil or weather
conditions delay planting beyond what would normally be acceptable for cell/plug-
grown crops

b) Disadvantages

i. This format consumes large volumes of soil media, thus increasing production costs
for both labor and materials

ii. Lower plant density afforded by typical spacing in wooden flats means that precious
greenhouse space may not be being used to optimum capacity

iii. Flats filled with well-watered mix, especially mixes that use substantial quantities of
compost, sand, or soil can be very heavy, requiring more labor, and increasing the risk
of lower back injuries

iv. Because roots all grow together in the open flats, this format has much greater
potential for root disturbance and transplant shock even with the most delicate
handling, when individual plants and roots are separated from the inevitable
intertwined root mass.

Lecture 4: Soil Media, Fertility, & Container Formats