Starting this growing season the University of Missouri College of Agriculture, Food and Natural Resources’ teaching greenhouses and in-house florist shop, Tiger Garden, will use 100 percent biodegradable pots to grow tomatoes, peppers, eggplants, cucumbers, melons and herbs.
The pots, which resemble coarse cardboard, will replace plastic pots that might otherwise go to the landfill. The biodegradable pots are planted in the ground with the sprouts still in them.
Roots grow through the pot walls and into the soil. The pots eventually dissolve into fertilizer.
Green efforts hit the bottom line, too, as the use of the plantable pots mean less labor for gardeners, said Mary Ann Gowdy, assistant professor of plant sciences at CAFNR. “Sustainable means it has to be economically viable, too.”
No pots in the landfill
The environmental impact is not inconsequential, said Michelle Brooks, greenhouse coordinator. Several thousand of pots are used in the seven CAFNR greenhouses during the year. The closest official recycling center for plastic pots is in St. Louis.
The commercially available, biodegradable pots are generally made of wood fiber and peat moss. Formulas vary; one company’s product line is mostly wood fiber, while another’s is constructed almost entirely of compressed Sphagnum peat moss. No other chemicals are used in the process, save for a little lime used to stabilize the PH of the peat moss.
One line of new pots that CAFNR uses comes from a new company. Another vendor used at the greenhouses has been making such pots in France since 1953. In the classroom, Gowdy and Brooks refer to the biodegradable pots as “living pots.”
Decomposition of the pots depends on the amount of fertilizer applied and on the organic composition of the soil, according to Gowdy. The pots almost completely disintegrate during the growing season because peat moss and wood fiber succumbs to time and microbial activity.
Less labor and healthier roots
While the organic pots are a little more expensive than their plastic cousins, labor savings and plant productivity make up for the few extra pennies per pot, said Gowdy.
Commercial landscapers can expect a 20 percent savings in labor—an important consideration where thousands of plants are used. There is less transplant shock and root disturbances when biodegradable pots are planted into the ground.
As the organic pots retain water in the pot wall, less water is needed for growth. Water and fertilizer distribution to the plant is also more uniform.
The plants have other reasons to be happier, Brooks said. As the root tips easily penetrate the organic walls during their early growth, they are immediately ready to branch out into the soil bed and begin taking in water and nutrients. Plastic pots, Brooks noted, cause the roots to encircle themselves, delaying their spread outward after planting.
Unlike a plastic container, the porous organic pots let oxygen pass through to the roots, helping them quickly branch out.
The one drawback to organic pots is that they are more fragile than plastic containers that can withstand a fall from a workbench or rough handling, Brooks said.
“It is important for us to use these pots because we are interested in our environment and teaching our students sustainable practices,” Gowdy said. “This is an up-and-coming trend. Our graduates need to know about future production practices, not just what was done in the past.”