Bedding plants are one of the primary products of the floriculture industry. In the United States, the wholesale value for bedding and garden plants in 2007 was ≈$6.5 billion, which was 58% of total gross sales for floriculture crops [U.S. Department of Agriculture (USDA), 2009]. These crops are commonly grown in plastic containers, which present a significant disposal issue for consumers and the horticulture industry (Hall et al., 2009). Producers of bedding plants may encounter disposal issues of these plastic containers, particularly if plant materials are not sold during a season, and consumers and landscapers must also dispose of plastic containers once the plants are removed (Evans and Karcher, 2004). An estimated 1.7 billion pounds of plastic were used in agriculture in 2002 (Levitan and Barros, 2003).
There are numerous types of alternative, biodegradable containers that can be composted or planted directly into the soil, which eliminate the need for plastic containers (Rodda, 2008). The most common non-plastic biodegradable container has been the peat container. Although referred to as “peat” containers, they are typically made from a combination of peat and waste wood pulp or paper. Peat containers were reported to have advantages over plastic containers by reducing transplant shock and transplanting time, air pruning roots, quicker establishment of finished plants, and their ability to biodegrade (Khan et al., 2000). However, peat containers may have significant disadvantages compared with plastic containers; they are more expensive, they have been shown to have lower dry and wet strength than the plastic containers, and algae can grow on their outer walls (Evans et al., 2010; Evans and Karcher, 2004). Additionally, plants grown in peat containers required more water than plants grown in plastic containers (Evans and Karcher, 2004). When transplanting Jiffy® peat pots (Jiffy Products of America, Batavia, IL), it is recommended to remove or bury the rim of the peat pots so that the rim does not act as a wick to dry out the substrate (Grower's Solution, 2010; Relf, 2009). This will also prevent the peat pot from degrading quickly and reduce root growth into the soil.
Recently, many types of biodegradable containers that are “plantable” (containers that can be used for greenhouse production and then planted directly in the landscape) have become available for the production of bedding plants. These include Fertilpots (Fertil International, Boulogne Billancourt, France) or DOT pots (Bethel Organics, Arcadia, FL) that contain no glue or binders and are composed of 80% spruce fibers and 20% peat; coir fiber or coco fiber containers (ITML Horticultural Products, Brantford, ON, Canada), which are manufactured by using high pressure to bond coco peat and latex from rubber trees; CowPots (CowPots Co., Brodheadsville, PA) that are manufactured from composted cow manure; and Strawpots (Ivey Acres, Baiting Hollow, NY), which are made from 80% compressed rice straw, 20% coco fiber, and a binder (Fig. 1).
Compostable containers are another type of biodegradable container and are not designed to be planted directly into the ground. Once they have been used for greenhouse production, they can be discarded into a compost or landfill facility where they will decompose. These containers include rice hull containers (Summit Plastic Co., Tallmadge, OH), which are made from ground rice hulls and a binder to form a solid container; OP47 containers (Summit Plastic Co.) that are bioplastics made up of 100% renewable starch-based product; and paper containers (Western Pulp Products, Corvallis, OR) that are composed of pressed wood pulp and a minimum of 74% recycled paper, with at least 37% post-consumer recycled (on dry weight basis) (Fig. 1).
Growth of marigold (Tagetes erecta), vinca, impatiens, geranium, and tomato (Solanum lycopersicum) in petroleum-based plastic, peat, and feather containers was investigated by Evans and Hensley (2004). Plants grown in plastic containers had the highest amount of growth followed by plants grown in feather containers, and those plants grown in peat containers had the lowest growth and attributed this to the drying of the peat containers at a much faster rate than either the plastic or feather containers. This was due to the hydrophobic properties of the plastic and feather containers. The mild water stress imposed by the higher rate of water loss may have been instrumental in the reduced plant shoot dry weight in the two biodegradable containers.
Growth of tomato seedlings in biodegradable containers composed of maize, palm, or plastic (control) was investigated by Sakurai et al. (2005a). Seedlings grown in biodegradable containers developed shorter shoots and roots, fewer leaves, lower leaf area and showed a lower dry weight compared with the seedlings grown in plastic containers. Results from this study indicated that irrigation frequency and not nutrient absorption ability was responsible for reduced growth of plants grown in the plastic controls compared with those grown in the biodegradable containers.
Biodegradable containers are a sustainable product that might easily adapt to floriculture production, reduce the use of plastics, and provide excellent marketing opportunities (Rodda, 2008). Marketing studies indicated that the appeal of biodegradable containers has been limited because of their less-than-satisfying appearance. A consumer acceptance study by Hall et al. (2010) showed that on average, consumers prefer rice hull pots the most followed by straw pots. However, previous studies conducted using biodegradable containers indicate that there are significant effects of these containers on plant growth. Although this research provided significant insight into the feasibility of these containers, a more comprehensive study using a wide variety of biodegradable containers to test the performance in greenhouse production and in the landscape is important to determine the overall value of these containers in horticulture production. Therefore, the objective of this research was to evaluate greenhouse and landscape growth of ‘Score Red’ geranium, ‘Grape Cooler’ vinca, or ‘Dazzler Lilac Splash’ impatiens grown in plastic and various types of biodegradable containers at different geographic locations.
Evans, M.R. & Hensley, D. 2004 Plant growth in plastic, peat and processed poultry feather fiber growing containers HortScience 39 1012 1014
Evans, M.R., Kuehny, J.S. & Taylor, M. 2010 Physical properties of biocontainers for greenhouse crops production HortTechnology 20 549 555
Hall, C.R., Lopez, R.G., Dennis, J.H., Yue, C., Campbell, B.L. & Behe, B.K. 2010 The appeal of biodegradable packaging to floral consumers HortScience 45 583 591
Hall, T.J., Dennis, J.H., Lopez, R.G. & Marshall, M.I. 2009 Factors affecting growers' willingness to adopt sustainable floriculture practices HortScience 44 1346 1351
Khan, A.A., Mahmood, T. & Bano, B. 2000 Development of bio-decomposable (Jiffy) pots for raising and transplanting nursery plants Intl. J. Agr. Biol. 2 380 381
Levitan, L. & Barros, A. 2003 Recycling agricultural plastics in New York State. Environmental Risk Analysis Program Cornell Center for the Environment Ithaca, NY
Relf, D. 2009 Plant propagation from seed. Virginia Tech Ext. Bul. 426 17 June 2010 <http://pubs.ext.vt.edu/426/426-001/426-001.html#L6>.
Sakurai, K., Ogawa, A., Kawashima, C. & Chino, M. 2005a Effects of biodegradable seedling containers on growth and nutrient concentrations of tomato plants: 1. Growth and nutrient concentrations before planting Hort. Res. 4 271 274
Sakurai, K., Ogawa, A., Kawashima, C. & Chino, M. 2005b Effects of biodegradable seedling containers on growth and nutrient concentrations of tomato plants: 2. Growth and nutrient concentrations after transplanting Hort. Res. 4 275 279
Uneo, H., Matsumura, N. & Miyaji, M. 2002a Effects of biodegradable pot on growth and quality of pumpkin seedling. 1. Effects on morphological characteristics of the seedling Bul. Expt. Farm Faculty Agr. Ehime Univ. 24 19 25
Uneo, H., Matsumura, N. & Miyaji, M. 2002b Effects of biodegradable pot on growth and quality of pumpkin seedling. 1. Effects on water content and concentration of carbon and nitrogen in the pot soil Bul. Expt. Farm Faculty Agr. Ehime Univ. 24 27 32
U.S. Department of Agriculture 2009 2007 Census of agriculture: United States: Summary and state data. 1(51) 3 Apr. 2010 <http://www.agcensus.usda.gov/Publications/2007/Full_Report/usv1.pdf>.