Bagged Soil Tested as an Alternative for Growing Bedding Plants in the Landscape

Abstract

Many homeowners have difficulty establishing ornamental gardens in shallow, rocky soils. “Gardening in a Bag” (planting directly into bags of topsoil) offers a viable alternative for growing many herbaceous ornamental plants. This study compares the growth and appearance of several herbaceous bedding plants using “Gardening in a Bag” versus “in the ground” planting methods. Twenty-five cultivars of Alternanthera dentata R. Br., ornamental pepper (Capsicum annuum var. annuum L.), dianthus (Dianthus barbatus L.), gazania [Gazania rigens (L.) Gaertn.], marigold (Tagetes patula L.), petunia (Petunia hybrida hort. ex E. Vilm.), salvia (Salvia splendens Sellow ex Schult.), peek-a-boo plant (Spilanthes oleracea L.), verbena (Verbena hybrida hort. ex Groenl. & Rümpler), and vinca [Catharanthus roseus (L.) G. Don] were evaluated in 2002 under the two planting methods: in the ground versus in bags of topsoil. Wave petunias, dianthus, vinca, and rose moss (Portulaca grandiflora Hook.) were evaluated using the same methods in 2003. All plants were mulched with 7.5 cm coarse sawdust. In 2002, the planting method had no effect on the average height for 16 of the 25 cultivars tested. Seven cultivars were taller when grown in the ground whereas two cultivars were shorter during that treatment. Planting method had no effect on average plant spread of 13 of the cultivars. Plant spread was greater for nine cultivars grown in bags, whereas three cultivars were wider when grown in the ground. Visual ratings of overall appearance were similar for 14 of the cultivars regardless of planting method. In 2003, performance of the five species was evaluated on 3 July, 29 July, and 5 Sept. Planting method did not affect growth and appearance of rose moss or vinca. The two petunia cultivars and the dianthus tended to be taller and wider and had more flowers when grown in the ground compared with growth in bags. Visual quality of the petunias and the dianthus was unaffected by planting method until September when the `Purple Wave' petunias and the dianthus grown in the ground received better ratings than plants grown in bags.