P&PDL Picture of the Week for
June 21, 2010

Controlling Aggressive Annuals in Combination Planters

Roberto G. Lopez, Ph.D., Assistant Professor & Floriculture Extension Specialist, Purdue University

Liner dips or plug dips are a relatively new PGR (plant growth regulator) application method that is increasingly being used by greenhouse growers.  This application method involves placing a plug tray in a shallow PGR solution, allowing the chemical to absorb into the growing media.  After the chemical application and when plants are safe to handle, the young plants are subsequently transplanted into hanging baskets or combination containers. 

Combo planters often include plant species with different growth habits and development rates and thus conflicting PGR requirements.  Aggressive species such as sweet potato vine can grow too fast and quickly dominate the container, out-growing less vigorous species (Figure 1).   For more information on liner dips and rates, visit our Floriculture Extension page.



Click image to enlarge

Combination hanging planter

Figure 1. Example of a hanging basket planted with an aggressive species (sweet potato vine) and a less aggressive species (calibrachoa). The sweet potato vine is outgrowing the calibrachoa in the container. The sweet potato vine treated with a PGR plug dip before transplant could have suppressed vigor, allowing the calibrachoa to become better established.

Plants comparison

Figure 2. ‘Goldilocks’ lysmachia and ‘Royal Tapestry’ alternanthera plants grown from liners dipped in solutions containing 0, 4, 8, or 16 ppm Concise (uniconazole) for 30 seconds preceding planting.  Photos taken six weeks after treatments were applied.

Purdue Plant & Pest Diagnostic Lab Purdue Cooperative Extension Service