Controlling Aggressive Annuals
in Combination Planters
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
Click image to enlarge
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
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.