PGR advantages

Plant growth regulators provide cost savings and production efficiencies for both greenhouse and nursery growers. PGRs can reduce water and nutrient requirements, decrease labor and reduce plant spacing. PGRs also help produce a more consistent crop, which increases sell-through.

Ornamental growers are under increasing pressure to deliver plants with optimum size, shape and quality at competitive prices. To help achieve such an important objective, several PGRs are available to growers.
Many large growers apply PGRs to bring a higher level of precision to their production programs, said Kevin Forney, technical services manager at Fine Americas, Inc.

“We have some customers who use growth charts to accurately predict plant height throughout the growing cycle based on their PGR applications,” he said.

Incorporating PGRs is a common practice at Catoctin Mountain Growers in Detour, Md., said Julie Iferd, head grower.

“It’s hard to imagine growing without PGRs,” she said. “Not everything gets a PGR application, but it’s an important part of our production plan. It saves bench space and allows for tighter spacing.”

PGRs can reduce plant spacing in the greenhouse by as much 20 percent according to Brian Whipker, professor of floriculture at North Carolina State University. This allows more plants per square foot and lower overall fixed production costs.

“The benefit of lower fixed costs alone can deliver a 10X payback on a grower’s PGR investment,” Whipker said.
And Whipker’s research reveals more benefits beyond spacing and shipping. With PGRs, growers can cut their water and fertilizer use by up to 20 percent, he said.

From cart to store
Low-dose applications of certain PGRs provide economical means of limiting growth once a crop has reached a desired height, according to Whipker.

“Growers can get their plants up to a specified height, then use low doses of PGRs to maintain them at that height until they’re ready to ship,” Whipker said.

And tall plants are typically harder to sell and harder to ship, said Larry Morgan of South Central Growers in Springfield, Tenn.

“By reducing the size of the plant, the consumer gets a better looking plant to enjoy, and growers are able to ship more plants on carts,” Morgan said.

Besides shipping more pots on a cart, plants experience less damage during shipping, said Brad Hawcroft of Layman Wholesale Nurseries in Johnston, S.C.

Education, experimentation
Because retailers and consumers have high expectations for plant habit, it’s important for growers to use PGRs on many varieties to control the height and architecture of their plants, Whipker said.

Retailers don’t want noticeable variations in size, shape and color in the plants they receive, Forney said.

“Consumers tend to pick through displays and leave less desirable plants behind. In many cases, those plants never make it out of the store and often end up in a dumpster as shrinkage,” Forney added.

Read labels, ask fellow growers and trial PGRs on plants for best results. Applying PGRs is not like baking a cake, Morgan said.

“You can’t always go by a recipe. The grower decides by experience. We’ve learned that most plants respond well to PGRs, while landscape grass is hard to control and begonias are very sensitive to anything,” he said.

Iferd has learned that PGRs are fantastic on Wave petunias, but care must be taken when applying them to New Guinea impatiens. Layman Wholesale Nurseries applies PGRs to both annuals and perennials. There was a bit of a learning curve regarding applications on perennials.

“It was a two- to three-year learning curve with perennials vs. annuals because there are fewer crop cycles for experimentation, but both annuals and perennials require research and testing,” Hawcroft said.

He’s found that dianthus, Alcea, delphinium, rudbeckia and digitalis are some of the crops that respond well to PGRs, while crops like clematis, fern, Thymus and Saxifraga don’t need them.

PGRs can help growers achieve higher levels of customer satisfaction and improved profits. “PGRs don’t cost money, they make you money,” Whipker said.