Smaller operations may feel they can do everything a PGR will do by hand with extra labor. However, the labor cost of moving the plants and controlling their growth can add up. Photo: Fine Americas
Many growers are familiar with plant growth regulators (PGRs). Some use them frequently, yet others shy away for various reasons. Often, those reasons aren’t as valid as they may have been years ago. We talked with Dudley Dabbs, Sales Manager, SE at Fine Americas, and Dr. JC Chong, Ornamental Technical Development Manager at SePRO, to find out what they hear around the watercooler and get the facts.
PGRs Cost Too Much Money
Both Dabbs and Chong agree that there’s a common misconception that PGRs are expensive to use. While they aren’t free, growers find overall savings in labor, plant marketability, and even the ability to flex delivery schedules well worth the investment.
“Medium- and large-size growers use a lot of PGRs. They’ve figured out that a PGR doesn’t cost them money. It makes them money. Labor is not only expensive, but good labor is hard to get now more than ever,” Dabbs says. Often, he explains, smaller operations feel they can do everything a PGR will do by hand with extra labor. However, the labor cost of moving the plants every time they stretch, and controlling their growth, can add up.
“A bunch of days of cloudy weather in a row makes those plants want to stretch more than anything. You have to work hard moving plants around so they can have extra space. You don’t have to do that with a PGR,” Dabbs says. “It’ll keep them in check, reduce having to move the plants as much, and control the plant height to keep them from getting out of control.”
“One of the benefits of using a PGR in woody perennial production is saving labor,” Chong says. Instead of pruning plants multiple times over the production cycle, the plant can be pruned to shape and then held with a PGR.
“That’s not just for nursery production but for greenhouse production as well. Save labor expenses and ultimately come out ahead of your budget.”
Delays in shipping, whether related to the weather or vendor needs, can spell problems for a finely tuned and scheduled crop. A buyer asking to hold a shipment can be costly.
Dabbs describes a common scenario: “You get a call from whoever you’re selling to, and they say hold them, don’t ship. What are you going to do now?” He explains that a PGR can stop the plants where they are, temporarily holding them at the right size so they stay sellable.
PGRs Won’t Work on My Plants
“I think PGRs are for everybody,” Chong says. With broad applicability, they work on more than just annuals. Herbaceous and woody perennials can also benefit from PGR use.
“There’s a lot being used in the landscape for established tree and shrub control, and we’re using quite a bit of it in nursery production for woody plants,” Chong says. “It’s an area folks are not really exploring as much as they should.”
“People think if they buy a PGR, there’s a very limited range of what it can be used on. It’s completely untrue. Look at the labels. You’ll find, in fact, a complete and exhaustive list of all the different crops that PGR can be used on. They’re very effective across almost everything we grow in the greenhouse,” Dabbs says.
While a product may be suited for broad use, that doesn’t mean each crop reacts the same, or that there is a uniform application rate across multiple varieties.
“There’s definitely the need to tailor rates for different crop species for sure — the responses are going to be different,” Chong says. For growers with many varieties and sizes, he recommends grouping plants based on similar application timing or dosage to simplify application.
PGRs Will Delay Flowering
A PGR is, at its simplest, messing with the plant’s growth in some way, whether advancing or slowing it. At some point, folks start to worry about delaying flowering, afraid they will end up with a stunted crop that won’t bloom.
“Some people are afraid if they use a PGR, it will delay flowering or maybe reduce the size of the flower,” Dabbs says. Part of that misconception is true. Picking the wrong PGR or application method can result in delayed flowering or other bloom issues.
“There’s quite a bit of fear about that for sure. And I think that’s probably one of the biggest reasons why people don’t want to use PGRs; they’re afraid it might actually damage the crop itself,” Chong says. “It’s absolutely true that some of the PGRs, if misapplied, might actually lock down the flowers.”
Most of the time, Chong says, the problem is overdosing. “Any kind of phytotoxicity is usually associated with using too much PGR, so dialing down the rate using trial and error is pretty important.”
Some PGRs can lock down or delay flowering, but there are products available that won’t, and matching the application method and timing to the crop makes a big difference.
“Paclobutrazol is the most popular PGR in the industry today. Instead of using it as a spray, use it as a drench if you’re concerned about delaying flowering. It’s actually a bit more economical with longer-lasting control, and there’s no chance of having any delay,” Dabbs says.
PGRs Can’t Be Applied in Tandem with Other Products
Growers may assume PGRs need to be used as a separate application to the crop, creating more hassle, but that’s also not the case.
“They don’t need to be used by themselves at all. You can put them out along with fungicides and insecticides,” Dabbs says. “Again, it’s the idea of saving labor. Instead of making multiple trips across the greenhouse, whether it be with a boom or individuals, you can combine them to save time.”
They can also be added to your fertigation tank for drench applications. At first glance, the idea of applying a regulator and fertilizer at the same time seems contrarian. But as Dabbs explains, it can make sense, and some growers do it often.
“We’re trying to keep plants green and healthy, but we’re also trying to keep them in check at the right height,” he says. “You need to keep the plants fed, but you don’t want them to take off. Fertilize, but add a regulator to keep them in check. You can easily tie into what you’re already doing.”
