Reduce Flowering Time

Fig. 1. Nemesia ‘Aromatica Royal’ and Osteospermum ‘Voltage Yellow’ finished in a common greenhouse with a daily light integral of approximately 12 mol•m¯²•d¯¹  from cuttings propagated under 2.0 to 12.3 mol•m¯²•d¯¹  during rooting. The photo is taken two weeks after transplanting.

This is the second article in a two-part series looking at the effects of light during cutting propagation. While the first article focused on the effects of daily light integral (DLI) during propagation of rooted cuttings, this article will focus on finished plants. We wanted to see how DLI during propagation affected growth and flowering after transplant, as well as identify how the DLI during propagation interacted with the DLI during finishing to influence crop timing and quality.

Study 1: Lighting During Propagation

Cuttings of Angelonia ‘AngelFace White,’ Nemesia ‘Aromatica Royal,’ Osteospermum ‘Voltage Yellow,’ and Verbena ‘Aztec Violet’ were stuck in 105-cell trays and placed in a propagation greenhouse with an air and substrate temperature set point of 73°F and the average DLI was maintained at about 5 mol•m¯²•d¯¹. After seven days, cuttings were placed under a range of DLIs, from 1.2 to 12.3 mol•m¯²•d¯¹, achieved using supplemental light from high-pressure sodium (HPS) lamps and no shade or shade cloth providing 31 percent, 68 percent or 86 percent shade.
In order to identify any residual effects of propagation DLI on subsequent growth and development during finishing, cuttings from the various propagation DLI treatments were transplanted and grown in a common environment.

Two weeks after cuttings were placed under the propagation DLI treatments, cuttings were transplanted into 4.5-inch containers filled with a commercial soilless substrate. Plants were grown in a greenhouse with an air temperature set point of 70ºF and an average DLI of about 12 mol•m¯²•d¯¹ and fertilized with 200 ppm N from a balanced fertilizer at each watering. When the first flower opened on a plant, we collected data including time to flower from transplant, flower bud and branch number, plant height and shoot dry weight.

Study 2: Lighting During Propagation And Finish

In a separate study, cuttings of Angelonia ‘AngelMist White Cloud,’ Nemesia ‘Aromatica Royal,’ Osteospermum ‘Voltage Yellow,’ and Verbena ‘Aztec Violet’ were stuck in 105-cell trays and placed in a propagation greenhouse with an air and substrate temperature set point of 73°F and the average DLI was maintained at about 5 mol•m¯²•d¯¹.  After seven days of callusing, cuttings of each species were placed under one of three propagation DLIs, achieved as previously described using different shade cloths and supplemental lighting.

After two weeks under the DLI treatments, cuttings from each propagation DLI were transplanted and placed in a greenhouse under one of three DLI treatments for finishing. The different finishing DLIs were achieved similar to those in the propagation environment — with the use of no shade cloth or varying levels of shade cloth and supplemental light from high-pressure sodium (HPS) lamps. This resulted in nine unique combinations of propagation and finishing DLI treatments. As with the cuttings study, when the first flower opened on a plant, we collected data including time to flower from transplant, flower bud and branch number, plant height and shoot dry weight.

Summary Of Results:Lighting During Propagation Study

The number of days from transplant to flowering decreased as propagation DLI increased for all four species in this study (Fig. 1). For example, time to flower was reduced by 23 and 19 days for angelonia and osteospermum, respectively, as DLI during propagation increased from 1.2 to 12.3 mol•m¯²•d¯¹. Neither the number of nodes below the first open flower nor flower buds for angelonia, nemesia and verbena were influenced by propagation, indicating that flowers had initiated before propagation began. With the development of cultivars that are less photoperiodic, controlling the flowering of free-flowering cultivars is a new challenge growers are facing.

The DLI during propagation also affected shoot growth, plant height or stem length, and the number of branches at flowering. Shoot dry weight of all species decreased as propagation DLI increased. Similarly, the number of branches for several species decreased with higher DLIs during propagation. As DLI during propagation increased from 1.2 to 12.3 mol•m¯²•d¯¹, plant height of angelonia and osteospermum at flowering decreased by 2.5 and 1.5 inches, respectively, while stem length of verbena was an exception to this trend and was unaffected by DLI. For cuttings propagated under higher DLIs, the reduction in shoot dry weight and branching at flowering may be related to the faster flowering. When plants flower more quickly, there is less time to “bulk up” shoot growth and allow branches to develop.

Summary of Results: Lighting During Propagation And Finish Study

Similar to our first study, the time to flowering for all species decreased as propagation and finishing DLIs increased (Figs. 2 and 3). For example, as propagation DLI increased from 1.5 to 16.8 mol•m¯²•d¯¹ and finishing DLI increased from 4.6 to 17.5 mol•m¯²•d¯¹, the time to flower after transplant for angelonia, nemesia, osteospermum and verbena decreased by 26, 46, 25 and 26 days, respectively. Similarly, both propagation and finishing DLIs influenced flower bud number. The number of flower buds of angelonia, nemesia, osteospermum and verbena increased as both propagation and finishing DLI increased. Generally, though DLIs during both stages influenced the time to flowering and flower bud number, propagation DLI appeared to have a greater influence on time to flower while the finishing DLI had a greater influence on flower bud number.

The DLI during propagation also interacted with finishing DLI to affect the growth of angelonia, nemesia, osteospermum and verbena. While shoot dry mass at flowering for species decreased with propagation DLI, shoot mass increased with finishing DLI. However, the finishing DLI resulted in a greater increase in shoot mass for cuttings propagated under lower DLIs compared to cuttings propagated under higher DLIs. Again, this relationship between shoot mass and propagation and finishing DLIs is most likely related to the time to flower.

Height was influenced differently by propagation and finishing DLI among species. For example, the height of nemesia decreased by nearly 60 percent as both propagation and finishing DLIs increased from 2.0 to 16.8 mol•m¯²•d¯¹ and 2.0 to 17.5 mol•m¯²•d¯¹, respectively. Alternatively, height of angelonia and osteospermum were relatively unaffected by propagation and finishing DLI.

The influence of propagation DLI and finish DLI on branch number varied among species. For example, angelonia propagated and finished under low DLIs averaged no branches, while plants propagated and finished under higher DLIs had 4 branches. While both propagation and finishing DLI influenced branch number, the DLI during finishing had a stronger impact.

Economics Of Supplemental Lighting

Lighting during propagation may save you money by reducing the finishing time for plants and, as in our previous article, we will use Virtual Grower to demonstrate this. Angelonia cuttings propagated under 5 mol•m¯²•d¯¹ will finish in 32 days, while angelonia propagated under 10 mol•m¯²•d¯¹ will finish nine days earlier. The energy costs during finishing for angelonia  in a 1-acre glass-glazed greenhouse with a 70°F air temperature in Indianapolis, Ind., in March would be $0.58/ft² and $0.42/ft² for cuttings propagated under 5 and 10 mol•m¯²•d¯¹, respectively. Therefore, lighting during propagation could potentially reduce finishing energy costs by 27 percent.

In addition to potential energy savings, let’s take a look at the efficiency of lighting during propagation versus finishing. For a 105-cell tray, there are about 76 cuttings per ft², whereas a square foot of 4-inch pots may have from four plants per ft² (spaced on 6-inch centers) to nine plants per ft² (spaced pot-to-pot). Therefore, a square foot of illuminated bench space in propagation can have from 844 to 1,900 percent more plants under light compared to during finishing! Furthermore, propagation areas are generally a fraction of the total production area for growers who propagate in-house, meaning a lower initial investment to light your propagation area.

The Take-Home Message

Our studies show that DLI during propagation and finishing of bedding plants clearly impacts the growth, timing and quality of finished annuals. However, our studies also demonstrate that DLI during propagation and finishing affect finished plants differently. For example, propagation DLI appears to have a stronger effect on the time to flower, while finishing DLI has a stronger effect on flower bud number and shoot dry weight.

When the energy savings during finishing and of lighting propagation space are taken together, using supplemental light may be considered a “low-hanging fruit” when looking at ways to reduce crop time and increase finished plant quality. Growers will need to evaluate their goals and priorities when making management decisions related to investing in supplemental lighting.

Leave a Reply

More From Structures & Equipment...
Four Star Greenhouse Proven Winner Plants At English Garden

May 26, 2015

Retailer To Grower: It’s Time To Offer Services To Local Garden Centers, Too

Retailers wonder why mass merchants are the only ones to receive stocking, merchandising and plant care from growers.

Read More
Greenhouse Electrical System

May 26, 2015

Don’t Let Your Greenhouse Electrical System Come Up Short – Part 1

Ensuring your greenhouse has enough electricity to operate all the equipment that is installed takes planning and consideration of an operation's needs. Part one of two articles on greenhouse electrical systems covers choosing an electrician, meeting immediate and future needs and planning for back-up power.

Read More

May 22, 2015

Nexus Greenhouses Is Optimistic For Expansion Into New Markets

Cheryl Longtin and Mike Porter, who own Nexus Corporation, say they were excited to attend the grand opening of Gotham Greens’ new structure atop the new Whole Foods grocery store in the Gowanus neighborhood in Brooklyn, N.Y., when it opened in December 2013. The project is just one example of some of the new and expanding markets that Nexus Corporation has expanded into over the past few years. Jeff Warschauer, vice president of sales for Nexus, says the company has enjoyed getting to know and working with the founders of Gotham Greens, Viraj Puri and Eric Haley, and Jennifer Nelkin Frymark, the chief agriculture officer, on their innovative approach to business. “They are very excited and work hard internally – just great people,” he says. “From our perspective, it’s great to see that excitement and vision. The employees there are happy and there’s no turnover; they’re only adding new people […]

Read More
Latest Stories
Greenhouse Electrical System

May 26, 2015

Don’t Let Your Greenhouse Electrical System Come …

Ensuring your greenhouse has enough electricity to operate all the equipment that is installed takes planning and consideration of an operation's needs. Part one of two articles on greenhouse electrical systems covers choosing an electrician, meeting immediate and future needs and planning for back-up power.

Read More

May 22, 2015

Nexus Greenhouses Is Optimistic For Expansion Into New …

Cheryl Longtin and Mike Porter, who own Nexus Corporation, say they were excited to attend the grand opening of Gotham Greens’ new structure atop the new Whole Foods grocery store in the Gowanus neighborhood in Brooklyn, N.Y., when it opened in December 2013. The project is just one example of some of the new and expanding markets that Nexus Corporation has expanded into over the past few years. Jeff Warschauer, vice president of sales for Nexus, says the company has enjoyed getting to know and working with the founders of Gotham Greens, Viraj Puri and Eric Haley, and Jennifer Nelkin Frymark, the chief agriculture officer, on their innovative approach to business. “They are very excited and work hard internally – just great people,” he says. “From our perspective, it’s great to see that excitement and vision. The employees there are happy and there’s no turnover; they’re only adding new people […]

Read More
Canadian Army Reserve training at GGS Structures.

April 30, 2015

GGS Structures Hosts Canadian Army Reserve Tactical Tra…

GGS Structures showed support for the Canadian military by opening up its fabric-covered Tasco Dome for tactical training to help soldiers prepare to fight in urban settings.

Read More
Growers are looking for low-cost options for temperature control, like circulating fans and exhaust fans.

April 10, 2015

New Ways To Give Growers Control Of The Greenhouse Envi…

From heating systems to circulation fans, manufacturing companies are finding new ways to help growers control the greenhouse environment, save on energy costs and streamline production.

Read More
Hendriks-Half-Open-Roof_GGS

March 26, 2015

10 Greenhouse Products For First-Rate Growing Environme…

From coverings to fork-lifts, greenhouse suppliers offer a variety of products to make growing easier. Check out the slideshow to learn more about these, plus several other products that can offer you value, versatility and durability.

Read More

March 16, 2015

Cozy Acres Greenhouses: Operating With Zero Emissions

With the help of federal funding, Cozy Acres Greenhouses was able to take a greener approach to its latest expansion, building a zero emissions greenhouse that operates year round.

Read More
interior view EDDG vent_energy efficiency codes

March 16, 2015

Stricter Energy Codes May Impact Your Ability To Expan…

Energy efficiency building codes that greenhouses are required to meet could soon be much more stringent, unless the National Greenhouse Manufacturers Association is successful in its bid to gain exceptions on greenhouse owners’ behalf.

Read More
NorthCreekGreenhouse_midmarch15

March 13, 2015

GGS Helps North Creek Nurseries Take Efficiency To A Ne…

North Creek Nurseries recently built a new GGS gutter connected poly greenhouse range with the intent of saving energy and implementing Lean Flow Practices. The aim was to help North Creek improve the quality of products and meet increased customer demand, while at the same time saving money on labor.

Read More
Polyarch Berns

March 12, 2015

Energy Audit Resources To Reduce Energy Costs In The Gr…

One way to reduce energy-related costs in the greenhouse is to conduct self-audits on a regular basis. These energy audits allow growers to identify potential savings by checking various production systems. To ensure your operation is running efficiently, check out these resources for help with your energy audit.

Read More
Retail Greenhouse

March 12, 2015

The Right Greenhouse For Any Grower

Selecting the right structure for your operation can be difficult. With so many options, it’s easy to feel overwhelmed. The good news is that greenhouse manufacturers are experienced in the art of matching customers with the ideal product. Here’s their advice for how to pick your next structure.

Read More
Fall Creek Farm and Nursery Expansion

March 12, 2015

Conley’s Helps Fall Creek Farm And Nursery Increase Blu…

In order to meet its customer’s increasing demands for domestic blueberry production in the United States, Fall Creek Farm and Nursery needed much more indoor growing space. The company selected Conley’s for a recent expansion of Conley’s Gable Series 7500 in a two-phase project. The first 14-greenhouse range sold by distributor Horticulture Services, measures 170,000 square feet in size and finished construction in 2013.

Read More
Emerald Coast Grower's Atlas Greenhouse

March 12, 2015

Emerald Coast Growers Steps-Up Production Efficiency An…

Emerald Coast Growers, a supplier of perennial starter plants and ornamental grass liners, is not averse to expansion projects. In 2010, it celebrated its 20th anniversary with an expansion of its perennial production space. More recently, the company has been in a nearly continuous phase of construction and improvement projects.

Read More
ArmstrongGrowers Hanging Basket Area

March 12, 2015

Armstrong Growers And Pike Farms Grow With Sustainable …

Rebuilding and retrofitting greenhouses has been key to Armstrong Growers’ expansion on the West Coast, and Pike Farms will follow the same business model on the East Coast. The four-acre wholesale operation that is currently Pike Farms produces only about 5 percent at the most of Pike Nurseries’ retail garden center needs; however, that’s going to change in the next couple of years.

Read More
Metrolina Greenhouses Loading-Dock

March 12, 2015

Metrolina Greenhouses Expands With High- And Low-Tech …

Heralded as one of the most automated greenhouse operations in the U.S., Metrolina Greenhouses continues to build in Huntersville, N.C., and York, S.C. Art Van Wingerden, chief operating officer and co-owner of Metrolina Greenhouses, estimates that as his big box customers continue to grow at a 3 to 5 percent rate, so will Metrolina Greenhouses’ growing facilities to keep up with demand.

Read More
Polyarch Berns

March 12, 2015

The Energy Efficient Greenhouse

New coverings technology means today’s films, plastics, shade cloths and climate screens slash heating and cooling costs while improving crop productivity year round. We checked with manufacturers to see what’s new and uncovered some best practices for buttoning up your greenhouse. Here’s what you need to know about the latest trends.

Read More
FormFlex_MTZ Hanging Basket

March 11, 2015

4 New Ways To Automate Your Operation

These new automation products can help streamline labor-intensive tasks, saving time and labor and increasing productivity.

Read More
GrowCo_greenhouses

March 10, 2015

Greenhouses Are More Efficient For Marijuana Production

At least 30 percent more efficient and productive than warehouse growing, greenhouses are the way of the future for commercial cannabis production, experts say. Cannabis growers and advisors are starting to move production out of the warehouse and into the greenhouse, to benefit from the efficiencies that the sun’s natural light and environmental controls provide.

Read More
Pleasant View Gardens New Expansion

March 10, 2015

Pleasant View Gardens Transitions Old-School Hoop Hous…

A new production expansion optimizes labor efficiency and adds growing space, while optimizing energy use.

Read More