All in(doors) on citrus production

19-10-2020    17:15   |    Greenhouse Grower

There are pros and cons when it comes to being one of the first in your industry to do something. The con is that there’s no roadmap to follow, or lessons you can learn from someone else. Every step you take will be a risk to some degree, and expect a lot of trial and error.


Budded citrus liners awaiting either shipment or transplanting. Strip Tags supplied by LODA, inc. The older cones and trays are from Steuwe and Sons.

The pro is that if everything works out, you have the chance to set the mark for innovation in your field. You’ll be a true leader and someone that others can point to as a success story. And if you do make a mistake along the way, you can change course with little second guessing.

Such is the case with TreeSource Citrus Nursery in Woodlake, CA, one of the first outdoor citrus growers in the world to shift to controlled-environment citrus tree production. TreeSource General Manager Roger Smith says the move was largely due to the emerging presence of the Asian citrus psyllid (ACP) in California in the early 2010s. ACP is a vector of the devastating disease known as citrus greening, or huanglongbing (HLB). Florida producers are all too familiar with the tree-killing potential of HLB, and when the disease showed signs of spreading from the processing citrus state of Florida to the fresh-market California industry, Smith says the writing was on the wall.


Trees finishing in 50 mesh Stuppy Super screenhouse storage building. Screen supplied by Green-tek. The blue high speed door in background supplied and installed by Allied Dock Products.

Making the Necessary Adjustments

To be fair, Smith says some growers had started this shift already, but they were growing trees in cold frames, which offered some season extension, but weren’t set up for climate control or automation.

“We had been doing container and field growing for about six or seven years in a cold-frame-style system ourselves, modeled like what some Florida growers were doing,” Smith says. “So, we had an idea of what was needed to modernize our approach to citrus culture in a greenhouse.”

But Smith also knew that in the long term, this approach would be too labor-intensive and expensive.

“I was experienced enough to know that we couldn’t keep doing it the way we were doing it,” Smith says. “We had to design as best we could with no one else to guide us.”

One of the first challenges was deciding which substrate to use. After starting out with a peat-perlite mix, the company switched to 100% coconut fiber in 2013.

“Managing crop variability is a challenge, so we wanted something that would help us optimize root health,” Smith says.

Lighting was also a challenge, as there is very little scientific research into lighting recipes for citrus, which makes it difficult to make informed decisions.

Smith says TreeSource is currently using high-pressure sodium (HPS) lighting and diffused glazing materials. The company has done some LED trials, but the plethora of sunlight available in California, along with constant evolution in LED technology, has kept further investment on the back burner.

Perhaps the most important aspect of the shift to indoor production was keeping pests out of the greenhouse. In California, Smith says USDA’s Animal and Plant Health Inspection Service (APHIS) has a systems approach that mandates citrus nurseries conform to regulatory changes to ensure the grower or homeowner does not get an infected tree.

To enter TreeSource’s facilities, visitors must go through a positive pressure, double-door entry system that pushes air out so insects don’t come in. Fans are equipped with a 50-mesh aphid screen over them, so there are no holes anywhere in the building. USDA inspectors visit the nursery every 30 days to assure ACP exclusion is working, and the California Department of Food and Agriculture also inspects and tests budwood trees to assure the stock is free of multiple diseases while also mandating agreement to extensive compliance agreements.

“We have to take these steps not just for pest management, but also for regulatory compliance,” Smith says. “HLB has transformed the citrus nursery business in the U.S. In the past 20 years, there have been a lot of casualties due to this regulatory shift to protect a multi-billion dollar citrus industry.”


CEO Roger Smith, Sales Manager Heidi Cervantes, Production Manager Erick Valle holding a tray of rooted cuttings. Finished trees in background on roller t-rail benches supplied by Stuppy. 120 cell tray of citrus liners sitting on Metazet M-track.

Three Lessons

Smith perhaps best sums up TreeSource’s formative years of moving to indoor production with these three lessons:

“First, we didn’t want to simply create an indoor nursery that was like an outdoor nursery,” Smith says. “We couldn’t use the same pot or the same irrigation system. We had to learn as much as we could about the citrus plant itself, and what its needs were. It was almost like reinventing the growing process.”

The second lesson was that in the field you can’t really manage the variability of the crop, and you have to deal with Mother Nature.

“In the greenhouse, we now had the tools to manage the crop, but we had to learn how to do so in a way that would optimize production and maximize return on investment. Because citrus is inherently variable, we had to move the plants around a lot and cycle the space, and that means efficiency is important. That was the key to our design.”

The final lesson Smith learned was that when new technology comes out, you have to decide whether it’s worth jumping on right away.


Sprouting by hand. Social distancing has made this job more isolated from other workers than in previous years.

“We are open to innovation, but just because we can doesn’t mean we should,” Smith says. “That’s a guardrail that keeps us dialed in to what we need to do.”

How Tech Improved Efficiency

Every decision on the layout of the greenhouse, from rolling benches to moving trees in the greenhouse, was based on plant movement and automation in a way that would best maximize worker efficiency. (Click here see a slideshow highlighting the technology used in TreeSource’s green-house citrus production.)“The roller benches were a big part of our initial design, and we’re continuing to add more,” Smith says. The system works well, and integrates seamlessly with Metazet’sM-track trolley that robotically transports citrus liners and transplanted trees throughout the greenhouse.

“It’s very ergonomically friendly to our workers, and there’s very little lifting involved,” Smith says. “We’ve learned to be careful with new ideas, as any design changes we make have to be done to accommodate the existing system.”

Smith understands that automation systems are expensive, but he says it shouldn’t be about what they cost, but how much they can save.

“We focus on payback, which we have to do as we look to become more efficient due to the rising costs of labor,” Smith says. “Our parent company, AC Foods, funded a 2017 expansion that gave us a 40% increase in capacity, but it wasn’t just the capacity. We needed to find ways to expand, but not add to our workforce.”

Once the technology investment was made, it then become critical for TreeSource’s production team to use it in the best way possible.

“We hired FlowVision in 2019, and our team  did a wonderful job in adjusting, learning, and adapting, and helped us save even more than we expected,” Smith says. “That was the first year we set a company-wide efficiency goal, and they are running even more efficiently in 2020 based on their inertia from last year’s successes.”

Keys to Success

One of the first innovations in TreeSource’s 21-year history was a citrus liner (CL), first developed in 2001. Most citrus trees in the world are T-budded onto a rootstock seedling that has been planted either in the field or in a pot. TreeSource figured out how to do this in a 1-inch by 8-inch cone using a cleft bud technique. This created a whole new citrus product that could be supplied to other nurseries, even internationally. Today, the company has a national presence with their CLs and expects to propagate 1.5 million in 2020, with refrigerated container loads even going to Maui. Customer demand also prompted the recent introduction of rooted cuttings, and the team is considering vertical farming technology to expand this part of the business.

In reaching the goals Smith and the TreeSource team have set out to accomplish these past few years, one thing that has been very helpful is listening to the advice of seasoned experts from similar industries. This even predates the company’s transition to indoor production, when it first met with Proptek, a propagation container and tray company during what was at the time the OFA Short Course.

“We based our original container design, and our whole operation, in fact, on a new container [Proptek] had designed. It was large enough to grow a citrus tree using air pruning technology in a frame that could hold eight pots at a time, which was a huge labor saver,” Smith says.

More recently, Smith has networked with growers from the International Society of Citrus Nurseries to share ideas, while turning to consultants such as FlowVision.

“We’re finding that we don’t always have the time to break down our processes and look for ways to improve like the FlowVision team does,” Smith says. “They made a couple suggestions that have resulted in mind-boggling efficiency changes to what we were doing. It has been great working with them, and well worth the investment to achieve the results.”

Along the way, there have been some mistakes, such as fixing the design of the pots to reduce media drainage, and perhaps making too much of an initial investment on screenhouses rather than greenhouses.

“Citrus really likes to grow inside a greenhouse,” Smith says.

The sooner you can learn from those lessons, the sooner you can try something new. It’s a philosophy that will continue to drive TreeSource Citrus Nursery into the future.

“When you innovate, you find things that work that you may not have thought of,” Smith says.

Click here to check the photo gallery of the citrus greenhouse.

Source and Photo Courtesy of Greenhouse Grower


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