Containerized culinary herbs are popular year-round. But as ubiquitous as they are, they present a key production challenge: controlling their growth.

Unlike fresh-cut culinary herbs grown in hydroponic systems, the size of container-grown herbs is important. First, more compact finished plants can improve space utilization, from closer spacing on the bench to increased plant densities in the greenhouse. Second, more compact herbs can improve water and nutrient use, as less is consumed by smaller plants. Finally, containerized plants are simply more attractive when they are proportional in size to the container they are grown in. These are many of the same reasons why growth of containerized flowering plants is controlled.

However, unlike floriculture crops, there are no plant growth regulators (PGRs) that can be applied to control growth. This article will focus on those factors — genetic, environmental, and cultural — which can be used to help control containerized herb growth.

The first step in controlling containerized herb size is taken when you select the cultivars to grow. In addition to flavor, foliage appearance, and a myriad of other factors, herb cultivars vary in their finished size. For containerized herb producers, selecting smaller or more compact cultivars to finish can help with meeting height targets. While compact cultivars are useful, they are not always available for each herb species. Basil, the most popular and widely grown containerized herb in North America, has a number of compact-growing cultivars that can be used for producing green-leaf sweet basil plants. Although not nearly as numerous, there are also compact dill cultivars available. However, for a number of herb species, there are no compact cultivars available to choose, and growth control will have to come by controlling the environment and culture, and not genetics. For many other species, there are such few cultivars available, and in general, these are much less compact varieties.

One cultural approach to take in controlling containerized herb growth is by controlling irrigation. The more “wet” herbs are grown, not only is the tissue softer growth, but plants are larger. Conversely, by restricting irrigation and growing containerized herbs on the dry side, plants are more toned for shipping and disease pressure is reduced while excess growth is inhibited. Growing dry can be a challenge, depending on the degree of dryness desired and how plants are irrigated. Growing slightly drier is achievable for both hand-watering and automated approaches.

Pushing the crops and growing with moderately to severely restricted irrigation is not as simple. For hand-watered crops, an extremely attentive and observant approach is needed in order to catch plants before they reach the permanent wilting point, which can cause irreparable damage to plants. Automated irrigation systems incorporating soil moisture sensors can be more successful when imposing a greater degree of drought stress, as plants can be irrigated when necessary. While reducing available water will suppress growth of nearly all herbs, the magnitude of effectiveness varies among species; drought-sensitive species respond more than more drought-tolerant species.

Modifying fertilizer practices is another effective strategy for controlling containerized herb growth. First, evaluate the nitrogen concentration being applied. Using a lower concentration of nitrogen — 75 to 100 ppm N — from a complete, balanced, water-soluble fertilizer can produce healthy-looking plants and more compact growth. Culinary herbs are efficient in nutrient use, so lower fertilizer concentrations can provide sufficient mineral nutrients to keep foliage appearing deficiency-free and result in adequate growth. In addition to reducing nitrogen concentrations, try to minimize phosphorous. Phosphorous contributes to stem elongation, and the same phosphorous restriction strategy commonly used for growing seedling plugs can also be used when finishing containerized herbs. Concentrations of ~10 to 20 P2O5 (the form of phosphorous in fertilizers) are sufficient to suppress unwanted growth and avoid any deficiency symptoms such as lower-leaf purpling.

Without any plant growth regulator to apply on container-grown culinary herbs, producers have to look for other growth-controlling strategies. While none of the approaches presented in this article will result in all the control you may need, an integrated approach using several techniques can.

Christopher (ccurrey@iastate.edu) is an associate professor of horticulture in the Department of Horticulture at Iowa State University.

As I walked the AmericanHort Cultivate‘21 tradeshow floor this past July — my first business trip and conference in more than eighteen months — my eyes scanned the booths seeking out tiny plants with enormous potential. Tiny edible plants, specifically, that make growing produce more accessible and successful for the indoor gardener. While micro-tomato cultivars have garnered the most focus in this area — and this was certainly evident by all the new micro-tomatoes at the show — I was excited to see new offerings of miniature pepper cultivars.

What do dwarf or micro-pepper cultivars for the hobby market have to do with commercial greenhouse production? Well, real estate is real estate, right? Space is always at a premium and yield per area is what it all comes down to. A challenge for those of you growing under glass or trying to expand your CEA’s offerings, is plant size and inputs. Fruiting plants, versus small leafy greens, are simply too big for many types of indoor controlled environments, not to mention more difficult to manage in terms of lighting and other resources. Larger crops also require a lot more labor when it comes to training them vertically, as well as lighting them properly. You can stack many racks of compact lettuces and leafy greens, but tomatoes and peppers? Not so much.

Peppers in greenhouse production are typically grown vertically, with two separate stems trained into an upright habit, much like vining tomatoes. While they don’t reach the heights that vining tomatoes do, nor need to be angled as many tomatoes are, they can still have a sizable vertical profile. And you can’t really pull the brittle stems down as you grow and harvest, like you can with tomatoes.

Most growers who are growing peppers under glass are strictly growing standard bell peppers. But with the growing popularity of hot and sweet peppers of all types, shapes and colors, you might be missing out on potential profits if you stick only to bells. Could dwarf and miniature cascading types of spicy peppers offer you both diversification and space-saving solutions without sacrificing yield?

Petite pepper player

At the Cultivate‘21 show, I was particularly impressed with the Prudac booth (http://prudac.com/), which was filled to the brim with their latest micro-tomato and micro-pepper varieties. In fact, they cornered the market on new dwarf edibles, having more than any other vendor at the show. I was instantly drawn in by their unique tiny tomato series, including tabletop Heartbreaker series, Sweet Sturdy series, the itty bitty Ponchi series, and the Pillar series for micro-trellising. PanAmerican Seed also had an impressive display of their new micro-tomatoes at the show. All these tiny tomatoes are not only perfect for the home grower market, but also offer super space-saving solutions for anyone wanting to get into the tomato game in smaller controlled environments.

Prudac also brought serious mini-pepper game, offering cascading basket types and compact narrow-growing peppers for trellising, with a mixture of sweet and spicy varieties. Their Peppers from Heaven series offers plants with a lush cascading growth habit; with plant height ± 15-25 cm / 6-10” and width ± 15-30 cm / 6-12”. Red and orange cultivars are currently available. These plants could make excellent options for hanging or other types of vertical hydro production. I was also intrigued by their Ponky Pepper ‘Spicy Jane,’ which they claim stays under 15 cm / 6” but can trail or train to a width of 60 cm / 24”. Now, Prudac states on their site that Ponky Peppers aren’t yet available in North America, but hopefully that will change.

But it was their slim-growing Pillar Peppers series that really had me doing a double take. These small, narrow, but sturdy little peppers appear to offer good production with less labor and space. Pillar Peppers seem perfect for high density culture and small pots (both for commercial production and home hobby growing). A series within a series, the Pillar Pepper Galaxy series offers red, orange and yellow cultivars with a mild spicy taste, with plants growing less than 20-25 cm / 8-10” tall and wide. All the dwarf peppers I inspected at the show appeared fruit-heavy with minimal branching.

If you’re a small grower with minimal space, and you’d like to branch out from leafy greens into fruits, miniature peppers could be a suitable place to start. Given that peppers are typically easier to grow — specifically more heat- and drought-tolerant — than tomatoes (not to say peppers growing in controlled environments don’t have their common issues), they might be a safer starter crop if you aren’t already growing or experienced with tomatoes.

Growing bigger profits in the new year just might mean growing small and spicy!

Understanding lavender’s potential

During a Monday session at Cultivate’21 in July, Peace Tree Farm’s Lloyd Traven went in depth on lavender, a perennial crop that has become more prominent in recent years. The session, which was unfortunately cut short due to a fire alarm at the Columbus Convention Center, featured Traven’s insight into a crop he and his team grow at Peace Tree.

“It has changed so much in the last decade,” Traven said. “It’s been an incredible evolution of the crop.” He later noted that, for big-box retailers, lavender has exceeded the 15% sales threshold and is now considered its own category in the broader perennial category.

>> Read the full story here: bit.ly/2VdwgGK.

Nature Fresh Farms announces partnership with University of Windsor

Nature Fresh Farms has joined the University of Windsor “in their long-haul vehicle transportation sustainability project to help achieve new advancements in energy efficient shipping.”

The purpose of this $160,000 project is to determine the impact of long-haul electric vehicles (LHEV) on Ontario’s electric grid. They will create an archetypal routing network by determining the most frequently traveled routes and then overlay the electric grid which will help determine how it will perform when managing a fleet of electric trucks.

>> Read the full story here: bit.ly/3fs6ipI

Got your lighting dialed in? Get ready for ePAR

A fundamental change in how we define photosynthetic active radiation (PAR) is afoot, at least if you believe two researchers who presented at Cultivate’21 back in July in Columbus, Ohio.

Utah State University’s Dr. Bruce Bugbee discussed some intriguing findings at Cultivate’21 from ex-graduate student Dr. Shuyang Zhen, a former student of Bugbee’s who is now a researcher in Texas A&M’s ag program.

Her work was recently published in a prominent scientific research report in June 2021, arguing that far red photons should be included in the definition of photosynthetic photons, and that standards should be developed to quantify the amount of those photons being provided by horticultural lighting.

>> Read the full story here: bit.ly/3A0S8Uc

Greetings, readers! You’ll find our annual State of the Industry research report for the CEA produce market issue (starting on page 16) inside this issue.

Our annual effort to uncover what’s helping and what’s hampering your operation revealed several interesting developments that occurred over the last 12 months. Here’s a small sample:

For one, I found it incredibly interesting that our survey group basically had no middle – 56% were either among the largest (100,000 sq. ft. under cover or more) or the smallest (from those less than 1,000 to those just under 2,499 sq. ft.) operations in the market. Couple that with the sales volume data – 65% either topped $1 million in annual revenue or secured somewhere between $1 to $9,000 in revenue this growing season – the picture becomes clear: in CEA produce, the big are scaling up and getting bigger, and yet smaller, localized operations are still finding opportunities.

The crops we grow under cover are evolving and shifting from year to year, as well.

Hot peppers – varieties like jalapenos, habaneros and the notoriously mouth-scorching Carolina Reaper (bred by the hilarious and equally brilliant Smokin’ Ed Currie down in the Carolinas – check out his PuckerButt Pepper Company YouTube channel) – have taken their rightful place among herbs, cucumbers, lettuce and tomatoes in the Top 5 most-grown crops under cover. It seems chefs and foodies and everyone else can’t get enough of these spicy, vibrantly colored chili plant hybrids. I must admit a bit of a bias here, as I annually produce a late-summer bounty of container-grown hot peppers for friends, family, co-workers, and even the chef at my local watering hole. It’s kind of my thing.

Conversely, you told us that managing the horticultural supply chain was a bear in 2021. We’re hoping that lessens in 2022 – but the early read we’ve gotten from talking with suppliers, breeders and growers is that unwelcome supply-side tension is probably here to stay.

OK, that’s all from me for now! Head over to page 16 and dig into the data … and if anything draws your eye, drop me a line at MGrassi@GIE.net.