Mixed Light & Outdoor: What Actually Determines Success

Front Row Ag Technical Specialist Tyler Simmons joins founders Matt Curran and Egan O'Keefe to discuss the operational strategies driving success in commercial outdoor and mixed-light cultivation. Drawing from real-world experience, they cover:

• Common greenhouse design mistakes that increase production costs
• Why trying to achieve indoor-level environmental control outdoors can reduce profitability
• Using Daily Light Integral (DLI) to plan around seasonal conditions
• Differences between natural sunlight and indoor lighting
• How plant size and spacing affect labor efficiency
• The benefits and trade-offs of in-ground versus container cultivation
• Why soil and water testing should guide fertilizer decisions
• Managing EC, sodium, pH, and water quality in outdoor systems
• How silica supports plant resilience under environmental stress
• Water temperature, pathogen pressure, and enzyme use in soil-based production

Transcript:

One of the biggest factors in successful greenhouse cultivation is something that's decided long before the first plant goes into the building.

It starts with greenhouse design.

For a greenhouse to perform well, all of its environmental systems need to be properly sized for the building itself. That includes heaters, exhaust fans, gable fans, evaporative cooling pads, and every other component responsible for controlling the climate.

A lot of growers run into problems because they don't fully account for the size of the greenhouse, the number of plants they'll be growing, their irrigation strategy, and ultimately how they're going to manage humidity efficiently.

Those decisions determine whether the greenhouse can maintain a stable environment without becoming prohibitively expensive to operate.

One thing we've seen repeatedly is growers trying to operate a greenhouse as if it were a fully indoor facility.

They want the same tightly controlled environmental conditions, but once they install enough equipment to achieve that level of control, they're often spending nearly as much money each month as they would operating an indoor grow.

The sweet spot is usually somewhere in between.

If you take advantage of the natural benefits of a greenhouse while supplementing only where necessary, you can often produce quality that's comparable to—or even better than—an indoor facility while spending significantly less on operating costs.

Lighting is another area where planning makes a tremendous difference.

Traditional greenhouse lighting designs often target relatively modest supplemental light levels, somewhere around 300 to 400 PPFD across the canopy.

For many greenhouse crops, that's perfectly reasonable.

The challenge is that not every greenhouse receives the same amount of natural sunlight.

A greenhouse in Maryland or North Carolina experiences a very different lighting environment than one in Arizona or another part of the desert Southwest.

If your greenhouse only has enough supplemental lighting to produce around 400 PPFD and then you experience extended periods of cloudy weather or short winter days, your total Daily Light Integral (DLI) may fall well below what the crop actually requires.

In some situations, growers may only receive 50–60% of the total daily light that an indoor facility consistently provides.

That raises an important question:

How do you compensate for those seasonal reductions in available light?

The answer starts with planning.

Before designing the lighting system, you should calculate:

• The months you'll be producing.
• Your expected lowest and highest DLI.
• How much supplemental lighting you'll need during each season.
• The balance between electricity costs and potential yield.

Those calculations should drive the lighting strategy—not the other way around.

DLI becomes one of the master variables governing photosynthesis and, ultimately, yield.

Facilities that skip this analysis often struggle because they install lighting without understanding how much natural sunlight they'll actually receive throughout the year.

Another interesting observation is that greenhouse-grown crops often express certain characteristics differently than indoor crops.

A lot of that appears to come from the full spectrum of sunlight.

Natural sunlight contains wavelengths and forms of radiation that artificial lighting systems don't fully reproduce.

Those additional wavelengths often allow plants to express more of their natural characteristics.

We've had opportunities to grow the exact same cultivars indoors, in greenhouses, mixed-light facilities, and outdoors across multiple states.

One consistent observation is that moving from indoor cultivation into greenhouse production often changes the plant's expression.

You begin seeing differences in overall morphology, terpene production, cannabinoid development, flavonoid expression, and plant structure.

Taking those same genetics outdoors often amplifies those differences even further.

The plants begin expressing characteristics that seem closer to how they naturally evolved under full sunlight.

Of course, more sunlight isn't always better.

There are times when outdoor conditions become too intense.

High light intensity combined with heat and low humidity can push plants beyond their optimal range.

That's when growers begin introducing tools such as shade cloth, evaporative cooling, or misting systems to reduce stress and bring environmental conditions back into balance.

Like every aspect of cultivation, it's ultimately about managing the interaction between light intensity, temperature, humidity, and plant physiology to keep the crop performing at its highest level.

One of the biggest differences between indoor and outdoor cultivation is the sheer number of variables you have to manage.

Indoors, you control nearly everything.

Outdoors, you're constantly adapting to changing environmental conditions.

For example, we've grown outdoor crops in both Oregon and Arizona, and the strategies couldn't be more different.

Early in the season, many outdoor growers actually install shade cloth to protect young plants from excessive light intensity and heat.

Later in the season, as days shorten and light intensity declines, that same shade cloth is removed so the crop can capture as much sunlight as possible during flowering.

Managing outdoor production often means continuously adapting to the changing seasons rather than maintaining one fixed environment.

Another major difference is plant size.

Traditional outdoor production often uses very wide spacing—plants may be positioned on 6- by 8-foot centers with several feet between rows.

Those plants can easily produce 8 to 10 pounds or more per plant, but that yield comes with significant labor requirements.

Large plants require:

• Extensive trellising.
• Frequent staking.
• Multiple rounds of pruning.
• Considerable labor during harvest.

Harvest itself becomes a logistical challenge.

The entire crop needs to be harvested before wet autumn weather increases the risk of mold and disease, often requiring a large temporary workforce over a very short period.

Indoor facilities rarely face that same challenge because production is spread throughout the year.

Harvests occur on a consistent schedule, allowing labor requirements to remain much more predictable.

That's one reason many outdoor growers have started moving toward a very different production model.

Instead of growing fewer, massive plants, they're planting many smaller plants directly in the ground.

Rather than allowing each plant to become enormous, they're establishing tighter spacing—sometimes only 2 to 3 feet apart—and initiating flowering while the plants are still relatively compact.

A plant might only be about 16 inches tall and 16 inches wide when flowering begins.

By harvest, the plants remain much easier to manage.

Many require little or no staking, and harvest becomes dramatically faster because workers are processing smaller plants instead of wrestling with giant bushes.

Growing directly in the ground also improves fertilizer efficiency.

Compared to inert media used in hydroponic systems, natural soils retain nutrients much more effectively.

They have greater cation exchange capacity and generally hold fertilizer in the root zone rather than allowing large amounts to wash away with runoff.

For some growers, that creates substantial savings.

Instead of shipping truckloads of fertilizer to support container-grown crops, they're able to achieve similar production using far less fertilizer by taking advantage of the soil's natural nutrient-holding capacity.

Another advantage is that the soil itself improves over time.

Rather than replacing media every season, growers can build soil fertility year after year through testing, amendments, and proper management.

After just a few seasons, many operations begin producing excellent yields per square foot while simultaneously reducing both fertilizer costs and labor requirements.

The process usually starts immediately after harvest.

Once the field is empty, the first step isn't fertilizing—it's soil testing.

Large agricultural operations routinely divide fields into smaller management zones.

Within each zone, soil samples are collected using a zigzag sampling pattern, combined into representative samples, and sent to a laboratory for analysis.

The results answer several critical questions:

• What is the soil pH?
• What nutrients are already present?
• What is the soil texture?
• How much sand, silt, and clay does it contain?
• How well will the soil retain water and nutrients?

Soil pH is usually the most important measurement because it directly affects nutrient availability throughout the growing season.

The existing mineral content is equally valuable.

For example, imagine the crop requires 200 pounds of nitrogen per acre during the season.

A soil test might reveal that 90 pounds are already present from the previous crop.

Instead of applying the full 200 pounds, you only need to supply the remaining 110 pounds, allowing fertilizer applications to be scheduled much more accurately throughout the season.

Soil pH often requires correction before planting as well.

If testing shows a pH around 5.2 or 5.3, large applications of dolomitic lime—sometimes 500 to 2,000 pounds per acre, depending on the soil—may be incorporated before the season begins.

The goal is to raise soil pH into a range where applied fertilizers remain highly available throughout the crop cycle.

Because many high-quality fertilizers gradually acidify soil over time, monitoring and correcting soil pH becomes an ongoing part of long-term field management.

Another major difference between outdoor and indoor cultivation is water quality.

Indoor facilities often start with municipal water, run it through reverse osmosis (RO), and then sanitize it before mixing nutrients.

Outdoor growers rarely have that luxury.

Most rely on well water, which often starts with an EC of 0.4 to 0.6 and contains significant amounts of dissolved minerals.

That's why, alongside soil testing, we always recommend a complete water analysis.

The soil and the irrigation water work together, so you need to understand both before building a fertility program.

For many outdoor operations, the biggest water quality issue is carbonate and bicarbonate alkalinity.

These compounds naturally push pH upward.

Rather than installing expensive treatment systems, many growers simply acidify their irrigation water to neutralize those carbonates before mixing fertilizer.

The acid converts much of the carbonate into carbon dioxide, which then escapes as gas, helping stabilize the irrigation water and making nutrient management much easier.

The water itself also influences how you manage the soil.

For example, a field that's never been cultivated before may naturally have a relatively high soil pH.

During that first growing season, some growers intentionally feed at a relatively low solution pH to offset the naturally alkaline soil.

As the years go by, repeated fertilizer applications gradually acidify the soil, reducing the need for those aggressive pH adjustments.

Beyond acidification, relatively inexpensive filtration systems can remove several undesirable components from irrigation water.

Sediment filters, carbon filters, and chlorine filters all operate at high flow rates and are practical for large outdoor irrigation systems.

However, sodium presents a much greater challenge.

Unlike chlorine, sodium generally requires reverse osmosis for effective removal.

Because RO systems become prohibitively expensive at the flow rates many outdoor farms require, growers often manage sodium through the soil instead.

If the soil drains well, excess irrigation can help leach sodium below the root zone.

If drainage is poor, amendments such as gypsum become an important management tool.

Gypsum helps displace sodium from the soil's cation exchange sites, allowing it to be leached away more effectively.

Water testing also reveals something many growers overlook:

Not every dissolved mineral is a problem.

Well water frequently contains meaningful amounts of:

• Calcium
• Magnesium
• Sulfur

Rather than treating those minerals as contaminants, they can often be incorporated into the fertilizer program.

If the water already supplies significant calcium or magnesium, fertilizer rates can sometimes be adjusted accordingly instead of adding nutrients the crop is already receiving.

Understanding what's already present allows for a more efficient fertility program.

Another product that's particularly valuable outdoors is monosilicic acid.

Most growers think of silica primarily for strengthening stems or improving disease resistance, but it may also play another important role.

In natural soils, plants are exposed to whatever elements happen to exist in that field—including trace heavy metals.

One way to reduce heavy metal uptake is proper pH management through lime and gypsum applications.

Another strategy is supplying nutrients the plant prefers to absorb.

Monosilicic acid appears to be one of those preferred nutrients.

When sufficient monosilicic acid is available, plants preferentially absorb silicon, reducing the opportunity for certain heavy metals to enter through competing uptake pathways.

Beyond that, silica provides the more familiar benefits growers already recognize.

Maintaining adequate silicon levels in plant tissue helps improve tolerance to biotic stresses such as powdery mildew and other diseases while also improving resistance to abiotic stresses including:

• Drought
• High light intensity
• Wind
• Environmental stress

Silicon strengthens cell walls and supports the plant's natural defense systems.

A useful analogy is human nutrition.

A healthy person eating a balanced diet generally resists illness better than someone under constant nutritional stress.

Plants behave similarly.

Healthier plants are naturally more resilient.

The same principle even applies to insect feeding.

Insects often cause more damage to weak plants because they must feed at many different locations to obtain the nutrients they need.

Healthier plants provide better nutrition with fewer feeding sites, so insects often cause less overall damage.

While silicon isn't a substitute for pest management, maintaining healthy, well-nourished plants creates another layer of resistance that becomes especially valuable in outdoor environments where plants are exposed to far greater environmental pressure than they would be indoors.

One challenge that's especially common in outdoor and greenhouse cultivation is something many growers don't think about until it becomes a problem:

Seasonal changes in source water.

Throughout the winter and spring, many facilities perform exceptionally well. Then, as summer arrives, plant performance gradually declines—even though the fertilizer program, irrigation schedule, and management practices haven't changed.

Often, the culprit is simply warmer irrigation water.

As groundwater temperatures rise, microbial populations naturally increase. The water entering the root zone contains a much higher bacterial and fungal load than it did earlier in the season.

From the grower's perspective, nothing has changed.

But one of the most important crop inputs has changed dramatically.

This is where building overall plant resilience becomes so valuable.

Products like monosilicic acid strengthen the plant, while establishing a healthy microbial community in the soil helps beneficial organisms occupy the root zone before harmful organisms have the opportunity.

Many growers already use products such as RootShield, Trichoderma, or similar biological inoculants for exactly this reason.

The goal is to establish a healthy biological community early in the season.

During cool conditions, the difference may not seem obvious.

But when irrigation water reaches 90–95°F and soil temperatures climb into the 80s, those beneficial microbes become much more important because they're already occupying the ecological niche that pathogens would otherwise exploit.

Building that biological community before stressful conditions arrive is far more effective than trying to solve the problem afterward.

Another important consideration is matching expectations to infrastructure.

Not every outdoor or greenhouse operation has the budget for reverse osmosis systems, water chilling, or sophisticated environmental controls.

Some facilities operate in startup markets with healthy margins.

Others are operating in mature markets where profits are extremely tight.

If a grower can't justify major infrastructure upgrades, the solution isn't necessarily to expect the same performance year-round.

Instead, it's often better to adjust production forecasts based on seasonal reality.

A greenhouse without advanced cooling systems may naturally produce its highest-quality flower during the cooler shoulder seasons rather than during the hottest part of summer.

Accepting those seasonal differences—and budgeting accordingly—is often a much more practical strategy than trying to force identical production through every month of the year.

In fact, some facilities have become more profitable by changing their production schedule entirely.

Rather than flowering through the hottest months, they focus production during spring and fall when temperatures are easier to control and supplemental lighting can compensate for shorter days.

Those shoulder seasons frequently produce better quality than peak summer, even with fewer hours of natural sunlight.

Greenhouse design plays a major role here.

Facilities equipped with multiple layers of shade cloth, misting systems, properly sized gable fans, and well-designed ventilation can continue producing successfully during extreme summer conditions.

More modest greenhouse designs often can't maintain the same level of environmental control.

In those cases, shoulder-season production frequently becomes the most profitable strategy.

The conversation then shifts to another tool that's especially valuable in outdoor soils: enzymes.

Natural soils behave very differently from hydroponic media.

One of the biggest differences is how tightly they hold onto phosphorus.

Even when phosphorus fertilizer is applied correctly, only 40–60% may actually remain available to the plant because much of it becomes chemically bound to soil particles.

This is where the enzyme phosphatase becomes useful.

Phosphatase helps release phosphorus that's become tied up in the soil, converting previously unavailable phosphorus back into a form the plant can absorb.

Instead of increasing fertilizer rates, the enzyme improves the efficiency of the fertilizer that's already present.

Because enzymes act on the soil rather than directly on the plant, they continue working throughout the root zone, improving phosphorus availability over time without creating additional nutrient stress.

The second enzyme, mannanase, works differently.

Plants naturally release sugars, starches, and other organic compounds into the root zone. These compounds help create the osmotic gradient that drives water toward the roots.

Mannanase breaks larger sugar molecules into smaller pieces.

By doing that, it increases the concentration of osmotically active molecules around the roots, strengthening the gradient that pulls water into the plant.

The concept is relatively simple:

• Plants naturally release sugars into the root zone.
• Mannanase breaks those sugars into smaller molecules.
• Those smaller molecules create a stronger osmotic gradient.
• A stronger gradient encourages more efficient water movement into the roots.

While the chemistry behind it can become complex, the practical benefit is improved water movement through the root zone.

Both phosphatase and mannanase are relatively simple enzymes, but they address two very different challenges:

• Phosphatase improves phosphorus availability by releasing phosphorus that's become bound to soil particles.
• Mannanase improves water movement by modifying sugars naturally present around the roots.

The conversation then turns to an interesting misconception about enzymes.

Many commercial enzyme products rely on living bacteria or fungi to produce those enzymes after they're introduced into the root zone.

That means their performance depends on the biology establishing itself first.

The approach discussed here is different.

The enzymes are initially produced by microorganisms in a laboratory, but then a purification process removes the living bacteria and fungi.

What's left is a highly purified enzyme preparation without living microbial cells.

That offers an important advantage, especially for irrigation systems.

Because the product doesn't introduce living organisms into the irrigation lines, it minimizes the risk of:

• Biofilm formation.
• Biological scaling.
• Microbial buildup inside pipes and emitters.

The goal is to deliver the biological activity of the enzymes while avoiding many of the maintenance issues that can accompany living microbial inoculants.

The conversation closes with a lighthearted joke about the enzyme's name.

Mannanase sounds a bit like "mayonnaise," leading to the obvious question of whether growers could simply pour mayonnaise into the root zone.

Of course, the answer is no.

The similarity is purely linguistic—the enzyme's name comes from the sugars it acts upon, not the condiment.

Humor aside, the broader point is that purified enzymes can improve nutrient efficiency and root-zone performance without adding living biology to the irrigation system, making them particularly well suited for outdoor production where irrigation maintenance and biofilm management are ongoing concerns.

One advantage of purified enzymes is that they begin working immediately.

Traditional biological products rely on living bacteria or fungi to colonize the root zone before significant amounts of enzymes are produced. That process depends on environmental conditions and the health of the soil biology.

With purified enzymes, you're applying the active molecules directly.

The enzymes immediately begin interacting with the soil rather than waiting for microorganisms to establish themselves.

That distinction is particularly important in large outdoor operations where conditions change constantly throughout the season.

Heavy rainfall, drought, high temperatures, and fluctuating soil moisture can all influence how quickly microbial inoculants establish themselves.

Purified enzymes remove much of that uncertainty.

Another benefit is compatibility with irrigation systems.

Many outdoor growers are moving increasingly toward fertigation and drip irrigation across large acreages.

Whenever you're running long irrigation lines, maintenance becomes a major consideration.

Introducing large populations of living microbes into those systems can increase the potential for:

• Biofilm formation.
• Organic buildup inside irrigation lines.
• Reduced emitter performance over time.

By applying purified enzymes rather than living microorganisms, growers can capture the benefits of enzyme activity while minimizing those irrigation maintenance concerns.

That becomes especially valuable in outdoor systems where filtration and water treatment options may be much more limited than they are in highly controlled indoor facilities.

Ultimately, successful outdoor production comes down to understanding that you're managing a very different system than an indoor grow.

Instead of starting with an inert substrate and purified water, you're working with:

• Native soil.
• Existing mineral reserves.
• Seasonal weather patterns.
• Variable water quality.
• Naturally changing microbial populations.

Those variables aren't necessarily disadvantages—they simply require a different management strategy.

Success begins with good planning:

• Test the soil before the season starts.
• Test the irrigation water.
• Correct soil pH when necessary.
• Build fertility around what's already present.
• Use amendments strategically.
• Improve nutrient efficiency wherever possible.
• Build healthy, resilient plants before environmental stress arrives.

When those fundamentals are in place, outdoor cultivation can produce exceptional quality while dramatically reducing production costs compared to more intensive cultivation systems.

Rather than trying to force outdoor production to behave like an indoor facility, the best growers learn to work with the environment—using good agronomy, careful planning, and efficient fertility management to let the field perform at its highest potential.