Why We Don't Spray: How Indoor Farming Eliminates the Need for Pesticides

January 7, 2026

The science behind chemical-free greens — and what we actually do when problems arise

If you've ever wondered what's really on your grocery store lettuce, you're not alone. Pesticide residue on produce is one of the top concerns for health-conscious families, and for good reason.

At Grow Space, we grow all of our greens without synthetic chemical pesticides. But we don't expect you to just take our word for it. In this article, we'll break down why indoor vertical farming makes pesticide-free growing possible, what the research says about conventional produce, and exactly what we do when challenges arise.

What's Actually on Grocery Store Lettuce?

Let's start with the data. Every year, the USDA tests thousands of produce samples for pesticide residue. The Environmental Working Group (EWG) analyzes this data to publish their annual Shopper's Guide to Pesticides in Produce.

The findings on leafy greens are sobering:

86% of leafy green samples contained residues from two or more pesticides (1)
103 different pesticides have been detected on kale, collard, and mustard greens (2)
A single sample of leafy greens contained residues from 21 different pesticides (2)
Spinach has 1.8 times more pesticide residue by weight than other crops tested (1)
Neurotoxic insecticides including imidacloprid, bifenthrin, and cypermethrin are commonly found on leafy greens (1)

Perhaps most troubling: DDT, banned in the United States since 1972, was still detected in 16.2% of leaf lettuce samples in recent USDA testing (3). These are persistent chemicals that remain in our environment — and our food supply — decades after we stopped using them.

A History of "Safe Until Proven Harmful"

The pesticides on your produce today are approved by regulators. But history has shown us that "approved" doesn't always mean "safe."

DDT and the Near-Extinction of the Bald Eagle

Farmers began using DDT in 1939, a pesticide that killed insects by overloading their nervous systems. It seemed harmless to animals and was praised for stopping malaria and typhus outbreaks.

But DDT accumulated in the environment and built up through the food chain. Birds like the bald eagle began laying eggs with shells so thin they cracked before hatching. Entire populations nearly vanished.

Even after scientists raised alarms in 1962, DDT wasn't banned in the U.S. until 1972. It became a lesson in how something that seems safe can quietly cause lasting harm.

Chlorpyrifos: The Pesticide That Affected Children's Development

For years, farms relied on chlorpyrifos to protect crops from insects. It worked by attacking their nervous systems, similar to DDT, and was used on everything from corn to apples.

But scientists began finding links between chlorpyrifos exposure and developmental delays in children, especially those exposed before birth. The evidence grew, yet the pesticide stayed on the market for over 20 years after the discovery as legal battles dragged on.

It wasn't until 2021 that the U.S. finally banned it. By then, its story had become another reminder that regulatory action often lags far behind the science.

Still on the Market Today

Some chemicals with documented concerns remain widely used:

Glyphosate (Roundup), the world's most common herbicide, has been tied to gut microbiome damage and non-Hodgkin's lymphoma in multiple studies, yet it's still sprayed on lawns, fields, and public parks.
Atrazine, one of the most widely used herbicides in the U.S., has been shown to disrupt hormones and affect reproductive development in wildlife. It's banned in the European Union but remains common across America.

Each of these stories shares a theme: the science shows harm before regulations catch up.

How Indoor Farming Changes the Equation

At Grow Space, we've chosen a simpler path one that doesn't rely on waiting for regulations to protect you.

Indoor vertical farming fundamentally changes the pest equation. Here's why:

Physical Barriers Keep Pests Out

Our growing environment is enclosed. Walls, sealed doors, and controlled entry points create physical barriers that prevent the vast majority of pests from ever entering the facility.

In traditional outdoor farming, crops are exposed to insects, birds, rodents, and other wildlife that can damage plants and introduce contamination. In a controlled indoor environment, these risks are dramatically reduced.

The USDA's Agricultural Research Service confirms this advantage: "Vertical farming crops can often be grown without pesticides and are much less likely to be contaminated by pathogens harmful to humans." (4)

No Soil Means No Soil-Borne Problems

Many agricultural pests and pathogens originate in soil. By growing hydroponically, with plant roots suspended in nutrient-rich water rather than soil, we eliminate an entire category of problems.

Research published in Frontiers in Microbiology highlights the food safety advantages of hydroponic systems (5):

No soil contact eliminates soil-borne bacteria, fungi, and pathogens
Plants are protected from wildlife and farm animal contamination
Reduced need for washing post-harvest (excess moisture accelerates spoilage)
No chemical pesticides required in most operations

Controlled Environment Reduces Disease Pressure

In our facility, we control temperature, humidity, airflow, and light. This isn't just for optimal plant growth — it also creates conditions that are inhospitable to many pests and plant diseases.

Controlled Environment Agriculture (CEA) systems "often incorporate integrated pest management techniques, which reduce the need for chemical pesticides. Closed environments can also minimize the risk of pests and diseases." (6)

What We Actually Do: Complete Transparency

We believe you deserve to know exactly what goes into growing your food. Here's what we use (and don't use) at Grow Space.

Our Cleaning Practices

Between growing cycles, we clean our systems using:

Citric acid — A natural compound found in citrus fruits, used to sanitize our hydroponic systems
Dawn dish soap — Yes, the one with the duck. We use it to clean our trays, NFT channels, and growing pots
Hand washing — Every team member washes their hands before touching plants or equipment

That's it. No industrial sanitizers. No chemical treatments on the plants themselves.

When Pests Do Show Up: What We Have Done Before

We'd love to tell you we've never had a pest problem. But that wouldn't be true, and we believe in transparency.

In the past, we had an aphid outbreak. Here's exactly what happened and how we handled it:

First, we tried ladybugs. Ladybugs are a classic biological control for aphids, and we released them into our growing area. Unfortunately, it didn't work well for us. The ladybugs weren't effective enough to control the infestation.

Then we brought in parasitic wasps. Specifically, we used Aphidius colemani; tiny wasps (only 2-3mm long) that don't sting humans but are highly effective against aphids. These wasps lay their eggs inside aphid nymphs. The wasp larvae then consume the aphids from the inside, eventually emerging as adult wasps that seek out more aphids.

It worked. The wasp population established itself, controlled the aphids, and we resolved the outbreak without spraying a single chemical.

This approach — using beneficial insects to control pests — is called Integrated Pest Management (IPM). It's supported by extensive research and is widely used in greenhouse and hydroponic operations worldwide (7, 8).

When Mildew Appears

Humidity fluctuations can occasionally lead to powdery mildew on plants. If this happens, we use potassium bicarbonate mixed with soap.

Here's why we chose this approach:

Potassium bicarbonate is food-grade — it's the same compound used in baking as a leavening agent for cakes, cookies, and other foods (9)
It's OMRI-listed for organic production and approved for use on edible crops (10)
It's proven effective — potassium bicarbonate has been validated in over 200 university trials for powdery mildew control (10)
It works by changing surface pH — the alkaline solution makes leaf surfaces inhospitable to mildew spores without leaving harmful residues (11)

When mixed with soap and applied to affected plants, potassium bicarbonate simply raises the pH on the leaf surface, eliminating the mildew. It's not a synthetic fungicide — it's a baking ingredient.

What We Never Use

To be absolutely clear, we never spray synthetic chemical pesticides, herbicides, or fungicides on our plants. Period.

Frequently Asked Questions

Is hydroponic produce safer than conventionally grown produce?

Research suggests hydroponic systems reduce many contamination risks. A study in Frontiers in Microbiology found that hydroponic growing eliminates soil-borne pathogens and reduces exposure to wildlife contamination (5). However, food safety in any system depends on good practices. At Grow Space, we maintain strict sanitation protocols and never use synthetic pesticides.

What pesticides are commonly found on grocery store lettuce?

USDA testing has found over 100 different pesticides on leafy greens, including neurotoxic insecticides like imidacloprid, bifenthrin, and cypermethrin. 86% of samples contained residues from two or more pesticides (1).

How do vertical farms control pests without pesticides?

Vertical farms use physical barriers (walls and sealed environments) to prevent pest entry, eliminate soil which harbors many pests, and employ Integrated Pest Management (IPM) using beneficial insects when needed. The controlled environment also reduces conditions favorable to pests and diseases.

Is potassium bicarbonate safe to use on food crops?

Yes. Potassium bicarbonate is a food-grade compound commonly used in baking. It's OMRI-listed for organic production and has been proven effective in over 200 university trials. It works by raising pH on plant surfaces, not by leaving toxic residues (9, 10).

Are parasitic wasps safe to use in food production?

Yes. Parasitic wasps like Aphidius colemani are 2-3mm long, do not sting humans, and are widely used in commercial greenhouse and hydroponic operations for biological pest control. They're a natural, chemical-free alternative to insecticide sprays (7, 8).

Why isn't Grow Space certified organic?

USDA organic certification was designed primarily for soil-based agriculture. Hydroponic operations face different certification pathways that don't always reflect our actual practices. We believe in transparency over labels — which is why we tell you exactly what we use and don't use, so you can decide for yourself.

The Bottom Line

At Grow Space, we don't spray because we don't have to. Our indoor environment, physical barriers, and hydroponic systems eliminate most pest pressures before they start. When challenges do arise, we use biological controls and food-safe compounds — never synthetic chemical pesticides.

We believe clean food shouldn't require waiting decades for regulations to catch up with the science. That's why we've chosen a simpler path: walls instead of sprays, beneficial insects instead of insecticides, and complete transparency about everything we do.

Sources & References

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