01
Plants are close together
Leaves touch, benches repeat, and the next host may be inches away. That helps a local hot spot expand if the first infested plants are missed.
Greenhouse pest-control guide
Greenhouse Pest Control.
A greenhouse can turn one missed pest into several affected benches surprisingly fast. This guide shows you how to inspect by zone, read sticky cards, check incoming plants, trace hot spots, and build a repeatable response before a local problem becomes a greenhouse-wide problem.
Start here
How do you stop one pest from spreading through the greenhouse?
The answer is a repeatable inspection system. Greenhouses protect crops from weather, but those same protected conditions can also give whiteflies, thrips, aphids, spider mites, fungus gnats, powdery mildew, Botrytis, and other problems a steady environment and a lot of nearby host plants.
A strong program does not treat the greenhouse like one uniform room. Doors, vents, propagation areas, dry corners, wet-media zones, perimeter benches, interior benches, and receiving areas can all behave differently. Once we know where a problem starts, we can inspect the right plant zone, confirm the pest or disease, and decide whether the next action is sanitation, isolation, irrigation correction, climate adjustment, biological control, a contact treatment, or a combination.
Inspecting is the control system that comes before the spray program. Sticky cards help us see movement. Plant inspection confirms what is actually feeding. Records show whether pressure is rising or falling. Treatment works best when it is tied to those observations rather than applied blindly to every bench.
Why greenhouse pressure builds
Why greenhouse pests can spread so quickly.
A small outbreak becomes expensive when the system around it lets the pest move unnoticed. Four greenhouse realities explain why early detection matters so much.
02
Conditions stay favorable
Protected production can hold temperature, humidity, light, and moisture within ranges that also support pest reproduction or disease pressure.
03
New material keeps arriving
Cuttings, plugs, liners, transplants, pots, and growing media can introduce pests into an otherwise clean house. Receiving is a pest-management zone.
04
Hot spots hide in plain sight
A dry end bench can favor mites while a damp floor or wet-media area supports fungus gnats. A single greenhouse can contain several pest environments at once.
Greenhouse inspection map
Inspect the greenhouse by zone.
A fixed route keeps inspection from becoming a quick glance down the center aisle. Tap each zone to see what to look for and why it deserves a place in the route.
Common greenhouse pests
Learn the pest pattern before the outbreak spreads.
Each major greenhouse pest leaves a pattern: where it establishes, which plant zone it prefers, how it moves through production, and what clue often appears before the population becomes obvious.
Flying pest + underside population
Whiteflies often announce themselves when the crop is disturbed.
Adults can move between plants and are easy to pick up on yellow sticky cards, but the greenhouse diagnosis happens under the leaf. Check for adults and attached immature stages, then map which benches are producing the highest activity instead of assuming every captured whitefly came from the same place.
Establish first
Often on susceptible crops, new arrivals, perimeter plants, or localized benches.
Inspect
Leaf undersides, especially leaves near the active canopy.
Early clue
Adults fluttering up, honeydew, yellowing, or small pale immature stages underneath.
Monitor
Sticky cards reveal adult activity; plants reveal the resident population.
Flowers + tender growth
Thrips can be present before the damage is obvious.
Thrips move through protected crops as adults while larvae feed on plants. Flowers, buds, tender leaves, and tight plant structures deserve close inspection. Silvering, scarring, streaking, distorted flowers, or tiny black specks can be more visible than the insect itself.
Establish first
Flowering crops, susceptible cultivars, incoming material, and benches near entry points.
Inspect
Flowers, buds, new growth, leaf surfaces, and sheltered tissue.
Early clue
Sticky-card counts rise or fresh silvering appears before obvious plant decline.
Monitor
Yellow cards work broadly; blue cards can be useful when the focus is thrips.
Tender shoots + colony growth
Aphids can build quietly until new growth curls around them.
Winged aphids may appear on sticky cards, but most of the population will not. Open curled tips, inspect stems and leaf undersides, and look for sticky honeydew or cast skins. Aphids can multiply quickly on crops they favor, so a small colony deserves a location on the inspection map even if nearby plants still look clean.
Establish first
Tender growing points, soft stems, buds, and especially susceptible crops.
Inspect
New growth first, then undersides and stems immediately below it.
Early clue
Curling, puckering, honeydew, ants, cast skins, or a few clustered insects.
Monitor
Direct plant inspection matters much more than sticky cards for resident colonies.
Hot spots + magnification
Spider mites are a reason to inspect the hottest, driest zones separately.
Mites do not show up on sticky cards. Look for fine pale stippling that expands into bronzing, dull foliage, dusty undersides, and webbing in established infestations. Compare hot perimeter or vent-side plants with cooler interior plants; the greenhouse average can hide a mite-friendly microclimate.
Establish first
Warm, dry, stressed plant zones and known mite-susceptible crops.
Inspect
Lower and middle leaf undersides with a hand lens.
Early clue
Fine stippling before webbing. Webbing usually means pressure is already established.
Monitor
Use direct inspection and mark the exact bench or bay where stippling begins.
Root zone + moisture management
Fungus gnats tell you to inspect the growing environment below the canopy.
Adult gnats are easy to trap, but larvae develop in moist organic media and wet areas where fungi and algae thrive. Check the media surface, under benches, floor drainage, algae, spilled mix, and irrigation patterns. Incoming plants can also bring fungus gnats in their growing media.
Establish first
Damp media, propagation areas, algae, floor wet spots, and incoming pots.
Inspect
Soil surface, pot rims, roots, drains, under benches, and wet debris.
Early clue
Small dark flies near media or a rise on low-positioned sticky cards.
Monitor
Cards track adults; potato slices or direct media checks can reveal larvae.
Stems + petioles + sheltered plant surfaces
Scale insects can hide on greenhouse plants before the population looks obvious.
Scale insects spend most of their time attached directly to plant surfaces, so sticky cards are not the main scouting tool. Inspect stems, petioles, leaf veins, and protected junctions for stationary bumps or younger crawlers. Incoming and long-held plants deserve extra attention because a small resident population can be easy to overlook during a quick aisle check.
Establish first
Incoming plants, sheltered stems, long-held crops, and protected plant junctions.
Inspect
Stems, petioles, leaf veins, cane-like growth, and tight plant junctions.
Early clue
Stationary bumps, crawlers, yellowing, sticky residue, or localized plant decline.
Monitor
Use direct plant inspection because most scale stages will not appear on sticky cards.
Sticky-card monitoring
Sticky cards show movement. Plants show the infestation.
Cards are useful early-warning tools when their locations stay consistent from week to week. They work best as a map of flying activity, not as a substitute for looking directly at crops.
Example only: distribute cards by greenhouse zone, keep their positions repeatable, and add extra monitoring at doors, vents, receiving areas, susceptible crops, and fungus-gnat breeding zones.
Good for detecting
Adult whiteflies, thrips, fungus gnats, shore flies, leafminers, and winged aphids. Counts can show when activity is rising and where movement is concentrated.
They will miss
Spider mites, thrips larvae, immature whiteflies attached to leaves, wingless aphids, most scale stages, and many pests hidden inside plant structures.
Place by pest
Use canopy-level cards for thrips and whiteflies. Place some cards close to media or pot surfaces when fungus gnats are part of the question.
Do not read one number alone
A card count only makes sense with its zone, crop, date, previous count, plant symptoms, and direct inspection. Trends are more useful than an isolated total.
Quarantine & receiving
Check new plants before they enter production.
Incoming plants deserve their own inspection routine before they are mixed into clean benches. A receiving zone does not need to be elaborate to be useful; the goal is to create time and physical separation so a new pest is easier to see, identify, and contain.
01
Separate new arrivals
Hold incoming material apart from established production whenever your space allows.
02
Inspect plant + media
Check leaf undersides, buds, stems, roots or media surfaces, pot rims, and visible residue.
03
Monitor the receiving zone
Place sticky cards around new material and record what appears before plants move farther into the house.
04
Move only after the check
If a pest is found, keep that material mapped and separated until the next step is clear.
One house, several climates
Humidity and airflow change by zone.
A greenhouse sensor can report one number while individual benches experience very different airflow, leaf wetness, media moisture, and canopy density. Disease prevention gets stronger when the environmental observation is attached to a location.
Hot / dry end
Watch mite-sensitive crops, fast media dry-down, stressed leaves, and areas where warm air collects.
Humid / still pocket
Check dense foliage, condensation, slow-drying leaves, powdery mildew, Botrytis-like symptoms, and poor circulation.
Wet floor / media zone
Look for fungus gnats, algae, runoff, standing moisture, organic debris, and chronically wet containers.
Vent / door zone
Track outside insect entry, changing temperatures, direct airflow, and the first rows exposed to incoming air.
Greenhouse tips
Watch temperature, humidity, and airflow together. Keep fresh air moving through the growing space and run circulation fans consistently so humid conditions are less likely to encourage powdery mildew. Adjust watering based on the actual weather and how moist the growing media feels rather than following a fixed schedule.
Fungus gnats start where moisture lingers.
Adults on sticky cards are only one part of the problem. Fungus gnat larvae develop in moist organic media and wet greenhouse areas where fungi and algae are available. High pressure often points us toward irrigation, drainage, algae, spilled media, or incoming pots in addition to the insect itself.
Check the irrigation pattern
Which crops stay wet the longest? Which benches produce runoff? Which pots never seem to dry at the surface?
Check under benches
Standing water, algae, weeds, old media, and decaying debris can create breeding locations away from the crop canopy.
Check incoming media
Infested growing media can introduce adults and larvae with newly received plants.
Match treatment to life stage
Adult monitoring, media management, and a root-zone strategy solve different parts of the life cycle.
Lost Coast Plant Therapy can be used as a soil drench for fungus gnats according to the current instructions, but drainage and moisture management remain part of long-term control. Treating adults without correcting a wet breeding zone leaves the greenhouse system unchanged.
Remove pest and disease hiding places.
Cleaning is useful because it removes reservoirs, breeding sites, and the visual clutter that makes fresh symptoms harder to notice.
Dead leaves & crop debris
Clear senescent leaves, fallen flowers, culls, and old crop material rather than letting it accumulate under benches.
Weeds inside and outside
Volunteer hosts can shelter aphids, whiteflies, thrips, mites, diseases, and moisture-loving pests around production.
Algae
Algae is an important clue that a surface stays wet, and those wet areas are especially relevant when fungus gnats or shore flies appear.
Standing water
Fix chronic runoff and drainage areas instead of treating a wet-floor symptom as though it were only an insect problem.
Tools, trays & work surfaces
Clean reusable materials between crops or problem zones so routine greenhouse work does not move plant material and debris from one problem area into another.
Old plants & pet plants
Overwintered or non-production plants can carry pests into a new crop. Include them in routine pest checks instead of treating them as background.
Independent greenhouse evidence
What Cornell greenhouse trials found about Lost Coast Plant Therapy.
Lost Coast Plant Therapy is a minimum risk pesticide made with natural and organic ingredients that controls soft-bodied pests and powdery mildew on contact.
In Cornell greenhouse testing, the strongest treatment reported 95% +/- efficacy against western flower thrips and all soft-bodied insects and 96% +/- powdery mildew efficacy.
Commercial decision process
Build a consistent greenhouse pest-control protocol.
Consistency does not mean spraying every square foot automatically. It means the same evidence leads to the same action, the same application standard, and the same follow-up across every employee and greenhouse zone.
01
Map the hot spot
Record house, bay, bench, crop, symptoms, trap activity, and how far the issue extends beyond the first plant.
02
Confirm the target
Identify the pest or disease and note the life stage. Do not let sticky-card identity stand in for plant inspection.
03
Choose the action
Isolation, sanitation, climate correction, media management, biological control, contact treatment, or a coordinated combination.
04
Standardize coverage
If Lost Coast Plant Therapy fits, train for full saturation of the exposed target and follow the current official instructions.
05
Recheck the same zone
Return on schedule, compare trap counts and fresh plant symptoms, and expand or reduce the response based on what changed.
Commercial rule worth keeping: a treatment record without a follow-up observation tells you what was applied, not whether the greenhouse problem is improving.
Build a routine the whole team can repeat.
A greenhouse program works best when diagnosis, zone mapping, coverage, recordkeeping, and follow-up stay connected. Once a supported target is confirmed, use the current Lost Coast Plant Therapy instructions and make the same application standard easy for every grower or employee to repeat.
The goal is not to treat every bench the same. The goal is to make sure the same evidence produces the same response, then return to the same zone and measure what changed.
Greenhouse
application routine
Confirm target
Identify the pest or disease and note the life stage before treatment.
Map the zone
Record the greenhouse, bay, bench, crop, symptoms, and how far the issue extends.
Sticky-card context
Use trap counts for flying-adult trends, then confirm the resident population on the plants.
Contact coverage
Reach the exposed target deliberately, including dense canopies, leaf undersides, buds, stems, and lower zones when they are part of the diagnosis.
Fungus gnats
Pair current soil-drench guidance with media, drainage, algae, and moisture management.
Climate check
Record temperature, humidity, airflow, leaf wetness, and the microclimate around the affected zone.
Mixing & scale
Follow the current label and official Instructions page; use the commercial and acreage guidance that matches your facility volume.
Record the application
Log concentration, zone, crop, date, conditions, coverage, and the action taken.
Recheck
Return to the same plants and zone on schedule and compare fresh symptoms, active life stages, and trap activity.
Adjust the response
Expand, reduce, or change the plan based on what the follow-up shows rather than treating the whole house automatically.
Where the product fits
Where Lost Coast Plant Therapy fits.
When you confirm an applicable target such as whiteflies, thrips, aphids, spider mites, fungus gnats, powdery mildew, mold, or Botrytis, Lost Coast Plant Therapy provides contact control.
Growing at commercial scale? Turn your inspection records into a repeatable greenhouse program, then choose the product size and application approach that fits your facility. Lost Coast Plant Therapy offers farm and commercial sizes in addition to individual sizes.
✓
Contact matters
The target needs to be reached. Dense canopies, leaf undersides, buds, stems, and lower zones require deliberate coverage.
✓
Life stage matters
Map adults, larvae, eggs, or soil stages so the repeat schedule and application route match the pest being managed.
✓
Scale matters
We offer larger sizes for greenhouses and acreage, including 2.5-gallon concentrate quantities.
✓
Records matter
Log concentration, zone, crop, date, conditions, and the follow-up result so the facility learns from every application.
Questions growers ask.
What are the most common greenhouse pests? +
Whiteflies, thrips, aphids, spider mites, fungus gnats, shore flies, mealybugs, scale insects, and other pests can all establish in protected crops. The strongest greenhouse diagnosis starts by separating flying adults, plant-resident pests, and media-level pests, then inspecting the plant zone each one actually uses.
Why do greenhouse pests spread so quickly? +
Dense host plants, steady conditions, protected environments, and repeated crop movement shorten the distance between an infested plant and a new host. A missed receiving-area problem or localized hot spot can move into several benches before obvious damage appears.
How often should I inspect a greenhouse for pests? +
Use a regular inspection schedule and increase the frequency in propagation, receiving, known hot spots, or when trap counts and fresh symptoms rise. Smaller houses may benefit from quick daily visual checks. The important part is consistency: revisit the same zones often enough to see change early.
Where should sticky cards be placed? +
Distribute cards throughout the house and add attention near doors, vents, incoming plants, and susceptible crops. Canopy-level cards are useful for thrips and whiteflies; lower cards near pot or media surfaces help monitor fungus gnat adults. Keep locations stable so trends can be compared.
Do sticky traps control pests or just monitor them? +
Treat them primarily as monitoring tools. They catch flying or jumping adults but miss many non-flying life stages. A greenhouse can have spider mites, immature whiteflies, thrips larvae, or wingless aphids even when a sticky card looks quiet.
How do I inspect for thrips and whiteflies? +
For thrips, inspect flowers, buds, tender growth, and leaves for silvering, scarring, black specks, and slender insects. For whiteflies, gently disturb plants and turn leaves over to look for adults and attached immature stages. Compare the plant findings with nearby sticky-card activity.
How does humidity affect greenhouse disease pressure? +
Humidity is most useful when read with temperature, airflow, leaf wetness, canopy density, and location. Still, humid pockets can keep foliage wet or slow drying and increase disease pressure. Ventilation, circulation, spacing, irrigation timing, and sanitation all help change that environment.
How do fungus gnats start in greenhouses? +
They develop in moist growing media and wet greenhouse areas rich in fungi, algae, and organic matter. Incoming plants can also bring infested media. A rise in adults should trigger a media, drainage, algae, and irrigation inspection rather than an adult-only response.
Should incoming plants be quarantined? +
Yes, whenever the facility can create a practical receiving or holding area. Separation gives you time to inspect foliage and media, watch sticky cards, and identify a pest before new material is distributed across multiple crop zones.
How do commercial growers keep treatment consistent across a greenhouse? +
Use written zone names, pest confirmation, life-stage notes, standard mixing and coverage procedures, application records, and scheduled follow-up. The protocol should tell the team what evidence triggers treatment and what evidence shows that treatment is working.
Sources & further reading
Greenhouse references worth keeping nearby.
Green dots = independent greenhouse/IPM resources. Blue dots = official Lost Coast Plant Therapy information.
UMass Extension: Integrated Pest Management - sticky cards and greenhouse pest monitoring.
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UMass Extension: IPM Inspecting and Decision Making - pre-crop evaluation, weeds, drainage, algae, debris, and greenhouse records.
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UMass Extension: Vegetable Bedding Plant Production and Pest Management - sticky-card placement and direct plant inspection.
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UMass Extension: Fungus Gnats and Shore Flies - algae, moisture, breeding sites, and greenhouse sanitation.
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Michigan State University Extension: Integrated Pest Management in Greenhouse Crops - pest inspection and sticky-card monitoring.
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Oklahoma State University Extension: IPM Inspecting and Monitoring for Pests in Commercial Greenhouses.
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Cornell Greenhouse Horticulture: disease-management guidance on ventilation and high humidity.
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Lost Coast Plant Therapy: Cornell University greenhouse trial results.
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Lost Coast Plant Therapy: current mixing, foliar, soil-drench, infestation, greenhouse, and acreage instructions.
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Lost Coast Plant Therapy: contact action and coverage guidance.
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Lost Coast Plant Therapy: farms, commercial agriculture, and licensed cultivation.
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Lost Coast Plant Therapy: Issue Identifier for pest and disease follow-up.
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Want to learn more?
Keep diagnosing the exact greenhouse problem with pest-specific guides and the Issue Identifier.
Pest guide
Whiteflies
Adults, underside populations, honeydew, and contact coverage.
Pest guide
Thrips
Hidden feeding, flower damage, silvering, and greenhouse pressure.
Pest guide
Aphids
Tender growth, honeydew, colony detection, and root-aphid context.
Pest guide
Spider Mites
Stippling, bronzing, webbing, and hot/dry greenhouse zones.
Pest guide
Fungus Gnats
Larvae, moisture, greenhouse media, and soil-drench guidance.
Diagnostic hub
Issue Identifier
Move from a greenhouse symptom to a pest- or disease-specific resource.
Choose your size.
From a small greenhouse to commercial production, choose the Concentrate size that matches your application volume. Larger facilities can also explore farm and commercial options.
Lost Coast Plant Therapy
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12 oz
Mixes with water to create 12 gallons of application spray.
Lost Coast Plant Therapy
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32 oz
Mixes with water to create 32 gallons of application spray.
Lost Coast Plant Therapy
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1 Gallon
Mixes with water to create 128 gallons of application spray.
Lost Coast Plant Therapy
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2.5 Gallon
Mixes with water to create 320 gallons of application spray.
