botanical illustration: natural pest control of bird eating snail

Organic Gardening Pest Control: Solutions for Gardeners of an Organic Flowerbed or Vegetable Patch

One of the most persistent challenges faced when in the organic garden is effective garden pest control with low effects on wildlife. In this blog post I'll give a bit of advice about the tools and methods that will control pests and protect your plants and crops without waving around spray wands full of pesticides. All while preserving wildlife and the natural ecosystem of your garden through regular organic techniques and strategies.


Table of Contents

Understanding Insects for Organic Pest Control

To effectively implement organic gardening pest control strategies, it is crucial to understand the life cycle of insects and their interaction with the environment. 

 an illustration of a pest's lifecycle

Insect Life Cycles

Every pest that invades your garden, from aphids and caterpillars to rodents and birds, has a life cycle comprising different stages - e.g. - egg, larval, pupal, and adult. Understanding these stages is crucial in disrupting their life cycle and effectively controlling their population.


Egg Stage:

Insects begin their life cycle as eggs. These eggs are often laid in secluded, sheltered areas near food sources. Organic control at this stage might involve physically removing the eggs or applying organic substances that deter the laying of eggs.


Larval Stage

This is usually the most destructive stage, where the larvae feed voraciously after hatching. Identifying and targeting this stage is crucial for organic pest control. Beneficial insects, such as ladybirds or lacewings, can be introduced on your plants, or attracted to your garden to feed on these larvae.


Pupal Stage

During this stage, the critters are dormant, often cocooned or buried in the soil. Although this stage is less destructive, it's a critical time for pests to be targeted before they emerge as reproducing adults through predators like soil treatment with a neem oil drench.


Adult Stage

Adult insects are often involved in the reproduction and can cause significant damage. Organic tools at this stage include traps, barriers, and natural predators like nematodes.


Interaction with the Environment

Garden Pests do not exist in a vacuum; they are a part of the ecosystem and interact continuously with their environment. Understanding these interactions is key to managing them effectively:


Food Sources

Insects are attracted to gardens as sources of food. By understanding what each species feeds on, gardeners can stop growing or protect these food sources, or even use them as bait in traps or grow as a sacrificial plant

 Slugs on a hosta being grown as a sacrificial plant as it is attractive to slugs

Natural Predators

Everything has natural enemies. Encouraging predators in your garden can help keep problem populations in check. This includes various wildlife - birds, beneficial insects, nematodes and even other larger animals.


Weather and Climate

The local climate and weather patterns play a significant role in pest life cycles. Some pests thrive in damp soil conditions, while others prefer dry heat. Understanding these preferences can help predict and prevent infestations.


Effective Organic Garden Pest Control Strategies

Now that we understand the life cycles and environmental interactions of pests, I’ll explore some effective organic garden pest control strategies:


Cultural Controls - Plants, Soil, Fallen Leaves and Diseases

These involve modifying your gardening practices to make the environment less hospitable to pests:

  • Plant rotation to disrupt pest life cycles

  • Incorporate companion planting to repel or confuse pests like wormwood and lavender, 

  • Consider growing some sacrificial plants to act as a diversion so you know just where to look for that pesky slug!.

  • Choose resistant cultivars and species.

  • Feed your soil with organic matter to maintain healthy nutrient profiles that will keep your plants strong and healthy - keeping diseases at bay helps your seeds to grow into strong plants

  • Removing diseased plants or debris as required due to an infestation.


Physical and Mechanical Controls Including Organic Pesticides:

These methods involve directly removing or blocking pests from your plants:

  • Hand-picking pests

  • Erecting physical barriers like sandpaper

  • Applying diatomaceous earth for ground level pests

  • Using water sprays to knock pests off plants (surprisingly effective!)

  • Applying special grease bands and tree barrier glues that protect fruit trees - prevention is often easier than cure..

  • Using traps to monitor and control small populations of specific pests - pheromone traps and slug beer traps and sticky papers to combat fungus gnats.

  • Applying natural pesticide emulsions like neem oil and insecticidal soap (check the label for correct useage)

 Grow plants in raised beds so it is easier to protect them from pests

Biological Controls:

This strategy involves using living organisms to control pest populations.

  • Introducing or encouraging beneficial predators - Other plants attract predators - hoverflies, ladybirds lacewings can decimate pest populations and growing a number of these different plants, help to encourage these natural predators to congregate in your garden

  • Biological controls can be purchased to deal with specific pests such as vine weevils and slugs

  1. Parasitoids: Such as Parasitoid wasps to combat mealybugs are unique insects whose immature stages develop inside or on a single host insect, ultimately leading to the host's death. Adult parasitoids might be free-living predators or feed on other substances like nectar or pollen. They are usually highly specialised due to the need to adapt to their host's life cycle and defences, making accurate identification vital for effective biological controlS.

  2. Pathogenic: Some pathogenic nematode species that infect insects slugs and insects have been created as a biological control. They enter the invertebrate’s body and release bacteria which causes the death of the invertebrate, the nematodes then multiply on the decomposing body while feeding upon it.

 An illustration of a ladybird eating aphids - an example of biological pest control

A Holistic Approach to Organic Gardening Pest Control

The most effective organic pest control strategy is often a combination of the methods mentioned above. This integrated approach not only targets the pests but also enhances the overall health and biodiversity of your garden.


Regular Monitoring: Keep a close eye on your garden. Early detection is key to preventing a full-blown infestation. Using the Integrated Pest Management method:


Identification: Properly identify the pests and understand their life cycle and habits. This will inform your control strategy and timing.

Intervention: Based on your understanding, implement a combination of the cultural, physical, biological, and botanical controls discussed above.

Adjustment: Be prepared to adjust your strategies based on what is or isn’t working. Organic pest control often requires a bit of trial and error.

Documentation: Keep records of what pests are present, what methods you've tried, and what the outcomes were. This information will be invaluable for your future gardening!


Combining Pest Control Methods

Understanding the life cycle of pests and their interaction with the environment is fundamental to effective organic pest control. By employing a holistic approach that combines cultural, physical, biological, and botanical strategies, gardeners can manage pests sustainably and effectively. Remember, the goal of organic pest control isn't just to eradicate pests but to maintain a balanced, healthy ecosystem where both plants and beneficial organisms thrive. With patience, observation, and a bit of know-how, your garden can flourish naturally, free from the detrimental effects of synthetic chemicals.


Real World Example: Organic Pest Control to Mitigate a (Worryingly Horrendous) Slug Infestation


As an organic nursery plant grower, maintaining the health and quality of my plants is pretty important. I don’t mind the odd nibble and maintain a live and let live approach for the  most part. However, after returning from a weeks holiday in camping in Wales (can I hear a whopwhop for Anglesey!) a very very large slug infestation had taken hold. Slugs, with their voracious appetites, were causing significant damage to a large proportion of my plant stock - the seedlings had been decimated and even older plants were suffering quite some damage.


Assessment of the Threat

I noticed telltale signs of slug activity: Damage ranging from irregular holes on leaves to seeds being bitten down to almost ground level, silvery slime trails, and weakened plant structures. The number of plants damaged was high, and the damage was quite bad in certain sections, particularly amongst the seedlings and new soft growth. I decided the threat was above my action threshold - a level of damage which was not natural, despite the fact I actively foster a habitat that encourages wildlife, with a lot of natural predators and I grow a lot of companion plants on purpose.

Decision-Making Process

The situation was quite urgent so Iimplemented a multi pronged approach. As an organic grower, it was crucial that the methods were sustainable, effective, and non-harmful to beneficial insects and the garden.


Organic Pest Management Tactics Chosen


Physical Practices:

  • Emery Paper barrier: I installed emery paper around the edges of raised beds, as slugs are deterred by the sharp surfaces of the sand paper.

  • Manual handpicking of any slugs I found 


Biological Controls:


  • Nematodes (Phasmarhabditis hermaphrodita): I applied the correct nematodes in the areas within the emery paper barriers. These microscopic worms invade the slugs, causing a fatal bacterial infection. This meant the slugs outside the barriers were unaffected as the nematodes were confined to the raised wooden troughs I grow in, minimising my harm to the overall slug population - natural predators in the garden will slowly pick them off. 

An illustration of slugs being preyed on by nematodes

Cultural Practices - Soil - Fallen LeavesDisease

  • Removal of Debris: I cleared all non-essential debris like leaves and stones where slugs might hide during the day.

  • Irrigation Management: I adjusted the watering schedule to ensure the soil surface wasn't constantly damp, as slugs thrive in moist conditions - my automatic watering system had been set to keep the compost too moist which may have encouraged the pesky molluscs


Monitoring and Adjustments:

  • Inspections: I conducted daily inspections for infestation symptoms, especially after dusk with a head torch (the powerful ones with the battery on the back of the head are great!), to  pick off slugs by hand and monitor the effectiveness of the interventions.

  • Adjustments: Based on these nocturnal; visits, I adjusted my strategy - I relocated beer traps to areas with more slugs!

 Slug beer trap - an effective pest control option


After my control effort there was immediate relief (both psychologically and for the plants!) after setting up the emery paper and more than a one handpicking session. The nematodes provided a long-term solution for any slugs I missed.Watering less and finally getting round to clearing the rock pile next to the hedge away helped to remove some of the safe spaces for slugs.


I do have a family and I do go away camping for the odd week so things like this will always happen - it really reinforced the value of regular monitoring and the need for a well thought out integrated pest management plan tailored to organic growing.


Finally - these Companion Planting tables may come in useful for natural pest control for your Vegetable Garden

 Check out this article with a detailed overview of companion planting

Full List of Plants That Deter or Repel Garden Critters:




Insects, including ants, cabbage looper, cabbage maggot, carrot fly, codling moth, flea beetles, whiteflies, the Cabbage White, and the Small White. Also repels mice, slugs and snails


Flies, including mosquitoes. Repels the carrot fly, asparagus beetles, and whiteflies.


tomato hornworm and cabbage worms.

Castor bean



ants, flea beetles, aphids, the Japanese beetle, squash bugs, weevils, the Colorado potato beetle, the cabbage looper, and cockroaches. May attract cats.


flying insects.


carrot fly, Japanese beetle, and aphids.


roaches, ants, the Japanese beetle, ticks, silverfish, lice, fleas, bedbugs, and root-knot nematodes.

Citronella grass

insects. May deter cats.


aphids and wireworms.

Common lantana



aphids, Colorado potato beetle, and spider mites.


the corn earworm.

Crown imperial

rabbits, mice, moles, voles, and ground squirrels.




aphids, squash bugs, spider mites, the cabbage looper, and the Small White.


spider mites, thrips, aphids, and whitefly.


aphids, the cabbage looper, and the Colorado potato beetle.


aphids, slugs, and snails.

Fever tea


Four o'clocks

Attract and poison the Japanese beetle.

French marigold

whiteflies, kills nematodes.


root maggots, cabbage looper, Mexican bean beetle, and peach tree borer.


leafhoppers, the corn earworm, and the Small White.


the cabbage looper and the Small White.




moths, scorpions, water scorpions, fleas, and flies, including mosquitoes.


carrot fly.



Lemon balm


Lemon thyme



carrot fly.

Lime basil


Mexican marigold

insects and rabbits.






squash bugs, aphids, many beetles, and the cabbage looper.


rabbits, the cabbage looper, and the Small White.


Repellent to many .


asparagus beetles.


aphids, cabbage looper, flea beetles, squash bugs, whiteflies, and the Small White.


aphids, tomato hornworm, asparagus beetles, leafhoppers, and squash bugs.

Pitcher plants

Traps and ingests insects.


cabbage maggot and cucumber beetles.


cabbage looper, carrot fly, cockroaches and mosquitoes, slugs, snails, as well as the Mexican bean beetle.

Russian sage

Repels wasps.


cucumber and flea beetles.

Sarracenia pitcher plants

traps yellowjacket wasps.


fleas, moths, ants, beetles, rodents, aphids, squash bugs, and the cabbage looper.

Spiny amaranth


Stone root


Summer savory

bean beetles.


ants, many beetles and flies, squash bugs, cutworms, Small White, and Cabbage White.


cabbage looper, cabbage maggot, corn earworm, whiteflies, tomato hornworm, and Small White.


carrot fly, flea beetles, and worms.


asparagus beetles.

Full List of Pests and Their Companion Plants That Effect Them 



Plants that Repel/Deter


Artemisias, Basil, Chives, Coriander, Dill, Fever tea, Geranium, Lavender, Nasturtiums, Peppermint, Petunias, Spearmint, Tansy, Thyme

Asparagus beetles

Basil, Chives, Common lantana, Rosemary, Spearmint, Tansy, Tomato



Cabbage looper

Artemisias, Basil, Catnip, Chrysanthemums, Dill, Geranium, Hyssop, Lavender, Lemon thyme, Nasturtiums, Onion, Oregano, Parsley, Peppermint, Rosemary, Spearmint, Thyme

Cabbage maggot

Artemisias, Radish

Carrot fly

Artemisias, Basil, Chives, Fever tea, Leek, Lettuce, Onion, Rosemary

Codling moth


Colorado potato beetle

Catnip, Chrysanthemums, Eucalyptus, Garlic, Rosemary

Corn earworm

Cosmos, Geranium, Rosemary, Thyme

Cucumber beetles

Rue, Radish


Spiny amaranth, Tansy

Flea beetles

Artemisias, Basil, Catnip, Fever tea, Garlic, Spearmint


Basil, Citronella grass, Lavender, Spearmint

Japanese beetle

Catnip, Chives, Crown imperial, Four o'clocks, Geranium, Hyssop, Leek, Rosemary, Spearmint, Tansy, Tomato


Geranium, Petunias




Artemisias, Crown imperial, Garlic, Narcissus


Castor bean, Crown imperial, Narcissus


Basil, Citronella grass, Fever tea, Lavender, Lemongrass, Lemon balm, Lemon thyme, Lime basil, Peppermint, Radish, Rosemary, Spearmint, Stone root, Tobacco




Chrysanthemums, Dahlias, French marigold

Peach tree borer


Root-knot nematodes



Catnip, Chrysanthemums, Rosemary


Garlic, Spearmint




Artemisias, Rosemary, Fennel

Small White

Artemisias, Catnip, Chrysanthemums, Dill, Geranium, Hyssop, Onion, Rosemary, Thyme


Artemisias, Rosemary, Fennel



Spider mites

Basil, Coriander, Dill, Epazote, Lavender, Peppermint

Squash bugs

Catnip, Chrysanthemums, Dill, Nasturtiums, Petunias, Spearmint, Tansy



Tomato hornworm

Borage, Petunias


Russian sage, Sarracenia pitcher plants

Water scorpions





Artemisias, Basil, Chrysanthemums, Citronella grass, Petunias, Peppermint





Back to blog

Leave a comment

Please note, comments need to be approved before they are published.