Whether you’re managing a commercial greenhouse or tending to a backyard herb garden, you’ll share something in common with every grower throughout the world: how to minimize the presence of pests. Pest control is a critical aspect of maintaining healthy plants and productive yields. While the intensity and economic impact of infestations may vary, the types of pests encountered are often surprisingly similar. Sap-sucking insects like aphids, whiteflies, and mealybugs can wreak havoc on tender new growth, while leaf-feeding caterpillars, thrips, and spider mites silently strip plants of their vitality. Even microscopic threats like fungus gnat larvae and root-damaging nematodes can pose significant risks, especially in humid, soil-rich environments like greenhouses or indoor grow rooms.
Luckily, nature offers a powerful line of defense: plants themselves. Many common herbs and ornamentals naturally deter pests thanks to their strong scents and pest-repelling compounds. In this article, we’ll explore the most common pests faced by growers of all kinds and introduce effective, plant-based strategies for keeping them at bay. Whether you’re looking to prevent infestations or supplement your current pest management plan, these natural allies can help you grow healthier, more resilient plants—without the need for harsh chemicals.
Common Pests for Professional & Hobbyist Growers
Both professional plant growers (e.g., greenhouse operators, nursery owners, market gardeners) and hobbyist gardeners encounter many of the same common plant pests, although the scale, impact, and management strategies may differ. While certain environments, such as greenhouses or seedbeds, will often be affected by their own specific pests, the most common ones across the board include:
- Aphids are small, soft-bodied insects (green, black, or red) that suck sap from new growth. This often leads to curling leaves, sticky honeydew, sooty mold and stunted growth.
- Whiteflies are tiny, white-winged insects that fly up when plants are disturbed. They also suck on the plant’s sap, leading to leaf yellowing, honeydew buildup, and virus transmission.
- Mealybugs show up as white, cottony clusters on stems, leaf joints, and roots. They suck plant sap, causing yellowing, wilting, and sometimes fungal infections.
- Thrips are slender, tiny insects (often tan or black) that feed on leaves and flowers. The main symptoms and concerns of a thrip infestation include silvery streaks or spots, distorted flowers and virus control.
- Spider Mites are microscopic mites that produce fine webbing under leaves. Damage: Speckled or bronzed leaves, leaf drop, general decline.
- Fungus Gnats are small black flies that lay eggs in moist soil. Their larvae feed on roots, which can cause fatal damage to seedlings and root systems, particularly in greenhouse or indoor environments.
- Members of the Caterpillar family include pests like cabbage worms, tomato hornworms, and armyworms. Infestations of these can lead to chewed leaves, fruit damage, and defoliation.
- Slugs and Snails are common pests in moist environments and container gardens. They leave behind slime trails and feed on leaves.
The Best Plants for Naturally Deterring Common Garden Pests
You may be surprised to discover that some of the most common household plants and herbs can help combat pests thanks to their natural deterrent qualities. Some of the most effective options include:
Basil
Basil emits strong aromatic oils like eugenol and linalool, which are great for repelling houseflies and mosquitoes. Eugenol is often used as a non-synthetic alternative to DEET, while linalool is effective against mosquitoes and ticks.
Lavender
Not only does lavender attract important pollinators, but it also contains both linalool and camphor. With a powerful scent, camphor has been used for years to repel pests such as moths, fleas, flies and mosquitoes – it’s even used to preserve books and paper from pest infestations.
Rosemary
Rosemary has a strong scent and is known as a great repellent for cabbage moths, carrot rust flies, aphids, whiteflies and thrips. It contains camphor, which carries a strong scent and cineole, which is a major component of eucalyptus oil and has great repellent properties.
Mint
With a strong scent and high concentration of menthol, mint has biocidal properties which deter ants, cabbage moths, aphids, and flea beetles. Take care when using it, though, as it can spread rapidly – it’s best planted in a container.
Marigolds & Chrystanthemums
Both of these flowering plants produce pyrethrin, a naturally derived insecticide unique to chrysanthemum and marigold plants. Boasting a rapid breakdown and being considered environmentally friendly, pyrethrins are great for repelling mosquitoes and aphids, but can cause issues for rabbits and potentially irritate human skin.
Citronella Grass
Citronella grass (which is often confused with lemongrass below) is effective against various insects, including mosquitoes. The grass contains citronellol and geraniol, scented compounds that repel a wide range of insects, including whiteflies and aphids.
Lemongrass
With a strong, citrussy scent and high concentration of essential oils like citronellal and citronellol, lemongrass repels mosquitoes and other insects. Either planted or used in a spray, it is a viable chemical-free option.
Alliums (Chives, Garlic)
Members of the allium family, Amaryllidaceae, emit a sulfur/onion odor that masks the smell of other plants, but is undetectable to humans. Popular choices include onions, garlic, shallots, leeks and chives, or decorative varieties loved for their globe-shaped heads in pinks and purples. A powerhouse of natural pest deterrence, alliums repel carrot root flies, aphids, and cabbage worms.
Explore Natural Insecticides
If you want an effective insecticide to prevent infestations of pests like mealybugs, you can explore and experiment with the different plants above. Alternatively, you might opt for a natural, chemical-free plant spray designed to combat specific pests while maintaining superior plant health. Whichever option you choose, it’s a good idea to be armed with a knowledge of plants and their helpful properties.
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