7 Best Horse Fly Repellent Plants For Around The Barn Old Farmers Swear By
Learn the 7 plants old farmers use to create a natural barrier against horse flies, keeping your barn and animals comfortable and pest-free.
Nothing ruins a peaceful summer day at the barn faster than the relentless buzzing and biting of horse flies. While fly sprays and traps have their place, integrating repellent plants creates a constant, natural first line of defense. Old-timers knew that a well-placed plant could do more than just look pretty; it could make the entire area less inviting to those blood-sucking pests.
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Using Aromatic Plants to Deter Biting Flies
The strategy here is simple: create a scent barrier. Biting flies, especially horse flies, navigate the world through scent, and they find the strong, volatile oils in certain aromatic plants confusing and repulsive. They’re looking for the smell of a warm-blooded meal, not a wall of lavender or rosemary.
This isn’t a magical force field, so let’s manage expectations. Planting a few herbs won’t eliminate every fly, but it can significantly reduce the number that hang around your barn doors, windows, and wash stalls. The goal is to make the immediate environment so aromatically unpleasant for them that they decide to move on to easier targets.
The key is strategic placement. Think about high-traffic areas where flies tend to congregate.
- Doorways and entrances: Plant in large pots or beds on either side of tack room and barn doors.
- Windowsills: Window boxes full of basil or marigolds can deter flies from entering.
- Patios and seating areas: Surround your resting spots with pots of scented geraniums or mint.
- Along walkways and fencelines: Brushing against these plants as you walk by releases their oils.
This approach is one layer in a comprehensive fly control plan. It works best when combined with good manure management and other control methods. But as a passive, low-effort tool, it’s one of the most effective you can have.
‘Genovese’ Basil: A Potent Aromatic Barrier
Basil is more than just a kitchen herb; its pungent, clove-like scent is deeply offensive to flies. We’re not talking about the mild sweet basil, but the potent, large-leaf ‘Genovese’ variety. Its high concentration of essential oils is what gives it such powerful repellent properties.
Because it’s an annual, basil offers flexibility. You aren’t committing a piece of ground for years to come. Plant it thickly in window boxes outside the tack room or in large containers flanking the main barn doors. Every time the wind blows or the sun warms its leaves, it releases a cloud of scent that flies hate.
The only real tradeoff is that you have to replant it each spring after the last frost. But this also gives you a chance to adjust your strategy year after year. For the sheer aromatic punch it delivers all summer long, ‘Genovese’ basil is a top contender for immediate, seasonal protection.
‘Munstead’ Lavender for a Calming, Fly-Free Zone
Lavender is a classic for a reason. Its fragrance is calming to people and horses but irritating to flies and other biting insects. The ‘Munstead’ variety is particularly useful in a farm setting because it’s compact, hardy, and an early, reliable bloomer.
This is a perennial, so think long-term with placement. ‘Munstead’ lavender is perfect for creating a permanent, low-maintenance hedge along a sunny walkway or the foundation of the barn. Once established, it’s quite drought-tolerant and will provide fragrant, fly-deterring protection for years.
The key to success with lavender is drainage. It absolutely despises "wet feet" and will rot in heavy, waterlogged clay soil. If your soil is poor, consider planting it in raised beds or on a sloped area where water can run off. The little bit of extra work upfront pays off with a beautiful, functional, and long-lasting plant barrier.
‘Arp’ Rosemary: Hardy, Year-Round Protection
For year-round structure and scent, rosemary is unbeatable. Its pine-like, medicinal aroma is a powerful fly deterrent. The ‘Arp’ variety is a standout because it’s one of the most cold-hardy, surviving winters in zones where other rosemary types would perish.
‘Arp’ grows into a substantial woody shrub, making it an excellent choice for a foundational planting around the barn or as a tough, evergreen border. The scent is most potent when the foliage is disturbed. Planting it along a path ensures that you, your dog, or even a horse brushing by will release its aromatic oils, constantly refreshing the scent barrier.
This is a plant for a sunny, well-drained spot. Like lavender, it doesn’t tolerate soggy soil. But its resilience to heat, drought, and even deer make it one of the most practical and permanent additions to a barn’s defensive perimeter.
‘Kentucky Colonel’ Mint Needs Careful Placement
Let’s be clear about one thing: do not plant mint directly in the ground. It is incredibly invasive and will spread relentlessly through underground runners, quickly taking over pastures and gardens. Its aggressive nature is a serious liability if not managed correctly.
With that warning out of the way, mint is also one of the most effective fly repellents available. The sharp, clean scent of a spearmint variety like ‘Kentucky Colonel’ is something flies simply can’t stand. The solution is containment. Plant it in large, durable containers like a stock tank, a half-barrel, or a tough-sided planter box.
A few large containers of mint placed strategically near manure piles or the wash stall can create an intense zone of scent that flies will avoid. You get all the repellent benefits without the risk of it taking over your property. Just remember to keep it well-watered, as mint in containers can dry out quickly in the summer heat.
‘Queen Sophia’ Marigold: A Colorful Deterrent
Marigolds are an old-school staple for pest control in vegetable gardens, and that same principle applies around the barn. Their distinct, musky scent, which comes from the chemical pyrethrin, is a known insect repellent. While many modern varieties have been bred for less scent, the classic, pungent French marigolds are the ones you want.
The ‘Queen Sophia’ variety is a perfect example. It’s a compact, tough, and intensely fragrant French marigold that produces beautiful reddish-orange flowers all summer long. They are workhorses, blooming continuously from spring until the first hard frost with minimal care.
Use them as annual fillers in pots, as a dense border along a path, or packed into planters. They thrive in full sun and tolerate poor soil, making them an easy, low-cost way to add both color and function to your fly control efforts. Their job is to stink, and they do it beautifully.
‘Powis Castle’ Artemisia’s Bitter Scent Shield
While other plants on this list are fragrant, artemisia offers a different profile: a bitter, camphor-like scent. This complex aroma, found in its silvery, fern-like foliage, is excellent for repelling flies and mosquitoes. It’s a smell that signals "not food" to insects in a very aggressive way.
The ‘Powis Castle’ variety is the best choice for a landscape setting. Unlike some of its relatives (like common wormwood), it forms a well-behaved, non-spreading mound. This makes it a reliable and predictable perennial that won’t get out of control. It’s also incredibly tough, thriving in heat, drought, and full sun, and is rarely bothered by deer or rabbits.
Plant ‘Powis Castle’ where you need a substantial, silvery accent that also works hard. Its fine texture contrasts beautifully with other plants, and its persistent bitter scent creates a wide repellent zone. A few of these shrubs can anchor a low-water, low-maintenance, fly-deterring garden bed.
‘Citronella’ Geranium: A Potted Patio Protector
First, a quick clarification: this plant (a Pelargonium) is not the true source of commercial citronella oil, but its leaves contain similar compounds and release a strong, citrusy scent when bruised. This makes it a fantastic, targeted repellent for smaller areas.
Because it’s a tender perennial—not winter-hardy in most climates—the ‘Citronella’ geranium is best grown in pots. This makes it the perfect protector for the tack room porch, the area around the cross-ties, or any outdoor seating area. You can move the pots exactly where you need them most.
The key to this plant is interaction. The scent is released when the leaves are touched or brushed by the wind. Placing a pot next to a doorway where you’ll brush past it frequently is a great way to keep the scent active. At the end of the season, you can simply bring the pot indoors to overwinter it for the following year.
Remember, these plants are a tool, not a cure-all. They work by creating an environment that is less attractive to flies, pushing them to go elsewhere. The most successful fly control programs are layered, combining smart planting with good sanitation and other management practices to give you and your horses a more peaceful summer.
