Slugs are the bane of gardeners’ lives, regularly topping surveys of garden pests. They munch the new growth of precious plants, demolish seedlings overnight and munch irregularly-shaped holes in leaves, stems, flowers, tubers and bulbs and potatoes, leaving their silvery slime trails behind.
Slugs are active for most of the year but are a particular problem in spring, when there’s plenty of young growth for them to eat. They are mostly active after dark, especially when it’s warm and damp. In hot, dry weather they bury themselves in the soil or hide in cool, dark places to avoid dehydrating.
There are over 40 species of slugs in the UK. Not all slugs eat live plants, however – many of the larger ones eat decaying or dead plant material and they are an important part of the composting process.
Despite your best efforts, some losses to slugs are inevitable. Accept that your garden is never going to be slug free, and find ways to work around this.
Make sure you prioritise the protection of the most vulnerable plants – all seedlings, new growth on most herbaceous plants, and all parts of especially susceptible plants such as delphiniums, hostas and dahlias. If you’re growing plants in pots, make sure there isn’t a ‘bridge’ of leaves from one plant to another, as slugs can travel from pot to pot this way.
Sow extra seeds so you have seedlings waiting in the wings to replace any that are eaten by slugs, and grow more than you need so you still have some crops left over after a slug attack. And add plenty of slug-resistant plants (see our list below) to keep damage to a minimum.
There are many options for controlling slugs. The best approach is to combine several methods, starting early in spring. Here are some ways to controlling slugs in your garden, some of them recommended in a survey of readers of BBC Gardeners’ World Magazine.
Garden slugs can be one of the most frustrating pests for any gardener Their slimy trails and large holes chewed into foliage are the calling cards of these soft-bodied gastropods African marigolds, with their tender leaves and brightly colored blooms, are a favorite snack for slugs. If you’ve noticed extensive slug damage on your marigold plants, it’s time to take action before they destroy your beautiful flowers.
Implementing a multifaceted pest management plan can help you gain the upper hand against troublesome slug populations in your garden. This comprehensive guide covers a variety of proven techniques to banish slugs from your African marigolds once and for all.
Understanding Slugs and How They Damage Plants
Before diving into control methods let’s quickly review some key facts about slugs
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Slugs are mollusks that use a muscular “foot” to glide along on a trail of slime. This mucus helps them cling to surfaces.
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They feed using a rasping, tongue-like organ called a radula to chew holes in foliage.
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Slugs thrive in cool, damp conditions and are most active at night or on cloudy, rainy days.
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During the day, slugs seek shelter in moist, dark locations like under boards, rocks, or dense ground cover.
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Slugs lay clusters of small, translucent eggs in protected sites which hatch into voracious juveniles.
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All life stages of slugs can severely damage garden plants by skeletonizing leaves and flowers.
Now that you understand slug behavior and biology, let’s explore tactics to protect your African marigolds.
Remove Daytime Harborages
The first line of defense is to eliminate moist, sheltered spots in your garden where slugs like to hide during the day. This forces them out into the open where they are more vulnerable.
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Remove boards, rocks, debris piles, weedy growth, or dense ground covers near plants.
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Prune back overgrown plants to improve air circulation and reduce humidity.
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Keep the garden tidy by clearing fallen leaves/fruit/flower heads where slugs could lay eggs.
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Mulch should be applied thinly since deep mulch retains moisture slugs need.
Manage Water and Soil Moisture
Slugs require damp conditions to thrive. Reducing moisture makes the habitat less hospitable.
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Water plants in the morning to allow time for foliage to dry out by evening.
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Use drip irrigation or soaker hoses instead of overhead watering when possible.
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Improve drainage in heavy soils and avoid overwatering.
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Allow the top few inches of soil to dry slightly between waterings.
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Position susceptible plants like marigolds in full sun to keep soil drier.
Use Physical Barriers
Physical barriers can block slugs from reaching your plants. Install barriers around seedlings or susceptible flowers.
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Copper foil or tape emits a tiny electric charge that deters slugs.
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Diatomaceous earth sprinkled around plants cuts into slugs’ soft bodies. Reapply after rain.
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Crushed eggshells also form a sharp, abrasive barrier for slugs.
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Place potted plants on overturned saucers filled with water to create a moat.
Set Out Traps and Baits
Traps and baits draw slugs in where you can dispatch them. Be sure to check and empty traps daily.
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Beer traps – Bury jars up to the rim filled with cheap beer to attract and drown slugs.
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Yeast traps – A mixture of water, flour, sugar, and yeast ferments, luring in slugs.
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Lettuce or cabbage leaves – Place these baits around the garden overnight and collect slugs from underneath in the morning.
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Sugar and bran bait – Mix 1 cup bran flakes, 1 tbsp sugar, and 2 cups water. Draws in slugs which bloat and die.
Control by Handpicking
One of the most effective ways to eliminate slugs is by handpicking them from plants. Get into the habit of regular evening slug patrols using gloves and a flashlight. Knock slugs into a bucket of soapy water to dispatch them. Be sure to check the undersides of leaves and inside flower blooms where slugs like to hide.
Use Slug-Killing Nematodes
Beneficial nematodes are microscopic worms that prey on slug eggs and newly hatched slugs in the soil. Phasmarhabditis hermaphrodita is a species sold for slug control. Apply nematodes to moist soil when slugs are beginning to appear. They provide biological control of young slugs.
Apply Slug-killing Products
Iron phosphate and sodium ferric EDTA baits are two slug-killing products approved for organic gardening. Sprinkle baits around plants in the evening, targeting areas with slug damage. As slugs ingest the bait, it disrupts their ability to feed, eventually causing death. Reapply baits after rain.
Exclude with Row Covers
Floating row covers of spun polyester or polypropylene fabric allow air, light, and water through while keeping slugs off plants. Drape covers directly over plants and anchor the edges with rocks, boards, or garden staples. Remove covers periodically to handpick any slugs that may be hiding inside.
Cultivate Natural Predators
Promote beneficial predators like garter snakes, ducks, toads, and ground beetles which feed on slugs. Avoid using broad-spectrum pesticides that might kill these helpful slug predators. Creating a diverse garden ecosystem supports natural biocontrols.
Trap Crops
Some plants seem to be more irresistible to slugs. Use these as trap crops to draw slugs away from prized flowers. Lettuce, cabbage, marigolds, and dahlias work well. Check trap crops daily and dispose of any slugs found on them.
By implementing multiple organic tactics to deter, trap, and kill slugs, you can protect your African marigolds from damage. Consistent prevention and control will discourage these pesky pests from ruining your garden.
Create a slug-free zone
It’s impossible to eliminate slugs from your whole garden, but you could create a small zone that you aim to keep slug free. Young seedlings and plants are by far the most vulnerable to slug attack, so prioritise the area where they grow, such as the area in and around a cold frame or a raised bed. Place fabric or mesh at the base of your pots before filling them with compost, so that slugs can’t gain entry from underneath them. Delay planting out seedlings until they have reached a decent size – they are more likely to withstand slug damage. Don’t overfeed young plants in spring, as this can create lush, leafy growth that slugs love.
Then deploy a number of the methods outlined below to keep the area free of slugs.
Water in the morning
This ensures that the soil has dried out by the evening, when slugs are most active. Wet soil at night can create a slug highway between plants.
Copper rings can be effective slug deterrents – if a slug tries to cross one it receives an ‘electric shock’, forcing it back. Put rings around vulnerable plants such as hostas – bury them deep as slugs may reach the plant from underneath.
Some gardeners also swear by sticking copper tape around the rim of pots, although a recent trial by the RHS found this to be ineffective. Research is ongoing, however.
- Buy copper rings from Crocus, Dobies and Suttons
Marigolds & Slugs
FAQ
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