Worms are annoying pests that can be tricky to fully eliminate from your garden. Some types of worms, like earthworms, are actually beneficial for your soil. But pests like tomato hornworms, cabbage worms, and cutworms can quickly damage your vegetable crops and be difficult to control. Here’s what you need to know about getting rid of stubborn worm infestations in your garden.
What are some common types of damaging garden worms?
There are a few main types of worms that can cause significant issues in vegetable gardens:
- Tomato hornworms – Large green caterpillars with white stripes that eat tomatoes, eggplant, peppers, and potatoes.
- Cabbage worms – Green caterpillars that eat cabbage, broccoli, cauliflower, kale and other brassicas.
- Cutworms – Plump brown or gray caterpillars that live in soil and chew through stems of seedlings.
- Root-knot nematodes – Tiny microscopic roundworms that infect plant roots.
The tomato hornworm and cabbage worm are especially notorious for severely defoliating plants in a short amount of time. Cutworms kill off young seedlings by chewing through the stems at soil level. Root-knot nematodes stunt root development and cause galls or knots in roots.
How can you identify worm damage?
Keep an eye out for these common signs of worm damage in the garden:
- Holes chewed in leaves, or leaves completely eaten – Hornworms, cabbage worms, and other caterpillars eat leaves
- Stems chewed through near the soil line – Cutworm caterpillars chew through seedling stems
- Wilted, stunted, or dying plants – Root-knot nematode damage
- Large green caterpillars on plants – Hornworms and cabbage worms
- Black excrement on leaves or near plants – Worm poop!
Inspect the undersides of leaves closely since many types of worms tend to hide out there while they eat and damage your plants. Also check near the base of plants for cutworm damage or signs of worms in the soil.
How can you prevent worms from becoming a problem?
The best defense is a good offense when it comes to stopping worms. Here are some tips to deter worms and prevent major infestations:
- Clean up crop debris after harvest to remove overwintering sites.
- Rotate vegetable crops to different areas of the garden each year.
- Cover plants with row cover fabric to create a physical barrier.
- Add beneficial nematodes to soil to parasitize worms.
- Use plastic mulch around plants to block worms from emerging.
- Put out pheromone traps to disrupt worm mating.
- Time plantings so vulnerable seedlings aren’t exposed at peak worm seasons.
Good cultural practices like maintaining healthy soil, watering at ground level, and not overfertilizing will also make your garden less inviting to worms.
How can you control an existing worm problem?
If worms have already infiltrated your garden, here are some effective control options:
Manual removal
Carefully pick hornworms, cabbage worms, cutworms, and other caterpillars off of infested plants and drop them into a bucket of soapy water to kill them. This works well for light infestations and is safe for organic gardening.
Sprays
Insecticidal sprays containing Bacillus thuringiensis (Bt) or spinosad can be sprayed directly onto infested plants to kill active worm pests. Multiple applications are typically needed. Take care to avoid beneficial insects.
Dusts
Diatomaceous earth dust sprinkled around plants will dry out and kill worms. Reapply after watering. Use horticultural oil sprayed onto plants to suffocate eggs and larvae.
Nematodes
Beneficial nematodes can be watered into soil to seek out and kill soil-dwelling worms. They are safe for organic growing.
Traps
Set pheromone or blacklight traps to capture and kill adult moths of cabbage worms, hornworms, and cutworms before they can lay more eggs. Or wrap stems of seedlings with cardboard or aluminum foil to create a barrier against cutworms crawling up from soil.
Resistant varieties
Plant worm-resistant vegetable varieties when available. Some resistant cabbage, broccoli, cauliflower, and tomato varieties have been bred to deter common worm pests.
When is the best time to control worms?
Be proactive! Treatment is most effective if started as soon as the first signs of worms are spotted. Don’t wait until plants are heavily infested and already damaged. For cutworms, protect young seedlings right after transplanting. For caterpillars like hornworms and cabbage worms, check plants closely through spring and summer and treat at the first signs of damage before they spread.
It’s also important to repeat treatments since most worm killers don’t impact eggs. So new generations can hatch out after treatment. Stay vigilant scouting for worms and retreat on a 7-10 day schedule if needed to catch newly emerged larvae before they get established.
What common home remedies kill worms?
Some common household ingredients may offer a solution for organic or DIY worm control:
- Salt spray – Dissolve 1 part salt in 4 parts water and spray plants, will dehydrate worms.
- Garlic spray – Purée garlic cloves in water, strain, and spray plants.
- Hot pepper spray – Blend hot peppers with water, strain, and spray on plants.
- Milk spray – Spray mix of 1 part milk and 4 parts water on plants, may impact enzymes.
- Neem oil – Derived from the neem tree, affects insect growth and repels pests.
- Diatomaceous earth – Sprinkle this dry powdered fossilized algae on soil and leaves.
Research effectiveness first, test these homemade remedies on a few leaves or plants before widespread use. Results can vary greatly depending on ingredients, mixtures, and pest pressure. Most will require multiple applications for best control.
How can you prevent worms from coming back?
After successfully getting rid of worms, be sure to take measures in future seasons to avoid repeating heavy infestations:
- Rotate vegetable planting sites.
- Clean up and destroy crop residue promptly after harvest.
- Consider using row covers over plants as a barrier.
- Let garden beds rest and grow cover crops or companions like onions/garlic.
- Add organic matter to improve soil health.
- Use pheromone traps to help control adults.
- Time plantings carefully based on peak worm activity periods.
- Inspect plants routinely and treat at first signs of worms.
Getting a handle early before worms have a chance to multiply and spread is key. Be patient and persistent! It may take a season or two to fully break the worm cycle but prevention combined with repeated organic treatments when needed can get your garden back to pest-free growing.
Conclusion
Worms can be challenging garden pests but there are many effective organic options available to both prevent and control infestations. The keys are early detection, prompt and repeated treatment, and good prevention practices between seasons. Combining manual removal, natural sprays, beneficial nematodes, and traps can safely knock back hornworms, cabbage worms, cutworms, and other stubborn worm pests. With persistence and a multi-pronged approach, you can evict worms and reclaim a healthy, thriving vegetable garden.