Natural Health Journals

Natural, Non-Toxic Ways to Kill and Deter Garden Pests

Garden Pests

Plus: Natural Ways to Kill Weeds

You spend a lot of time and effort planting and caring for your garden. Whether you have flowers, vegetables or fruits, or a combination, it’s exciting to watch the beautiful blossoms appear and to taste the lovely, delicious fruits and vegetables that your labor yields.

But then, you discover you have a problem. Aphids, ants, beetles or some other unwelcome critters are wreaking havoc on your precious garden!

You need to lose the intruders that are destroying your flowers or feasting on your produce. But as a nature-minded, organic gardener, you hesitate to go buy chemicals — poisons! — which will not only kill the pests, they will also kill the good, beneficial bugs, could be toxic to your family or pets, and would ultimately drain into the water supply … the very water that eventually comes out of your tap.

While the lion’s share of pesticide use in the United States, 80 percent, is in agriculture (with government, businesses and homes making up the remaining 20 percent), more than a hundred million pounds of these environmentally harmful chemicals are used in private homes and gardens every year. (Source: EPA statistics for 2007.)

But there is no need to add to the global pollution load, and even risk health hazards to your family and pets, when there are a number of simple, non-toxic ways to kill pests (and weeds) and discourage them from moving into your garden. Another great thing about using natural methods of pest control is that they are much cheaper than the toxic chemicals.

First, a brief overview of natural ways to prevent and discourage pests in your garden; then, we’ll discuss natural methods for treating infestations and keeping wildlife away from your plants.

The first steps toward keeping pests out of your garden involve prevention: a healthy garden will be less tempting for insects to move into. Regularly trim and remove dead or diseased leaves, flowers, plants and fallen fruits, and pull out weeds. Fallen leaves, flowers, fruit and weeds can act as breeding and hiding places for pests. Diseased plants can spread blight or infestation to healthy plants and are easier for pests to attack. Any diseased or weak-looking plants, stems, leaves, flowers or fruit should be thrown out in the trash, away from the garden. And remember to disinfect your gardening tools after trimming diseased plants.

Keeping a healthy soil that will nourish your plants also encourages healthy, thriving plants and discourages pests. Natural composting and mulching are two useful, great ways to nourish your soil; composting also improves its texture, and both increase its water-retention capacity. If need be, have your soil inexpensively tested by your county agricultural extension office, to determine if it needs nutrients and if it’s too acidic or alkaline for the plants you plan to grow or are growing. Then, add the recommended nutrients.

Being careful not to over-water or under-water your plants is also key to helping them stay strong.

To prevent common fungal diseases like “black spot” on the leaves of roses and other plants, grow your garden in open, sunny locations; this will dry foliage faster after waterings or rains. Avoid dense plantings and windbreaks, to allow for good air circulation. When the weather is cloudy, be extra careful not to wet foliage when watering. Water only the base of plants. When growing vine crops, like tomatoes and cucumbers, use trellises or other supporting structures, so that neither fruit nor leaves are in contact with moist soil.

Rotating crops is another good, natural way to keep the right levels of nutrients in the soil, which are used and deposited in different amounts by different plant families. Crop rotation also discourages insect infestations because by alternating where you grow your plants, you decrease the chance that any pests left in the soil from the previous crop will infest the new plants, as pests often attack plants that belong to the same families.

In addition to the above preventive methods, growing plants that will attract beneficial insects such as bees, butterflies, ladybugs, praying mantises and others, is a great way to naturally keep pest populations down. Think pollen- and nectar-rich flowering plants, of which there are a great many. It’s also a good idea to intermix your flower, fruit and vegetable plants with varieties that actively repel bad critters and foraging wildlife (some pest-repelling plants also attract beneficial insects, so, you could say they do double duty in the garden). Examples of these are aromatic herbs (sage, oregano, rosemary, mint, etc.), borage, yarrow, catnip, dill, onions, chrysanthemums, calendula, lavender, marigolds, citronella and others.

Natural Ways to Eliminate Infestations, Diseases and Wildlife from Your Garden

Okay, so, you’re hip to the above eco-friendly methods of pest control. But insects or other animals are overtaking your plants and you need an immediate solution.

Herewith, many of the most simple and clever we found in organic gardening websites and forums, where gardening pros post their wealth of knowledge and savvy growing tips.

To Get Rid of Slugs and Snails:

With the rainy season upon us, we thought we’d start with ways to fight slimy, icky slugs and snails, which make enormous holes on their favorite plants, gobble up seedlings and severely damage young plants — causing humans growing those plants to turn many shades of angry.

Sprinkle Salt: It doesn’t get any cheaper than this. Just sprinkle a thin line of salt on the edge of your garden beds or around plants that have been attacked by slugs or snails, and the slimy beasts will go someplace else. Salt dehydrates their flesh, so, they avoid it.

If you want to kill individual slugs or snails, you can sprinkle salt on each insect; but do not do this on the soil where you grow your plants, as you don’t want the rains or waterings to mix that salt into the soil. Too much salt will temporarily decrease a soil’s ability to grow plants by making water less available to plants’ roots. A light sprinkling of salt around a plant is okay. But avoid small mounds of salt all over your garden.

Tip: slugs and snails love the cabbage family, which includes kale, turnips and cauliflower, and they love radish leaves, lettuce, spinach and hostas (and seedlings).

Crushed eggshells: To us and our pets, eggshells are harmless; but to a mollusk that must slither on the ground to climb up your plants, they feel similar to broken glass. Spread some crushed eggshells around the stems of plants that are under attack, and the creepers will turn away. This method also works for caterpillars, which are the larva stage of butterflies or moths. Caterpillars eat a variety of crops, including tomatoes and other fruits and vegetables. As much as we don’t want to kill them, we must prevent them from destroying our plants.

Unbrewed, Caffeinated Coffee Grounds: Place unbrewed (unused) caffeinated coffee grounds around plants. The caffeine will repel or even kill slugs and snails. Used coffee grounds do not have enough caffeine to produce the same effect. Also, some say that spraying leftover caffeinated coffee on plant foliage will prevent slug and snail infestations; however, this doesn’t always work, and the caffeine residue may also harm beneficial insects, which you want to avoid doing.

Crushed Rock or Gravel: Putting a top layer of crushed rock or gravel around your plants’ stems will prevent slug and snail attacks, as the sharp stones are something the slitherers will avoid. Leave a little breathing and growing space between the rocks and plants’ stems.

Water with Ammonia: Make a solution of 4 parts water to 1 part ammonia, put in a spray bottle, and spray directly on any slugs or snails in your garden. It will kill them. The ammonia turns into nitrogen, which is naturally present in soil and serves as a fertilizer. Some sources recommend using half ammonia and half water, while others suggest using less ammonia than the 4 : 1 ratio above. But one thing everyone agrees on is that the diluted ammonia does not harm the plants, and since it evaporates or trickles into the ground, it will not harm beneficial insects in your garden.

So as to not attract ants to the dead mollusks, you’ll want to discard them in the trash or, if you have a compost pile outside, toss them in it.

Small Containers with Beer: Take small yogurt cups or similar containers and fill them with beer to an inch from the top. Bury them to ground level around plants that slugs or snails have attacked. The fermented yeast in the beer attracts the insects; it doesn’t have to be alcoholic beer. They’ll crawl in … and drown.

Pick Them Off: For the less squeamish gardener, gardening experts recommend picking off the slugs and snails from your plants, if they’re just a couple (we highly recommend wearing gloves!). But even so, you may want to follow up by sprinkling a little diatomaceous earth (see below) around the plant that was attacked, as other slugs / snails may follow the slime trails left behind by the ones you removed. If you keep an open composting pile in your yard, it is okay to toss the live critters in it; since slugs and snails eat decaying organic matter, they will likely stay put.

Keep Chickens or Ducks Around: If you have the space and your zoning laws allow it, keeping chickens and ducks around is a great way to get rid of slugs — grown chickens and ducks love to eat them!

Kill Different Insect Pests with Diatomaceous Earth:

This is a handy, natural, safe compound that kills many types of soft-bodied insects, including slugs, snails, mites, ants, cockroaches, fleas, ticks, bedbugs, earwigs, silverfish, centipedes and scorpions. It consists of fossilized remains of one-celled aquatic algae, diatoms. Their fossils are made of silica, a common mineral found in Earth’s crust and a component in sand, clay and some rocks.

For humans and pets, diatomaceous earth is harmless when applied correctly; but for soft-bodied insects, it’s like broken glass and it cuts into their outer shell and dehydrates them to death. DE has a white or off-white, soft-gritty consistency, and is widely available at garden centers.

With DE, less is more: it is best to sprinkle a very light coating of it in areas where you’ve seen insects you want to get rid of. Insects only need to get a little on them, for it to work. Sprinkle around your garden bed edges or around plant stems, to prevent creeping insects from getting on your plants. DE can also be used inside the home, such as on carpeting to kill fleas, or on kitchen cupboards, counters, etc., to kill cockroaches.

Two things to keep in mind:

1. DE is its most effective when the powder is dry, so, apply when garden soil (or other surface) is dry, and re-apply outdoors after a rain

2. Wear a protective mask when applying it, as DE dust that is lifted by wind can be inhaled and potentially injure lung tissue. While DE is non-toxic, it is not good to inhale the dust

Dish Soap and Water Kills Many Pests:

A lot of people are not aware of it, but plain dish soap and water is an effective killer of different garden pests, including ants, aphids, spider mites, thrips, whiteflies, psyllids, Japanese beetles and some scales, such as young scales and mealybugs. Soap and water kills these insects fast by penetrating their cell membranes.

To minimize the possibility of harming your plants, use natural or unscented liquid soaps, such as vegetable-based castile soap, Biokleen or unscented Ivory dish soap. One organic gardening expert online recommends a mixture of 1 teaspoon soap and 1 quart of water; another says a little more than 1 tablespoon soap per quart of water should be used (5 tbsp soap per gallon of water). Use a spray bottle to apply the mixture.

Some plants are more sensitive to soap sprays than others. You can spray a leaf on the plant to be treated, wait 24 hours, and check that the soap mixture did not harm the leaf. If there is any adverse effect, lower the amount of soap used. It is not recommended that you use more soap than the above ratios, as that could harm the plant.

Spray wherever you see pests, covering not only the tops of infested leaves, but the undersides and stems. For application to be effective, it must completely cover targeted insects. Pests within curled leaves that the spray doesn’t reach will not be eradicated. Repeat every week or so, if you continue to see pests on your plant.

The advantages of using liquid soap and water to kill garden pests are that it’s much safer than chemical pesticides, and that there is no residual effect — once the pests are killed, beneficial insects that come later will not be harmed.

Garden centers sell liquid insecticidal soaps that are specially made to kill insect pests. These soaps are less likely than dish soaps to do any harm to plants when mixed with water according to product instructions, but they cost more than dish soaps. And even insecticidal soaps often carry label warnings that some plants may be too sensitive for them. These plants may include hawthorn, sweet pea, cherries, plums and some tomato varieties.

Dry dish soaps and clothes washing detergents (whether dry or liquid) should not be used on plants because they’re too harsh. (Source: Colorado State University Extension.)

To decrease risk of plant injury from dish-washing soap or insecticidal soap, reduce recommended ratio of soap to water. Also, wash leaves with plain water two hours after having applied soap mixture.

Cooking Oil and Dish Soap for Insect Pests:

Soft-bodied garden pests, including aphids and mealybugs, can also be killed with a mixture of 1 tbsp cooking oil and a few drops of natural or unscented dish soap in a quart of water. Shake well and spray plant from above down, and from below up, covering the underside of leaves. The oil will smother pests that are sprayed.

For fruit trees: Blend 1 cup vegetable oil with 2 tbsp liquid dish soap. Add mix to 1 gallon of water, shaking well before use. Spray on all affected areas of your tree, covering undersides of leaves.

Kitchen Spices Repel Ants:

Inexpensive ant repellents, which you may have in your kitchen cabinet, include: ground cinnamon, red chili or cayenne pepper powder, paprika, black pepper and dried or ground peppermint leaves. Lightly sprinkle any of these on and around plants that are or may be attacked. You can also trace back where the ants are coming from and sprinkle a light coating of spice along that path. (For a project such as this, it pays to buy an extra-large container of spice. Some stores sell spices in pound-sized or even larger containers.)

Get Rid of Powdery Mildew and Fungal Diseases, Including Black Spot:

Academic sources and experienced gardeners alike agree that diluted milk is a great way to treat mildew and fungal diseases in plants, including “black spot,” which commonly grows on rose plants but can also develop in others.

As the name states, black spot is characterized by black spots that form usually on the upper surface of leaves; the leaf then starts yellowing and may fall off. The fungus may affect the stems, where it first appears purple, then black.

Below are two recipes from organic gardening sources online, for treating mildew and black spot in plants. Trim off diseased leaves and stems before spraying.

1. A solution of half skim milk and half water in a spray bottle

Spray solution on plant’s foliage in the morning, so it will dry fully before nighttime. Apply every 1-2 weeks or after a rain. As with pest treatments above, also spray undersides of leaves and stems. Discard any leftover mix and wash spray bottle with soapy water after each application.

Rake fallen leaves in your garden, as these are the main source of fungal spores (the cells through which fungi multiply).

2. A quarter cup of milk plus 4 drops natural or unscented liquid dish soap in a one-quart spray bottle, then fill with water and shake container

Apply to all plant’s surfaces once every two weeks or after rains. Discard leftover mix and wash spray bottle with soapy water after every use.

Baking Soda and Water for Fungal Diseases: Mix 2 tbsp of baking soda with 1 quart water in a spray container; spray affected areas of your plants. (Before application, remove leaves, stems and fruits that look diseased.) Repeat every few days until you eliminate the fungus.

Cooking Oil, Baking Soda and Dish Soap for Insects and Fungal Diseases: Mix 1 tbsp cooking oil, 2 tbsp baking soda and a few drops of natural or unscented liquid dish soap with 1 quart water in a spray bottle and spray affected areas every few days until problem clears.

Self-Rising Flour for Cabbage Loopers and Cabbage Worms:

Loopers and cabbage worms are in truth caterpillars — which, as mentioned earlier, are the larval stage of moths or butterflies. The looper later becomes a moth, and the cabbage worm, a butterfly.

Moths and butterflies are beneficial insects that sometimes eat pests like aphids, and they help to pollinate a garden; they usually don’t harm plants. But in the larval stage, they can instill horror in gardeners, as they tunnel big holes through cabbage leaves, lettuce, cauliflower, broccoli, spinach, tomatoes and flowers that they love. A big infestation of cabbage worms can kill plants in the Brassica family (cabbage family), especially when they’re young. The slithery buggers also leave countless dark little pellets of their feces on leaves — the leaves of produce you were planning to eat. Who wants any of that? One can’t well expect a gardener to stand by and let crops be lost to these critters.

If it’s just a couple of them, you can pick them off by hand or with a small stick and squash them — or relocate them, if you prefer. You should also search your plant for their small white, fluid-filled eggs, and squash or relocate them, too.

But if you start to see their droppings or the caterpillars themselves all over your plants, it’s time to fight the infestation.

Loopers and cabbage worms can’t digest flour. Self-rising flour is used because when the Sun comes out, it heats up the little crawlers and makes their guts explode. Not pretty, but certainly beats finding those big holes and droppings on your cabbage or other plants.

You can sprinkle the flour on affected crops manually, or put a cup of it in a paper bag, fold down the top and poke a few small holes at the bottom; then, sprinkle cabbage, broccoli, etc.

This method also kills tomato hornworms and cutworms. Sprinkle self-rising flour around and on plants being invaded by caterpillars. A light mixing of this flour into the soil around a plant’s stem will get cutworms that feed on the stems just beneath the surface.

Chili Powder for Rabbits, Moles, Voles, Mice and Squirrels:

If you have rabbits or rodents invading your garden, there are safe, non-toxic measures for that.

First, if you have a compost bin in your garden, insure that the lid is firmly in place and fits snugly.

Fences are a good way to keep rabbits and neighbors’ dogs from attacking your garden. The fence should reach low to the ground and be securely attached at the bottom, or rabbits and dogs can wiggle or dig their way under it.

But if you have smaller rodents like mice or moles digging up your plants, discourage them by sprinkling chili powder (also called chile, hot pepper or cayenne pepper powder) on the crops that they attack. Sprinkle a little of the fiery stuff on top of the plant, around bulbs and even on the soil. Sprinkling the soil will keep dogs and cats from digging up freshly planted soil, as they don’t like the hot powder, either.

Deter Deer:

Deer are beautiful creatures, but they can quickly eat up your plants — the average deer eats about 5 pounds of vegetation a day, and they’re especially fond of tender, new growths. So, it’s best to discourage deer from entering your garden.

Besides building a very tall fence, which may be cumbersome, or keeping dogs in your garden to scare away deer, milk is another effective deer deterrent.

Mix 1/4 cup of any kind of milk with 4 drops of natural liquid dish or castile soap; put in 1-quart spray bottle and fill with water. Shake and spray on the young new growth in your garden once every 10 days during the growing season (re-spray after a rain, once foliage dries). Discard any unused portion and wash sprayer after every application.

Two more ways to keep deer out of your garden:

  • Mix 1 tbsp natural liquid dish soap and 1 oz hot sauce (or 1 tsp hot chili or cayenne pepper powder); put mixture in 1-qt spray bottle and fill with water. Shake and spray on plants deer have been eating. Re-apply once a week or after a rain. Leftover mix will keep indefinitely
  • Hang a bar of fragrant body soap from the middle of a bush, to keep deer from eating leaves; deer are repelled by the scent. Rains or watering will keep soap bar fragrant

Natural Weed Control:

Maintaining a weed-free garden is important for limiting places where critters can hide. Plus, weeds rob your plants of nutrients and water that should be going to the plants. Control weeds early on, as it is easier to pull them out when they’re young than when they’ve established themselves and had a chance to produce seeds.

Try these four natural methods for getting rid of weeds:

  1. Pull them — and if they’re dandelion greens, eat them! (They’re packed with nutrients and make a great salad!) There is only one way to insure that a weed will not come back, and that’s to pull out its roots. Use a claw or other gardening tool to loosen soil from weed, and have a pair of gloves for that task alone, to avoid transferring weed seeds elsewhere
  2. Apply vinegar with a spray bottle; do this on a sunny day, as the Sun’s heat helps unleash vinegar’s plant-killing power. Vinegar can also harm other plants in your garden, so, you need to be careful where you spray it and avoid doing it on a windy day
  3. Pour boiling water in the center of each weed. Perennial weeds may require 2-3 applications; wear protective clothing and shoes, and be careful!
  4. Pour a little salt at the base of the weeds. Because too much salt is not good for the soil, avoid getting it on your other plants

By Cynthia Sanchez. A graduate of the University of Washington, Cynthia has extensive experience writing about health and wellness topics for different media.

One thought on “Natural, Non-Toxic Ways to Kill and Deter Garden Pests

Leave a Reply

Your email address will not be published.