By: Liz Baessler
Chrysanthemums, or mums for short, are loved by gardeners and florists for their diversity of shapes and colors. There’s another reason you should be planting them all over your garden though: pest control! Chrysanthemums naturally produce a chemical called pyrethrin, and thanks to it, organic garden pest control can be as easy as scattering some mum plants.
Pyrethrin is the best of both worlds- it’s a neurotoxin that kills insects but does not harm mammals or birds. Insects prefer to stay away from it, so using mums to control pests can be achieved simply by planting them throughout your garden, especially close to plants that tend to be plagued by bugs.
To use a chrysanthemum for pest control, plant it about 1 to 1½ feet (30-45 cm.) from the plants you wish to protect. If using mums to control pests so sporadically isn’t for you, try planting a row of them as a border- it should still do the job, but give your garden a more cohesive feel.
If you don’t have the extra room for all these chrysanthemums in your garden, plant them in containers and place them wherever they fit.
If you want to take your organic pest control one step further, you can actually make pesticides from chrysanthemums. Simply pick the flowers when they’re at their fullest and leave them undisturbed in a cool, dark place with good air circulation until they dry. Grind them up into a powder and sprinkle it around your garden to kill and repel insects.
Another organic garden pest control can be made by steeping the flowers in hot water, allowing it to cool, and then sprinkling it on your plants. If this all sounds too intensive, there are commercial insecticides on the market derived from chrysanthemums. Buy yourself a bottle and fight off insects in a safe, organic, and biodegradable way.
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Chrysanthemum oil contains compounds called pyrethrins, which are used as natural pesticides. Pyrethrins can cause paralysis in insects on contact. Chrysanthemum oil by itself may not be strong enough to kill the insect, especially large insects like wasps. Commercial pesticides add other plant compounds to make the pyrethrins more toxic to wasps. Chrysanthemum oil can be effective for immobilizing wasps long enough to safely remove or destroy a wasp nest.
There are three insects that tend to wreak havoc on chrysanthemums. Aphids of multiple varieties are most commonly found on or near chrysanthemums. They’re small and round — often brown, black, green, or white — and leave behind a sticky substance known as honeydew. Some types of fungus will feed on this substance, so if you don’t notice the sticky texture you may notice small patches of fungus on your plant. They primarily target young plants or new growth, draining them of nutrients and resulting in shorter, stunted plants or occasionally death.
Mites, especially spider mites, are even smaller than aphids, making them easy to miss until they’re out of control. Look for small yellow spots on leaves and for leaves developing a dusty or filmy texture. In severe cases, mite infestations cause disfigured leaves and flowers that wilt and lose color. You can also identify mites, which are technically related to spiders, by the small, fine webs they leave underneath leaves.
Leaf miners are another problem, but the actual damage comes from the larva of these flies. The larva lives below the surface on the underside of leaves. They’re easily recognized from the molehill-like trails they leave. These trails, while individually not terribly significant, add up and spell disaster. An infestation of leaf miner larvae can kill the leaves of your chrysanthemum, which can weaken your plant overall.
Many plants are susceptible to attack only while young and tender. Those young leaves are much tastier than older leaves. The best way to deter pests is by a physical barrier to stop unwanted pests from getting into your garden in the first place. Here are some good options.
Dogs, rabbits, and other animals may be deterred by installing a fence securely attached at ground level. Larger garden pests, such as deer, may require tall fencing, which can get expensive. To avoid investing a lot in barriers, consider surrounding these plants with individual collars of fencing.
These lightweight fabric sheets drape over hoops or posts to cover plants without smothering them and allow light to pass through. Commonly used in commercial nurseries to protect tender plants from light frosts, row covers also protect vegetable crops from small animals and insects, such as birds, rabbits, squirrels, and caterpillars. Protect row crops with a tunnel-shape cloche created with wire hoops and row-cover fabric.
Row covers are most useful when plants are young and small, remove them as the plant grows and stems thicken, then turn to natural garden sprays, such as organic pesticides.
Sometimes you need to protect only one plant or row of plants. A cloche is a temporary cover sized and shaped to fit a particular plant. For single plants, make inexpensive cloches by cutting the bottom off of gallon plastic milk jugs and setting them over the plants. The primary danger with cloches is heat buildup on sunny days. Make sure to remove or vent the cloches so they don’t overheat your plants.
Cutworms are night-crawling pests that chew through stems at ground level they are particularly fond of young transplants of broccoli, cauliflower, and their relatives. Foil cutworms and other pests by forming 2- to 3-inch-diameter collars out of large index cards with the ends stapled together. Slip a collar over each transplant and push the collar an inch or so into the soil.
Sold as bird netting, this lightweight mesh protects berries and tree fruits from birds and pests like squirrels. Physical barriers are generally effective, but there are other options to keep pests away.
Some gardeners make homemade organic pest control insecticide for plants. These recipes rely on ingredients such as salt, mineral oil, or garlic. Use these natural remedies to fight off pests without causing harm to you or the plant. Just remember to reapply these natural garden pesticides frequently, especially in rainy climates.
Mealybugs have a waxy, white appearance and are hard to see on their own until they gather together and form a cotton ball-like infestation on your chrysanthemum plant. Insecticides don't work well with this pest. However, the population of pests can quickly be reduced by shooting your chrysanthemum plant with a strong stream of water.
Scales create scale-like growths on your chrysanthemum's stems and can weaken or kill your plant as the insects suck the juices out of your chryanthemum. Keeping your chrysanthemum well watered is key, as drought stress is one of the most important factors in a scale infestation. Natural predators, such as predatory wasps, often keep this pest under control, thus broad-range insecticides that might kill beneficial insects should be avoided. However, in severe cases of an infestation, mist all affected areas of your flower plant with any over-the-counter horticultural oil spray, such as those made with malathion.
This is my favorite homemade pesticide recipe. It’s simple, you can grow the two main ingredients, and it’s safe to use on any plant you eat. I wait a day or two before eating anything I spray with this pesticide because sometimes the taste will linger if you harvest on the same day as you spray. It does wash off, of course, and it doesn’t taste too bad, thanks to the mint and garlic.
Combine the garlic and mint in your food processor and pulse a few times Bring the 12 cups of water to the boil and add the mint, garlic, and pepper.
Boil for a minute and then let steep overnight. Next, strain into plastic spray bottles and add dishwashing liquid into each bottle.
I use this spray when there is any type of pest eating the foliage of my ornamental and edible plants. Don’t use this spray unless the plant is actively being attacked or you see the pests present.
Spray on both sides of the leaves and, after one or two applications, the bugs will die or leave for greener pastures.
I use oil-based pesticides when I have an infestation and I need to disrupt the life cycle of the pest. The oil will stick to the pest’s body, but more importantly, you want to target the eggs and the young so that as the older pests die, they’re not replaced. Over time, the bugs vanish entirely.
Mix the soap and oil in a bowl.
Take 3 tablespoons of this mixture and add to a cup of water. Pour this into a spray bottle, shake well, and attack that bug infestation. You can store the excess soap and oil mixture to use later.
Spray all over any bugs and pests you see. Make sure you spray both sides of the leaves and cover the bugs and eggs as best you can.
Next time you eat an orange or two, save the peels to make this incredibly simple homemade pesticide. I’ve been known to freeze skins until I’ve got enough for a bigger batch.
Place the peels in a bowl and pour 2 cups of boiling water over the orange peels and leave it to soak for 24 hours.
In the morning, strain the liquid into a spray bottle and add a few drops of dishwashing liquid before shaking the bottle to mix.
This is a fantastic pesticide for soft-bodied pests like slugs, mealybugs, and aphids.
This is an effective homemade pesticide, especially if you grow multiple tomato plants, as I do. Save the leaves as you pinch out the laterals of the tomato plant. It really doesn’t get simpler than that.
Chop the tomato leaves and place them in a bowl. Cover with hot water and allow to steep overnight.
In the morning, strain the mixture into a bottle and you’re ready to spray it on aphids or other pests.
This homemade pesticide is made up of my three favorite vegetables to grow and is suitable for use on roses and azaleas.
Place all the ingredients in a blender and blend into a watery paste. Let the mixture stand overnight.
In the morning, add a gallon of hot water and mix well. Strain into a spray bottle and use on roses, azaleas, and vegetables.
I’ve used this spray when my roses were covered in aphids and it worked well after only two applications.
This is a particularly powerful homemade pesticide that contains pyrethrum. Pyrethrum has always been my go-to spray when other pesticides don’t work. This is because pyrethrum affects the insect’s nervous system making it a perfect, natural knock-down tool.
It does take a little work, but if you dry as many chrysanthemum flowers as you can each year at the end of the season, you’ll have a ready supply every year.
Boil the flowers in the water for 20 minutes. Cool and strain into a spray bottle. This pesticide has a shelf life of about 2 months, but you could consider freezing some to use later in the year or make smaller batches to conserve the dried flowers.
Consider adding a little organic neem oil to this mixture for a longer-term effect.
A lot of people dismiss the idea of homemade pesticides, thinking the recipes aren’t powerful enough to work. Consider what farmers and growers did hundreds of years ago when commercial pesticides weren’t available. They made their own from natural ingredients that they had on hand, often based on what they grew at the time.
Give these pesticides a chance and keep your gardening as natural as possible. Give it a go, and if you have a favorite homemade pesticide recipe of your own, we’d love for you to share it with us.