Dahlias are absolutely gorgeous flowers that add a pop of color and beauty to any garden However, their good looks also make them a target for bugs and pests. As a dahlia lover, you want to keep your plants healthy and pest-free But you also want to avoid using harsh chemicals. So what should you spray for organic pest control?
Here is a list of the most common dahlia pests and the best natural ways to get rid of them.
Prevent Bugs from Reaching Dahlias
The most foolproof organic pest control for dahlias is preventing bugs from ever touching the plants in the first place.
Organza bags or sleeves are the best option for this. Place the bags over the dahlia blooms while they are still green buds. The fine mesh will keep out almost all pests while still letting air and sunlight pass through.
If you mostly grow dahlias for cutting, organza bags are great. But they might look a little silly in a garden for decoration.
Control Specific Dahlia Pests
If you don’t want to use organza bags, you’ll have to figure out what kind of bugs are in your garden and use sprays that kill those bugs. Here are some common dahlia bugs and organic control methods.
Grasshoppers
Grasshoppers are one of the toughest dahlia pests to control organically. They move fast and have hard bodies that resist sprays.
One organic solution is attracting birds to your garden. They love munching on grasshoppers. Add a bird bath or other water source. Chickens will also eat grasshoppers if your plants are large enough to withstand chicken activity.
For sprays, botanical insecticides with pyrethrins can kill grasshoppers. But you have to spray carefully and thoroughly since grasshoppers are quick to flee.
Thrips
Tiny thrips are a major nuisance for dahlias, especially light colored varieties. They feed on leaves and petals, leaving behind silver streaks and scarring.
Use yellow or blue sticky traps around plants to monitor for thrips. Control them with regular applications of insecticidal soap or neem oil sprays. Spinosad and pyrethrin insecticides also kill thrips. Rotate between different products to prevent resistance.
Bagging flowers provides the best thrip protection. Avoid growing early dahlias which are most prone to thrips.
Tarnished Plant Bugs
These small bugs pierce dahlia leaves and stems to suck out sap. They spread diseases as they move between plants.
Hang up yellow sticky traps in the plant canopy to catch tarnished plant bugs. Use traps carefully to prevent harming other animals.
Insecticidal soaps, neem oil, pyrethrins, and spinosad will also control plant bugs when applied regularly.
Leafhoppers
Like plant bugs, leafhoppers transmit dahlia diseases. They are tiny green, yellow, or brown insects that jump when disturbed.
Use yellow sticky traps as well as sprays of insecticidal soap, neem, or spinosad to control leafhoppers. Their populations explode in hot, dry weather.
Cucumber Beetles
These round-bodied beetles devour dahlia blooms and quickly defoliate plants. Watch for the yellow and black striped adults as well as the red or yellow spotted cucumber beetle larvae.
Neem oil, spinosad, pyrethrins, and insecticidal soaps can be sprayed to kill adults. Apply parasitic nematodes to soil to kill larvae. Completely covering flowers with bags provides the best protection.
Avoid planting dahlias near cucurbits, which attract cucumber beetles.
Aphids
Aphids cluster on dahlia shoots and undersides of leaves. These soft-bodied insects suck plant sap, causing stunted growth and discolored foliage.
Blast aphids off plants with a strong spray of water. Follow up with insecticidal soap or neem oil to kill them. Introduce ladybugs and other beneficial insects that feast on aphids.
Spider Mites
Hot, dry conditions cause microscopic spider mites to multiply rapidly. They form webs on dahlia leaves and cause stippling damage.
Apply sprays of neem oil, insecticidal soap, or horticultural oil to suffocate mites. Also release predatory mites to consume spider mites.
Dahlia Pest Spray Rotation
Whichever pests you battle, be sure to rotate between different spray products. Using the same pesticide repeatedly leads to resistance.
Ideally, alternate between products with these different active ingredients:
- Neem oil
- Insecticidal soaps
- Spinosad
- Pyrethrins
- Horticultural oils
This keeps the bugs guessing and avoids spraying any single pesticide too frequently. Carefully follow all label instructions for best results.
Maintain Plant Health
The best defense is a good offense when it comes to dahlia pest control. Healthy, vigorous plants can withstand more insect damage without suffering.
- Give dahlias full sun and high quality growing medium.
- Water and fertilize regularly to promote growth.
- Prune off any dead or diseased material immediately.
- Weed the dahlia bed to eliminate pest hiding spots.
With preventive measures and targeted organic sprays, you can enjoy gorgeous, pest-free dahlias. A garden teaming with beneficial insects and birds will also help reduce pests naturally.
Bugs Eating My Dahlias!
Below are the most common insect pests affecting dahlia plants in the garden:
- Thrips are thin pests with wings that have fringes. They hurt plants by puncturing the leaves and sucking out the juices. Thrips don’t usually kill dahlias, but they can change how they look by making the leaves stippled, dropping leaves, and slowing growth. Most of the time, pesticides don’t work because pests move so quickly from plant to plant.
- Spider mites: Spider mites are much too small to see with the naked eye. They are about the size of a grain of sand. A magnifying glass can help you find the pests, but most of the time you won’t need one because you’ll be able to tell them apart by the thin webs they make on the leaves. Spider mites are often more apparent during dry, dusty weather.
- Pests like Snails and Slugs—These pests can do a lot of damage to dahlias and other plants. They are easy to spot, though, because they chew big holes in leaves and leave slimy, mucus-filled trails behind them wherever they go.
- Caterpillars are the young stages of moths and butterflies. They don’t make slime, but they do chew holes in leaves like slugs do. Caterpillars often wrap themselves in leaves, and curled and rolled leaves are a sure sign that they have been eating your dahlias.
- Earwigs are small brown bugs with pincers that look like they could hurt you. They’re not as scary as they look, though. The most active time for these dahlia bug pests is at night, when they tend to stay hidden. Keep in mind that pesticides are ill-advised. Even though earwigs aren’t very attractive, they keep aphids and other more dangerous pests in check. Use a roll of newspaper or a short piece of old garden hose to catch them.
- Grasshoppers—Grasshoppers don’t harm dahlias too much, but they do eat the plants’ leaves sometimes. It is safe to get rid of these bugs with nosema locustae.
Dahlias 101 – Spraying
FAQ
What is the best insecticide for dahlias?
Recommended sprays: BioAdvanced 3-in-1, Monterey Garden Insect Spray, Orthene, Neem Oil, Sevin-5, Organocide, and Malathion. All organic sprays tend to work best for preventative care but are not as effective in treating a problem that already exists.
How do I keep bugs from eating my dahlias?
Keeping your dahlias consistently watered can help discourage them. Insecticidal soaps can temporarily reduce an outbreak. Read this article from the Missouri Botanical Garden to learn more about this bug and how to get rid of it: Controlling Thrips Outdoors.
What spray to use on dahlias?
Broad spectrum spinosad-based spray that controls most thrips, bores, leafminers, caterpillars, & moths. Works well for dahlias and other flowering plants.
Can I spray soapy water on dahlias?
If it is aphids, spraying them with water mixed with a little bit of dawn dish soap will kill them but not harm your dahlia!.