The likes of aphids, thrips, spider mites and slugs can be a problem for home dahlia growers. Some of these pests are so small that they cannot be seen with the naked eye, but the devastation they cause can quickly become apparent.
If you are growing dahlias, there are natural preventive measures you can use to deter pests, and actions to take as soon as you discover an infestation. A good set of eyes and a quick course of action can ensure you don’t ruin your dahlia display for the summer.
What insects do dahlias eat?
Dahlias bloom from early summer until fall
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There is a large variety of dahlias that you can grow and enjoy in your flower beds or choose as part of a cut flower garden. However, all types of dahlias can be susceptible to pests that like to chew the leaves, petals or flower buds.
Zahid Adnan, experienced gardener and founder of The Plant Bible, claims that regular inspection of your dahlias is “critical” because pests can “quickly damage” your precious plants.
“If left unchecked, pests can impair the overall health of the dahlia plant, which can lead to stunted growth or even death of the plant,” he says.
“By monitoring your dahlias closely, you can identify pest problems early and take timely action to prevent the infestation from becoming out of control. Early detection also allows for a more targeted and effective treatment plan.”
We take a look at some of the most common dahlia pests and the damage they can do to your plants:
thrips – If you infect dahlias with thrips, they cause damage to the leaves and petals, causing leaf wounds and the leaves to turn yellow.
Manna Aphids are small insects that gather in large numbers on plants. Aphids are usually seen on dahlias on the undersides of the leaves, or sometimes on the stems. They cause foliage to become distorted or curled and can attract mold and other insects to the aphids they secrete
Spiders It can be difficult to see spider mites on dahlia plants because they are small, and you will need a magnifying glass to spot them. The leaves will become discolored, taking on a yellow tinge with a red band on the back of infected foliage. Spider mites start from the bottom up, with the oldest leaves being affected first
Earwigs The main problem with earwigs in dahlias is that they cause a lot of aesthetic damage, as they tear the flowers and bite the leaves. The edges will be bitten off and holes punched through the petals and leaves.
Slugs and snails – The characteristic sticky tracks as well as the leaves and stems are classic signs of snails or slugs eating dahlia flowers. These voracious and common garden pests can do serious damage to young, fresh growth soon after dahlias are planted in the yard.
Bugs capsid Dahlia plants are particularly susceptible to these diseases in late spring and early summer. Horticulture expert John Negus explains how these tiny, light-green insects suck the sap from the tips of growing shoots and cause real damage. He adds: “The saliva of these insects is toxic to plant cells, and as the young leaves at the tip of the shoots grow and expand, the damaged areas become distorted and torn into small holes, which then become rough.”
Al Zahid is a well-known figure in the field of horticulture, with extensive experience and hard-earned skills in the field of horticulture. As founder and editor of ThePlantBible.com, he delivers top-notch content and professional advice to fellow gardening enthusiasts on a daily basis.
John Negus
John has been a garden journalist for over 50 years and regularly answers readers’ questions Amateur gardening magazine. He has also written four books and given numerous lectures over the years on gardening.
Measures to prevent dahlia pests
Aphids suck sap from stems, leaves and flowers
(Image credit: Getty/Peter Shaw)
Planting dahlias in the best position and in good quality soil can help ensure that your plants are healthy and strong. Thriving plants will be more resistant to pests as well as dahlia diseases. Therefore, it is important to place your dahlias in a sunny location with fertile soil, ideally enriched with compost or well-rotted manure, which is well-drained. If you are growing dahlias in pots, location and soil will also be key areas you need to get right, as well as making sure any planters have holes in the bottom for drainage.
In addition to location, proper maintenance plays a role in combating potential pest problems. Proper watering, careful and proper feeding and removing any debris from around the dahlias will ensure that the plants are not stressed and do not provide a place for pests to hide. When you prune dahlias or dead dahlias, keep a close eye on any damaged parts as well and remove them from the plant.
Companion planting can be used to repel pests that may attack your dahlias. There are many pest repellent plants that can be used to discourage certain pests, such as marigolds, chrysanthemums, lavender and calendula are great options to deter many insects.
You can purchase lavender seeds and plants from Burpee
How do you treat dahlia pests?
(Image credit: Clive Nichols/Corbis Documentary/Getty Images)
Larger pests, including slugs and caterpillars, can be picked off by hand from plants, while smaller infestations can also be crushed by hand. Regular checking is recommended and this may mean going out in the dark hours with a torch, as slugs and snails feed at night.
Another simple way to get rid of aphids, or get rid of spider mites as well, is to remove them from your plants with a blast of water from a garden hose. There are also organic sprays or homemade insect sprays that you can use to control pests.
Garden Savvy’s John Erling says targeted chemical insecticides should only be used as a “last resort,” so he recommends some of the natural treatment options available.
“Insecticidal soaps or horticultural oils can be used to treat soft-bodied pests such as aphids, spider mites and thrips, suffocating them while being less harmful to beneficial insects,” he says.
Neem oil, an organic option, can help control a wide range of pests by disrupting their feeding and growth. Biological control can be introduced by releasing beneficial insects such as ladybugs and praying mantises into the garden to control pest populations.
There is also the possibility of using natural bacteria in the form of Bacillus thuringiensis to control caterpillars and their larvae. Any of these products are very specific to the insects they target and should be used with care. One example of this product is Caterpillar and Webworm Control, available on Amazon.
Tony O’Neill, an experienced gardener and author of Simplify Gardening, suggests a specific trick for getting rid of scissors. He says: “Scissors can be trapped using damp, rolled-up newspaper or straw placed near the base of the plant at night. They will hide there, allowing you to Get rid of them in the morning.
John Erling is president and co-founder of Garden Savvy, which provides software for gardeners and growers looking to make their gardening lives easier.
Tony O’Neill is an accomplished horticulturist, author, and educator. With a passion for simplifying gardening practices, he has inspired a wide audience through his popular YouTube channel and website Simplify Gardening.
common questions
How do I prevent slugs and snails from eating dahlia flowers?
There are several slug control methods that can be used to get rid of slugs and prevent them from causing damage to your dahlia plants. This involves creating a barrier around plants or pots through the use of copper tape, diatomaceous earth, crushed eggshells, or coffee grounds. Other popular methods include using slug repellent plants, beer traps, or attracting predators such as hedgehogs, birds, or frogs by adding wildlife garden ideas to your space. If you use diatomaceous earth, use food-grade diatomaceous earth, which is available from Amazon.
Pest and disease monitoring should also be viewed as an essential part of how to keep dahlias thriving. Not only are they able to destroy the aesthetics of the flowers, but they may also cause trouble for the buds, causing them to grow in a distorted manner or not to open at all. Preventing them from attacking or dealing with any outbreaks quickly will ensure your plants have a stunning display of colorful dahlia blooms for longer.
