By: Kristi Waterworth
Hollyhocks (Alcea rosea) lend an old-fashioned charm to the back of the garden border, or serve as a seasonal living fence, creating a little extra privacy through the spring and summer. Even though these plants are often extremely tough, a little hollyhock pest control will keep your bed filled with blooms for years to come.
What are Hollyhock Weevils?
Hollyhock weevils (Apion longirostre) are gray snout beetles with orange legs, measuring 1/8 to 1/4 inch (0.5 cm.) long, including their pronounced proboscis, which is significantly longer in females than males. Hollyhock weevil adults overwinter in the soil of infested hollyhock beds, emerging from hiding in spring to feed and lay their eggs. The female chews a small hole in a flower bud before inserting a single egg, repeating this process many times.
The hollyhock weevil egg doesn’t interfere with flower formation but instead becomes enveloped inside the hollyhock seed pod as it develops. Here, the larvae feed and pupate, emerging as adults and dropping into the soil from late summer to early fall. Hollyhock weevils produce just one generation a year in most locations.
Hollyhock Weevil Damage
Weevil pests on hollyhocks cause only minor visual damage, chewing small holes in hollyhock leaves and flowers. However, they can cause serious damage to the overall lifespan of hollyhock stands. Larval hollyhock weevils develop within the hollyhock seed pods, using embryonic seeds for food. When the seed pods are mature, they are often empty, preventing hollyhocks from self-seeding. Since these plants are short-lived perennials at best and may require two years to produce blooms, hollyhock weevil larvae can seriously disrupt the life cycle of your hollyhock bed.
Controlling Hollyhock Weevils
A careful watch for adults and feeding damage in the spring will clue you into the nighttime visitations of hollyhock weevils. You should examine your plants carefully after dark with a flashlight to determine the extent of your pest problem before deciding how to proceed. Often, hollyhock weevils can be handpicked from hollyhock leaves and buds and dropped into a bucket of soapy water to drown.
Safer insecticidal options are available when hollyhock weevils cling tightly to leaves or there are so many feeding on your plants that hand-picking becomes an insurmountable task. Spray insecticidal soap directly on these pests; it will kill them on contact. If caught early in the season, you may be able to prevent them from laying eggs by checking nightly, destroying the pests you find, until no more hollyhock weevils are detected.
If your hollyhock seeds couldn’t be spared from the hollyhock weevil’s efforts, you should destroy seed pods as soon as they become visible to destroy eggs, larvae, and pupae. Although this will have a serious impact on the next generation of hollyhocks, chances are good that many of the seeds would have already been consumed. In the long-run, removing one season’s seeds may save your entire stand and keep the area friendly to future hollyhock plantings.
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I have a beautiful dark red hollyhock that I want to retain by planting some of its seed. What is the right time to collect seed? Do the seeds need any special treatment prior to planting? Thank you.
I typically wait until the blooms have faded and then deadhead to collect the spent blooms. Allow these to dry and then collect the seeds. You can then store them in either a brown paper bag (in a dark location) or an airtight container for spring planting. This article should help with growing them: https://www.gardeningknowhow.com/ornamental/flowers/hollyhock/tips-on-hollyhocks-growing-hollyhocks-successfully.htm
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Plants→Alcea→Hollyhock (Alcea rosea)
|Alcea rosea subsp. ficifolia||Synonym|
|Plant Habit:||Herb/Forb |
|Life cycle:||Biennial |
|Sun Requirements:||Full Sun |
|Water Preferences:||Mesic |
|Minimum cold hardiness:||Zone 2 -45.6 °C (-50 °F) to -42.8 °C (-45°F) |
|Maximum recommended zone:||Zone 9a |
|Plant Height :||5 to 8 feet (1.5-2.4m)|
|Leaves:||Unusual foliage color |
|Flower Color:||Pink |
|Bloom Size:||3"-4" |
|Flower Time:||Summer |
Late summer or early fall
|Uses:||Will Naturalize |
Suitable as Annual
|Wildlife Attractant:||Bees |
Independence Day and the beginning of the hottest days of summer, the Dog Days, are the major events in July. Gardeners and honey bees are trying to keep cool and harvesting food.
Honey bees get nectar and pollen from this plant. Single flowered varieties are best.
Alcea rosea is a larval host plant for several butterfly species, including the Common Checkered Skipper, Painted Lady, West Coast Lady, and American Lady.
I have found that this can get a bit weedy (as in lots of seedings) but they are easily pulled if gotten to early. Heavy clay soil doesn't seem to bother it. Grown in full sun. The leaves get a bit ragged looking near the end of the season but that is due to mostly butterfly larva. Other insects include Hollyhock weevil.
For best results (if you are planting more than one), plant Alcea 1 and a half feet apart from each other.
Easy-to-Make Bug Sprays for Plants
Choose one of these solutions for a simple and natural way to get rid of unwanted bugs in the garden or for indoor plants.
Oil-Based Homemade Bug Spray for Plants
You already have what you need at home to make this bug repellent. This oil-based spray works as a way to get rid of aphids, thrips, and many other insects. When making this oil-based spray, you are making a concentrate rather than a ready-to-use solution.
Recipe for Oil-Based Homemade Bug Spray for Plants
Mix the oil with a mild soap, such as Dr. Bronners Castile soap, in a large container. To prepare for use add two teaspoons of the insecticide with 1 quart of water inside a spray bottle. Spray directly on plants that have pests.
Natural Bug Soap Spray
This insecticidal soap spray is similar to the recipe mentioned above. It does not contain oil but is just as effective as the oil-based spray.
DIY Soap Bug Spray Recipe
For the liquid soap, use a mild detergent such as Castile soap. Combine the soap and water in a spray bottle, shake well, and spray directly on the surface of the infested plants.
Soap spray should only be applied early in the morning or in the evening, and never during the hottest part of the day as it could burn the plants.
Organic gardeners love neem oil, as it is a biodegradable and nontoxic insecticide. Neem oil spray works against a variety of insect pests and is considered a natural fungicide.
Neem Oil Bug Spray
Combine Neem oil with water and soap in a spray bottle. Shake to mix and spray directly on affected plants. Neem oil can also be used as a preventive on houseplants not yet infested.
Natural Bug Spray for Garden
Although you might enjoy the aroma of garlic, not everybody does, including insects. Garlic’s strong smell is what makes it such an effective natural insect repellent.
Natural Bug Spray for Garden Recipe
- 2 heads of garlic
- 1 quart of water
- ½ cup of vegetable oil
- 1 teaspoon mild soap
Puree the garlic and water in a food processor or a blender and allow to sit overnight. Strain mixture into a jar, and then add vegetable oil, soap, and more water. To use, dilute 1 cup garlic mixture with 1 quart of water inside a spray bottle and spray on infested plants.
If you are looking for something safe to use around vegetable plants, diatomaceous earth in food grade is an excellent choice as it’s a sedimentary rock formed from fossilized algae.
To use diatomaceous earth, sprinkle it around your garden or directly on foliage. This natural pesticide must be reapplied after it rains, as the rain washes away the powder.
Tomato Leaf Insecticide
Tomato plants contain alkaloids, as they are a part of the nightshade family. Alkaloids are beneficial for controlling pests, such as aphids and other destructive garden insects.
Tomato Leaf Bug Spray Recipe
For getting rid of aphids on tomato plants, chop the fresh tomato leaves. Add the leaves to the water and allow to sit overnight. In the morning, strain out the leaves. Pour tomato water into a spray bottle and spray on your vegetable plants to eliminate bug problems of all kinds.
Chili Pepper Plants Bug Spray
This natural insecticide spray is similar to the garlic spray above. It’s interesting to note the spray can be diluted or used full-strength on infested plants.
DIY Bug Spray for Vegetables with Chili Peppers
Puree chili peppers with one cup of water in a food processor. Pour into a pot, add a quart of water and bring to a boil. Allow the concoction to cool, strain out chilies, and pour into a sprayer. Add three drops of liquid soap directly to a sprayer and spray on plants as needed.
Garlic and Onion Based Homemade Insecticide
This recipe uses a handful of methods to create a natural pesticide that is safe and nontoxic, even when used at full-strength.
Recipe for Homemade Insecticide with Garlic and Onion
- 1 garlic bulb
- 1 onion
- 1 teaspoon cayenne pepper
- 1 tablespoon of liquid soap
Puree garlic, onion, and powdered cayenne pepper and let sit for up to one hour. Strain into a jar or spray bottle and add liquid soap. Shake or stir to mix well.
Use full strength on the upper and lower sides of leaves. Store leftovers in the refrigerator for up to one week and then toss.
Hot Pepper Spray
If you have a mite or whiteflies problem, you need to whip up a batch of hot pepper spray. The capsaicin, which is the compound that causes peppers to be hot, irritates garden pests just as it irritates humans.
Recipe for Hot Pepper Spray
Mix hot pepper sauce and dish soap in a quart of water. Allow to sit overnight and then transfer to a sprayer. Spray infested plants as needed.
Garlic Oil-Based Bug Spray for Plants
If you need something to deter Japanese beetles, as well as other beetles, mites, and whiteflies, a garlic oil spray should do the trick. Never apply garlic oil spray to plants during the heat of the day, as the oil will burn the plant leaves.
Garlic Oil Spray Recipe
Mince the garlic and add to the mineral oil. Let sit overnight and then strain to remove the garlic. Add strained oil to a pint of water and then add dish soap. Store in a glass bottle.
You must dilute the mixture before using it. To use the spray, add two tablespoons garlic oil mix to a pint of water. Spray plants generously.
Slugs are deterred in a variety of ways. One method uses beer placed in an old can or pie plate positioned in the ground. Sink the container deep into the soil and keep beer one inch below the soil levels, so the slugs have to enter the dish to drink.
Citrus rinds placed around the garden do well to trap slugs, as well as snails. Every morning check the peels for slugs and snails, throw away any infested peels and replace them with new ones.
What do earwigs eat? Earwigs are not only scary-looking, but they can eat your plants and beneficial garden bugs. No one wants an earwig infestation in a flower or vegetable garden. Trap earwigs with a wet newspaper and some string. Roll up the paper, get it wet, and tie it with a string.
Place the damp newspaper in an area known for earwigs. In the morning place wet newspaper inside a plastic bag and dispose of in the trash. Earwigs crawl into the paper and get stuck. Throw them away with ease.
Why buy a commercial yellow jacket trap when you can make your own with an empty two-liter bottle and some sugary liquid? To make the trap, cut the bottle about a quarter of the way down. Turn spout end upside down and place inside the bottom portion of the two-liter, so the spout is pointed down.
Fill the bottle with 1 cup of sugary liquid, such as juice, soda, or sugar water and add a dash of vinegar to prevent honey bees from landing in the trap. Empty the trap at night when yellow jackets are less active. Replace liquid as needed.
Natural Plant Spray with Baking Soda
Powdery mildew on your plants is just as big a concern as an insect infestation. To prevent powdery mildew in your vegetable garden use a baking soda spray.
Q. Hollyhock seeds and weevils
I've been collecting various Hollyhock seeds from the neighborhood to plant for next year's front yard border. I've been storing them in paper envelopes. When I went to add more seeds today, I noticed the weevils crawling up the side of the envelope. I've smashed as many as I could see but now I'm concerned that the seeds will be useless because obviously the weevils have laid eggs in some of them. Is there a way to fumigate the seeds to kill the eggs? Is it possible to inspect the seeds to see if they're still good? Or should I just dump the whole lot and buy the plants from the nursery?
I have heard that putting the seeds in a container (or envelope) for about a week or so will kill off the weevils. If you put them in an airtight container(glass/plastic), allow it to sit at room temp before opening. Though I personally have not tried this and can, therefore, not swear to its effectiveness, I think it would still be worth a try before dumping the seeds completely. If the seeds have already been devoured inside by the weevils, though, their viability, of course, will be zero.
It may be worth learning how to look for and treat the weevil issue on the plants by sharing the following article with your neighbors, which will reduce the chances of infected seeds: https://www.gardeningknowhow.com/ornamental/flowers/hollyhock/controlling-hollyhock-weevils.htm
An old fashioned favorite, the hollyhock, is easy to grow but the leaves are often riddled with orange spots and holes.
Rust is the cause of orange spots on leaves. Though it looks bad your plant will survive. A thorough cleanup in fall will help reduce the source of disease next season.
The hollyhock weevil eats small irregular holes in the leaves while Japanese beetles can riddle the leaves with holes eventually skeletonizing them. Knock these pests into a bucket of soapy water to reduce their population and feeding damage.
Caterpillars and sawflies can also eat irregular shaped holes in the leaves. Look for them at dusk on the underside of leaves and along the stems and remove any you find.
Healthy plants will survive these pests. Consider masking the damaged leaves with nearby shorter plants while allowing the flowers to shine through.
A bit more information: Grow Happy Lights Hollyhocks, a more rust resistant cultivar, for vibrant colored single flowers on 5 to 7 foot tall plants. Start the seeds indoors in late winter for bloom the first summer or plant in the garden midsummer for flowers the following year. Plant seeds of hollyhocks every year for yearly bloom.
Because thrips are so little, they can be difficult to see until infestations become large. So, one way to determine if thrips are infesting plants in or around your home is to put a blank sheet of white paper beneath the flowers or leaves of the plant and shake the plant. If there are thrips on the plant, at least some will fall off, and their dark bodies will be easily seen on the white paper.
By doing this, you also will be able to collect samples of the insect for identification. Whether attempting to identify the insects as thrips on the paper or simply inspecting plants for thrips, a 10- to 15-power magnifying glass will help enlarge your viewing of the thrips enough to see detail.
You also can use sticky traps to capture thrips for monitoring and identification. This will not provide control of the thrips, but it will let you know if a plant is becoming infested. It is recommended that specially made blue traps be used, rather than standard yellow traps the blue traps seem to be more effective and it is easier to see the light-colored nymphs on blue than on yellow.