Marigolds are a popular flower amongst home gardeners. They are low-maintenance, and provide beautiful blooms for long periods. Grown as an annual, Marigolds do best in warm climates and are quite tough. Although they are quite tough and able to withstand numerous conditions, they aren’t immune to some common plant issues.
Things that are out of our control such as too much rain, bug infestations, or hungry deer are a few things that can harm your marigolds. So what can you do once you see issues start to pop up?
The first step is actually identifying the problem. Once you’ve identified what’s going on with your plant, you can put a plan of action together that will help bring your marigolds back to a happy, healthy state. Let’s take a deeper look at some of the most common marigold problems, and how to fix them!
Wilted leaves can be caused by a few things. The most common reason leaves wilt is that the soil is too dry. If this occurs, increase your watering frequency. It can be tempting to keep your plants moist after seeing wilted leaves, but don’t!
Once they perk back up, simply maintain a consistent and frequent watering schedule. If you keep your plants too moist, especially marigolds that don’t like to be kept moist, you can stress your plant out further.
Plants will also show signs of wilting when they are experiencing heat stress. This usually occurs in the warmer summer months and has almost nothing to do with moisture. Heat stress occurs when the temperatures remain high and the plant cannot use the water in the soil fast enough to cool themselves off.
It can be tempting to water your plants if heat stress happens, but it is important to stick to your regular watering. Soaking heat stressed plants can deprive the root system of oxygen and will further stress your plants out.
A tell tale sign between wilting from being dry and wilting from heat stress or overwatering is the color of the foliage. A plant that is too dry will look faded in color and sometimes appear brown or crispy. A plant that is overwatering or heat-stressed will still have normal dark green foliage.
Tips of leaves begin to turn dark brown when the plant has been overwatered. It usually appears on the tips of leaves but can also affect stems. Whole leaves can begin to turn brown and get crispy, eventually falling off.
Remove the affected leaves and allow your plant to slightly dry out before watering again. Once the plant has begun to dry out, return to a consistent watering schedule. Marigolds do not like to be kept too moist, so keep this in mind when watering your plants.
As an avid gardener, I was disappointed to find worms munching on the leaves and flowers of my beautiful African marigolds this season These pesky pests can quickly damage and deform the flowers, leaving them unattractive Through trial and error, I learned some effective organic methods to get rid of worms in African marigolds and restore the plants’ health.
Identifying the Worms
The main worms that attack African marigolds are caterpillars of the beet armyworm, corn earworm, and various loopers. These smooth-bodied worms blend in with foliage and can be hard to spot at first Look for dark green caterpillars up to 1-inch long with a pale stripe along the back They chew irregular holes in leaves and petals. Heavy infestations will completely skeletonize flowers and leaves.
Removing Worms by Hand
Manually picking worms off plants is an easy organic control. Inspect plants carefully, at least twice a week. Remove any worms you find and drop them into a bucket of soapy water to kill them. Pay special attention to flower buds and new growth which are favorite feeding sites.
Handpicking is most practical for a few potted plants. It gets tedious in large gardens with expansions infestations. But it’s still helpful to handpick as part of an integrated treatment plan.
Knocking Off Worms With Water
A forceful spray of water can dislodge worms from plants. Focus on the undersides of leaves and inside flower buds where worms hide. A daily blast with the garden hose works better than occasional deep watering.
For potted plants, take them to a sink to thoroughly drench and agitate the foliage. The worms will fall off and can be crushed or flushed down the drain.
Applying Organic Worm Sprays
When handpicking and hosing aren’t cutting it, organic worm spray solutions can safely eradicate infestations on contact.
Insecticidal soap – Highly effective against soft-bodied insects. Spray every 5-7 days.
Neem oil – Made from the neem tree. Smothers and poisons worms.
Bt (Bacillus thuringiensis) – A bacterial toxin that kills caterpillars when ingested.
Spinosad – Made from a soil microbe. Causes worms to stop feeding within hours.
Always follow label application instructions for these organic pesticides. Achieving full coverage of undersides of leaves and flowers is key. Reapply after rain.
Trapping Worms With Pheromones
Worm pheromone traps draw in male moths, preventing them from breeding and reducing next season’s population. Place traps near plants in spring and replace lures every 4-6 weeks.
Encouraging Natural Predators
Ladybugs, birds, parasitic wasps, and other beneficial insects feed on plant-eating worms. Avoid pesticides that may harm these predators. Plant nectar-rich flowers to attract them to your garden.
Improving Soil Health
Worm infestations often flare up when marigold plants are under stress. Boost soil fertility with compost and mulch. Water carefully and ensure pots have adequate drainage. Healthy marigolds can better withstand and outgrow pest damage.
Excluding Worms With Row Covers
Floating row covers are a physical barrier that keeps out moth eggs and larvae while allowing air, light, and irrigation through. Drape the fabric over plants and secure the edges with stones, boards, or landscape pins. For best results, install covers at planting time before pests arrive.
Inter-Planting With Worm-Repellent Herbs
Herbs like basil, thyme, marigold, garlic, and chives repel certain caterpillars through their strong scents. Inter-plant these throughout the garden, or pot small containers nearby.
Crushing herbs to release more oils and mulching beds with them is also effective. Just be cautious using this approach around African marigolds, as crushed marigold foliage can self-repel!
Crop Rotation
Rotating annual marigold plantings to a new bed each season helps break the cycle of re-infestation. Make sure to remove all plant debris after harvest, which may harbor overwintering worm eggs and pupae.
Sanitation and Weed Control
Since worms and moths thrive on weeds and decomposing vegetation, keeping the garden tidy limits their habitat. Promptly remove any discarded flowers, leaves, or dead plants. Pull weeds before they flower and set seed.
Timing Plantings Carefully
In areas with severe worm pressure, avoid spring plantings which are most vulnerable to attack. Mid-summer plantings will flower during fall when pest levels drop. Or choose faster-blooming worm-resistant varieties.
Protecting Plants With a Barrier
For prized potted marigolds, create a physical barrier with floating row cover or cutworm collars wrapped around each stem. Use care not to tear the delicate petals when adding or removing covers.
Seeking Out Worm-Resistant Varieties
Some marigold varieties have been selectively bred to be more pest tolerant. African marigolds tend to be more resistant than French options. Seek out tough, heirloom types marketed for their constitution.
Maintaining Vigilance
Be proactive and keep monitoring for signs of worms even after treatment. Catching infestations early before they explode makes eradication much easier. Be prepared to reapply organic treatments to ensure all life stages are eliminated.
Floppy Stems or Leaves
The most common reason plants become floppy or lose their turgidity is from overwatering. Plants that are not allowed to dry out in between waterings can become waterlogged causing the stems to appear limp and sometimes lean or fall over.
These floppy stems can hinder the plant from taking up moisture and nutrients properly. Most plants will bounce back from this if given time to adjust. Allow your marigolds to dry out in between waterings to prevent overwatering.
Plants that are not producing flowers usually means they aren’t getting enough sunlight. Marigolds are full sun plants and will take all the sunlight they can get. If your plants are getting too much shade due to location or surrounding plants or trees, this can hinder them from flowering. If your plants are receiving too much shade, move them to a sunnier location.
If your plants are receiving a good amount of sun, but still aren’t flowering, consider deadheading the old blooms. This can promote new growth and will help the plant produce new flowers.
Young plants will not flower until they reach a certain maturity. If you transplant young plants, give them some time to adjust to their new area and mature. If planted in the right conditions, they should flower in no time!
Plant leaves turn purple for a couple of reasons. The leading cause is usually a phosphorous deficiency. Marigolds are not super needy when it comes to fertilizer or nutrients, but depending on the soil and other surrounding factors, they can require more phosphorus.
Low night temperatures can also cause leaves to turn purple. If temperatures dip below 55, your plants can react in many ways. One way is that the leaves will start to turn purple.
If you suspect phosphorus deficiency, apply a fertilizer to your plants. A low grade all purpose should do the trick if you haven’t fertilized recently or at all. If you have been fertilizing your plants, maybe switch to another fertilizer or find one that provides a good amount of phosphorus.
Leaves turning yellow can be caused by a few different things. Lack of nutrients could be one reason your marigold leaves are turning yellow. Applying a fertilizer will help the coloration go back to normal.
Leaves can also turn yellow due to a disease called Aster Yellows. Aster Yellows affect plants in the Asteraceae family, and cause stunted growth, yellow leaves, and can affect buds and blooms.
This disease is spread by insects that can be found on your plants or weeds surrounding the area. Keep the planting area weed free and keep an eye out for insects all season.
Marigolds do not like to be kept in moist conditions. Allowing your plant to dry out in between waterings can help prevent certain problems from arising such as stem and root rot.
If your plant’s stems are turning brown, this can be a sign they are rotting. Oftentimes the rot starts in the root system where too much moisture is being held and will work its way up the plant affecting the main stem first and so on.
Applying a fungicide can help stop this from destroying your plants, but if the problem has already affected a decent amount of the plant, it might be too late. Make sure you’re planting in fresh, healthy soil to help prevent this problem from occurring.
Brown Spots or Leaf Tips
Brown spots can be caused by bacterial leaf spot, or an excessive amount of iron. Marigolds do not grow well in soils that have low pH, and this can lead to iron toxicity. A soil test can help determine if you have a low soil pH.
If the spots seem more sporadically located, they are likely caused by bacterial leaf spot. Treat leaf spot with a fungicide.
Plants become leggy when they aren’t getting enough sunlight. Marigolds grow best in areas that receive full sun, as much as they can get. If your plants are in an area that is receiving too much shade or just not enough sunlight, the plant will become leggy and look stretched out as it is reaching for more light.
Be sure to rotate containerized plants to ensure they receive even sunlight. Transplant-shaded plants into a new sunnier location and they will soon adjust to normal growing patterns.
In conditions where humidity is high, or plant leaves aren’t allowed to dry out and get good airflow, Powdery Mildew can form. Powdery Mildew is a fungus that appears as a sticky white substance on the tops of leaves.
It often occurs on older growth where leaves are more bushy and close together, but can affect new growth in certain conditions. It is important to eradicate this fungus as soon as possible as it can do a number on the host plant and spread to your other plants.
There are home remedies that can help prevent the spread of Powdery Mildew, but if it is severe a fungicide application might be necessary. Copper soap or fungicides with sulfur as an ingredient seem to be the most effective.
Yellow or brown speckling on leaves is usually caused by a bug infestation. Aphids or spider mites are usually the culprits on flowering annuals such as marigolds. Aphids appear as tiny green insects on the undersides and stems of plants.
They feed on foliage, creating a brown speckled appearance. Since aphids have such an extensive life cycle, it is important to treat them accordingly so they don’t get out of hand.
Spider mites are tiny white bugs that will create small webs that look similar to normal spider webs. They create a sticky substance across the plant and will feed on foliage which will create a yellow speckling on the leaves. Spider mite infestations start small but can increase quickly. Pyrethrum sprays are a good option for eradicating spider mites.
How to Control Pests & Disease for Marigolds : Grow Guru
FAQ
How do I get rid of worms eating my flowers?
How do you treat marigold flower disease?
How do I get rid of worms in my flower beds?