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.
With their bright golden blooms, African marigolds (Tagetes erecta) are beloved warm-season annuals. But those cheery flowers can sometimes develop unsightly brown spots, which ruin their ornamental appeal.
Brown spots on African marigold flowers are usually a sign of disease, cultural problems, or pests. By identifying and addressing the cause, you can restore the radiant beauty of your marigolds.
Common Causes of Brown Spots
There are several possible reasons African marigold flowers may get brown blemishes:
Bacterial blight – Xanthomonas campestris pv. tagetis infects marigolds first causing water-soaked lesions on leaves that spread to flowers. Stems may also appear slimy or blackened.
Fungal diseases – Leaf spot fungus and other fungal pathogens can move from foliage to flowers, resulting in small brown lesions. Powdery mildew also causes discolored blotching.
Viral infections – Viruses transmitted by insects like thrips, aphids, and whiteflies can trigger browning flowers. Marigold mottle virus is a common culprit.
Water stress – Too much or too little water leads to brown spots on African marigold blooms. Overwatering increases disease risk while underwatering causes direct damage.
Sunscald – Flowers exposed to intense afternoon sun may develop brown dried lesions on petals.
Pests – Insects such as thrips, mites, and aphids feed on flowers, leaving behind brown blemishes and distortion.
Nutrient deficiencies – Lack of nutrients like nitrogen, phosphorus, or iron can impair marigold health, causing flower problems.
Chemical damage – Pesticides or liquid fertilizers splashing on open blooms can burn, brown, and dry out the delicate petals.
Pinpointing the underlying issue is important for proper correction. Inspect all plant parts closely and consider when symptoms first appeared.
Preventing Diseases and Disorders
While some causes of brown spots are unavoidable, good cultural care reduces risks substantially. Here are tips to grow healthy, vibrant African marigolds:
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Choose disease-resistant marigold varieties like the ‘Inca’, ‘Disco’, and ‘Zenith’ series
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Start with high-quality seeds or transplants from reputable sources
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Disinfect tools and gloves regularly with diluted bleach
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Rotate planting sites to prevent disease buildup
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Space plants adequately and avoid overcrowding
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Water early in the day, keeping foliage dry
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Apply balanced fertilizer according to soil test results
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Scout regularly for pests and treat promptly if found
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Remove spent flowers and overmature foliage
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Prune or stake plants for ample airflow
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Avoid overhead watering and control weeds
With good practices, you can avoid common problems that lead to unsightly spots on those gorgeous golden blooms.
Managing Key Causes of Brown Spots
If brown lesions do show up on your African marigolds, take action promptly to resolve the issue:
Bacterial Blight
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Remove and destroy severely infected plants immediately.
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Apply copper fungicide sprays after pruning or deadheading to protect healthy tissue.
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Space plants further apart and avoid working amid wet plants to limit spread.
Fungal Diseases
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Apply fungicides containing mancozeb, myclobutanil, or chlorothalonil weekly as protection.
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Remove foliage with leaf spot to prevent spread to flowers.
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Reduce overhead irrigation and improve airflow with proper spacing and pruning.
Viruses
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Control insect vectors like thrips that transmit viruses. Apply insecticidal soap or neem oil.
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Uproot any plants with viral symptoms right away. There are no cure-alls for viruses.
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Disinfect tools after pruning and destroy dead plants promptly.
Water Stress
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Maintain even soil moisture. Water marigolds at base only when top inch is dry.
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Reduce watering if soil stays damp. Allow deeper drying between waterings.
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Use mulch to conserve moisture and prevent wide fluctuations.
Sunscald
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Provide shade from hot afternoon sun, either through plant placement or shade structures.
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Avoid pruning or deadheading during the hottest times of day when petals are most vulnerable.
With quick identification and tailored solutions, you can resolve any causes of brown spots and protect your African marigolds. Just a bit of added care will keep those flowers fabulous!
Continued Care and Maintenance
Caring for marigolds doesn’t stop once you troubleshoot discolored blooms. Ongoing good practices limit problems and keep plants looking their best:
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Monitor plants closely for early signs of pests, disease, or stress. Address issues promptly before they intensify.
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Remove spent flowers regularly to encourage new blooms and reduce disease entry points.
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Water early in the day at soil level. Allow the top inch of soil to dry before watering again.
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Apply a balanced liquid fertilizer monthly according to product directions if needed.
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Prune leggy growth occasionally to improve form and airflow. Avoid over-pruning.
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Turn or tilt plants weekly for even sunlight exposure and upright, compact growth habit.
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Stake plants if needed to prevent flopping and keep flowers facing upward.
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Check for drained fertilizer salts accumulating in pots. Flush soil monthly to remove any buildup.
With attentive care, your colorful African marigolds will continue flowering through the season, unblemished and eye-catching. Don’t let a few brown spots detract from enjoying these warm-weather favorites.
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.
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.
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FAQ
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