Mandevilla is a popular flowering vine grown for its showy trumpet-shaped blooms. However yellowing leaves are a common problem that can affect these plants. In this article, we’ll examine the reasons why mandevilla leaves turn yellow and provide solutions to restore your plant’s health.
Overwatering
The most common cause of yellowing mandevilla leaves is overwatering. Mandevillas need moist but well-drained soil. If the roots sit in soggy soil for too long, they can’t get enough oxygen. This leads to root rot, which prevents the roots from taking up water and nutrients.
To fix overwatering, remove the plant from its pot and discard any rotted or mushy roots. Repot the mandevilla in fresh, well-draining potting mix. Make sure the pot has drainage holes and use a potting mix formulated for containers, not garden soil. Only water when the top 1-2 inches of soil become dry.
You may need to trim off badly damaged leaves. Give the plant several weeks to recover in a sunny spot before resuming fertilization. Avoid location where water can collect in saucers under pots.
Underwatering
While overwatering is more common, underwatering can also cause yellow mandevilla leaves. If the soil dries out too much between waterings, the plant can’t absorb enough moisture. Leaves may turn yellow and curl or drop off.
Check the soil moisture before watering. Water thoroughly until it drains from the bottom of the pot. Make sure the plant gets at least 1-2 inches of water each week, adjusting for hotter or cooler temperatures. Add mulch to the soil surface to help retain moisture.
Nutrient Deficiencies
Lack of key nutrients can also lead to chlorosis – yellowing between the leaf veins. This happens because the plant doesn’t have what it needs to produce chlorophyll.
The main nutrients that cause chlorosis when deficient are:
- Nitrogen – Causes uniform yellowing in older leaves first.
- Iron – Yellows younger leaves while veins remain green.
- Manganese – Develops yellow spots and streaks.
- Zinc – Also causes spotted and streaked yellowing.
Use a balanced fertilizer to prevent nutrient deficiencies in mandevillas. Look for a formula made for flowering plants or tomatoes. Fertilize at half strength every 2-4 weeks in the growing season.
If symptoms persist, have your soil tested to determine which nutrients are lacking. You can then add specific amendments as needed to restore nutrients.
Pests
Sucking insects like mealybugs, aphids, and spider mites can draw out the juices from mandevilla leaves. Their feeding causes stippling, spotting, or yellowing.
Check the undersides of leaves and stem joints for clusters of small bugs. Spider mites make webs on the undersides of leaves.
Control insects by spraying the plant thoroughly with insecticidal soap or neem oil. Systemic insecticides that get taken up by the plant’s vascular system may be needed for large infestations.
Isolate and treat infected plants quickly to prevent pests from spreading. Remove badly infested leaves or stems if needed.
Diseases
Fungal and bacterial diseases can also turn mandevilla leaves yellow. Common culprits include:
- Southern blight – Caused by a soil-borne fungus. Yellowing moves up from lower leaves.
- Bacterial leaf spot – Angular yellow spots enlarge and turn brown.
- Powdery mildew – White powdery coating on leaf surfaces.
Improve airflow and avoid wetting foliage to make conditions less favorable for diseases. Remove and destroy infected leaves and stems. Use fungicides labeled for the specific disease only after accurate diagnosis.
Preventive measures like spacing plants properly can reduce disease problems. Consider resistant cultivars if diseases are a chronic issue.
Natural Leaf Aging
As part of the normal growth cycle, lower mandevilla leaves may turn yellow and drop off. This is especially common in older plants as the lower foliage ages and dies back. As long as it’s just a few bottom leaves, it’s generally nothing to worry about.
Remove yellowed leaves by pinching or cutting the petiole where it attaches to the stem. Make sure the yellowing isn’t spreading higher up on the plant, which would indicate another problem.
Light & Location Issues
Insufficient light exposure can lead to pale yellow or yellowish-green leaves. Place mandevillas in the sunniest location possible or supplement with grow lights. Moving plants outdoors for the warm season can improve light levels.
Sudden location changes, like moving a plant from indoors to outdoors, can also shock mandevillas. Give them a week or two to adjust to major light level changes before assuming another problem.
Correcting High Soil pH
If yellowing shows up in younger leaves, a soil pH issue could be the cause. Mandevillas thrive best in slightly acidic soil with a pH between 5.5-6.5. Above 7.0, they cannot take up iron and other nutrients efficiently.
Test the soil pH if iron-deficiency yellowing develops. Lower pH by mixing in acidic amendments like peat moss and pine bark. Applying chelated iron may temporarily alleviate symptoms but doesn’t fix the root cause.
By understanding the reasons behind yellow mandevilla leaves, you can take the right steps to restore your plants to vibrant green health. Pay close attention to when and where symptoms occur on the plant to accurately diagnose problems. With proper care, your mandevillas will reward you with abundant blooms.
Reasons for Yellow Mandevilla Leaves
There are a number of causes to a mandevilla plant turning yellow. Below are some of the most common reasons for yellow mandevilla leaves:
Improper watering can cause yellow leaves on a mandevilla. Too much or too little water can be reasons for yellow mandevilla leaves. Soil should remain moist, but not soggy. If roots are soggy, remove the plant from the container and remove as much of the soggy soil as possible. Repot in fresh soil that is barely moist. Waterlogged roots are a common reason for the mandevilla plant turning yellow, as is dried out soil. If the plant is getting too little water, leaves will curl as they yellow. Water if necessary. Bottom watering can be effective in this case, as the plant will only take up the water it needs.
Lack of the right fertilizer can also be responsible for yellow mandevilla leaves. If it has been a while since feeding your plant, then its likely your mandevilla plant turning yellow is due to a lack of nutrients.
If the mandevilla plant is older, some yellowing leaves are to be expected as they die to make room for new growth. A few yellow leaves on a mandevilla can be removed. When removing the yellowing leaves, take a close look at the rest of the plant, particularly on the underside of the leaves and in the axils of the leaves and stems where insects are common.
Insects can cause yellow leaves on a mandevilla. Mealybugs, spider mites, and aphids can weaken plants and are sometimes reasons for yellow mandevilla leaves. If mealybugs have taken up residence on the plant, small spots of white cotton-like material will be visible. This houses the eggs of the mealybug, where hundreds may hatch and feed on the plant. Regardless of the pest, treating yellow leaves on mandevilla is done effectively with an insecticidal soap spray or a horticultural oil such as neem oil. Large infestations may require a systemic insecticide when treating yellow leaves on mandevilla. Until you determine what is causing yellow leaves on a mandevilla, seclude it from other plants so insects or disease do not spread to healthy plants. You can then determine the problem and begin treating yellow leaves on mandevilla.
Sometimes the reasons for yellow mandevilla leaves are from disease pathogens, such as Ralstonia solancearum, the bacterial pathogen that causes Southern wilt. Plants may be fine in cool weather and when temperatures warm, pathogens may be reasons for yellow Mandevilla leaves. Plants with Southern wilt eventually die. All plant material, soil, and containers should be discarded to avoid the spread of the pathogen. Too much sun is often blamed because the gardener does not ask, “Why are mandevilla leaves turning yellow?” until temperatures have warmed, and the plant has been located in full sunlight.
Spotting Trouble: Identifying Yellow Leaves
Yellowing leaves can be as innocuous as a plant shedding its senior foliage. However, when your Mandevilla Aloha Red starts turning yellow in the prime of its life, its time to sit up and take notice.
Mandevilla (Dipladenia) sanderi – yellow, dying leaves? (Part 1/3)
FAQ
What does an overwatered Mandevilla look like?
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Greghttps://greg.appWhy Are My Mandevilla ‘Aloha Red’ Leaves Falling Over? – GregFeb 9, 2024 — The root of the problem: Identifying root rot When roots are more mushy than firm, you’ve got root rot. It’s a silent scream for help from below the …
How often should you water Mandevilla?
- General Rule: Water once a week, especially during the growing season.
- Checking for Need: Check the top inch of soil. If it feels dry, it’s time to water.
- Watering Technique: Water thoroughly, allowing water to drain out of the pot or soaker hose, but not standing in the pot.
- Hot Weather: Increase watering frequency to every other day or even daily during hot, dry spells.
- Overwatering: Avoid overwatering, as mandevillas prefer drier soil and can be susceptible to root rot.
- Indoor Watering: Mandevillas generally need less water indoors during the winter, as growth slows and there’s less evaporation.
How do you fix an overwatered Mandevilla?
The solution:
Try to remove the excess water. Make sure your pot has drainage holes at the bottom. We don’t recommend a pot with a saucer, as this can prevent the water from draining away freely. Add a layer of hydrogranules to the pot to prevent the roots from coming into direct contact with water.