Geraniums are popular flowering plants that add vibrant color to gardens and patio containers. However, yellowing leaves on geraniums can be unsightly and indicate underlying issues. Understanding the most common reasons for yellow geranium leaves can help you pinpoint the cause and get your plants back to health.
Overwatering
One of the most frequent causes of yellowing geranium leaves is overwatering. Geraniums prefer soil that drains well and does not stay soggy. Excess moisture around the roots can cause yellow leaves, drooping, and eventual root rot.
To avoid overwatering, allow the top inch or two of soil to dry out between waterings. Check by sticking your finger in the soil to gauge moisture. Reduce watering if the soil stays wet for extended periods. Yellow lower leaves that eventually turn brown and fall off are typical signs of overwatering.
Underwatering
While geraniums don’t appreciate soggy soil, letting them dry out too much can also cause yellowing leaves. If you allow the soil to become completely parched between waterings, the plants respond with yellow lower leaves, wilting, and stunted growth.
Check the soil before watering and water thoroughly until it runs from the drainage holes. If the leaves perk up after watering, you left the plant too dry. Increase frequency to keep the soil evenly moist but not drenched.
Low Humidity
Geraniums prefer average to high humidity levels around 40-50%. When humidity drops below 30%, you may notice yellowing, browning, or curling leaves. This occurs because low moisture levels cause the leaves to lose water faster than the roots can absorb it.
Boost humidity for geraniums by grouping plants together, setting pots on pebble trays, or misting plants daily. Avoid drafty spots and direct air vents that contribute to excessively dry air around the plants.
Insufficient Light
Although geraniums can tolerate partial shade, insufficient light often causes lower leaves to turn yellow. If the plants receive less than 4-6 hours of direct sun daily, they expend more energy than they can produce through photosynthesis.
Boost light by moving pots into a sunny window or location outdoors that receives direct sunlight for much of the day. Dappled shade under a tree is usually not enough for geraniums to thrive. Once given adequate sunlight, the plants will stop dropping lower leaves.
Cool Temperatures
Geraniums grow best in warmer daytime temperatures around 70-80°F (21-27°C). If nights become cooler than 55°F (13°C), the plants may react by turning leaves yellow. Prolonged exposure to cool temps can also cause stunted growth.
Protect geraniums from chilling if cooler weather arrives by moving them to a sunny indoor location. Avoid drafty windows or allowing plants to touch cold window panes. Indoors, keep pots above heated surfaces that may dry out the roots.
Nutrient Deficiencies
Lack of nutrients can also cause geranium leaves to turn yellow. Nitrogen deficiency typically affects the lower leaves first. Without enough nitrogen for chlorophyll production, the lower leaves turn yellow or pale green and eventually drop.
Prevent nitrogen deficiency by fertilizing geraniums every 2-4 weeks during the growing season with a balanced liquid fertilizer. If yellowing persists, try a fertilizer higher in nitrogen. Iron deficiency shows as yellowing between leaf veins while veins remain green. Apply chelated iron if iron deficiency is suspected.
Root Damage
Anything that damages geranium roots can disrupt the plant’s ability to take up moisture and nutrients, resulting in yellow leaves. Root damage may be due to transplant stress, dried out roots, compacted soil, pests like root aphids, or diseases like root rot.
Avoid transplant stress by gently removing plants from pots and handling roots carefully. Check that roots are silvery-white, not brown or mushy, which indicates rot. Loosen compacted soil before planting. Rule out root pests or disease and treat any issues.
Other Causes
- Older Bottom Leaves: Older lower leaves on geraniums naturally turn yellow and drop off as part of the plant’s development. As long as it’s only the lower leaves and the rest of the plant looks healthy, this is usually normal.
- Viruses: Viral infections like tomato spotted wilt virus or impatiens necrotic spot virus can cause yellowing. Look for ring spots or distorted growth. Destroy infected plants to prevent spread.
- Fungal Issues: Fungal diseases like botrytis blight or pythium can lead to yellowing leaves. Provide good airflow and avoid wetting foliage to reduce disease problems.
- Pests: Spider mites, aphids, or whiteflies can all suck plant juices and cause yellowing. Check the undersides of leaves and stems for tiny pests or sticky honeydew secreted by them. Use horticultural oils or insecticidal soaps to treat infestations.
- Chemical Sensitivity: Exposure to chemicals like herbicides or gasoline fumes can turn geranium leaves yellow. Avoid spraying weed killers near geraniums.
Key Takeaways on Yellow Geranium Leaves
- Check soil moisture and avoid both under and overwatering geraniums.
- Give geraniums at least 4-6 hours of direct sun daily.
- Protect from cool, dry air which can dehydrate leaves.
- Fertilize regularly with a balanced plant food.
- Inspect for root damage, pests, or diseases.
- Allow older bottom leaves to naturally die off.
- Avoid chemicals and weed killers around geraniums.
- Discard plants infected by viral or fungal issues.
With proper care, you can get your yellow-leaved geraniums back in top form and enjoyment. A little detective work can often pinpoint the underlying cause so corrective steps can be taken.
Frequently Asked Questions About Yellow Geranium Leaves
Why are my geranium leaves turning yellow?
The most common causes of yellowing geranium leaves are overwatering, underwatering, insufficient light, cool temperatures, low humidity, nutrient deficiencies, root damage, pests, diseases, and chemical sensitivity.
What does it mean if lower geranium leaves are yellow?
Yellow lower leaves most often indicate overwatering or lack of nitrogen. Allow soil to partially dry between waterings and fertilize with a balanced plant food to supply nitrogen. Lower leaf yellowing can also be normal aging.
How can I fix yellow geranium leaves?
Fix yellow leaves by adjusting watering practices, providing more sunlight, warming indoor temps, raising humidity, applying fertilizer, treating pests/diseases, inspecting roots, and eliminating exposure to chemicals.
Should I remove yellow geranium leaves?
It’s best to leave yellow leaves attached until they naturally fall off, which conserves the plant’s energy. However, removing a few yellowed lower leaves is okay for appearance. Avoid removing many healthy green leaves which stresses the plant.
How often should I water geraniums?
Water geraniums when the top inch or two of soil becomes dry, about 1-2 times per week in warm weather. Avoid both under and overwatering. Check soil moisture before watering to determine when plants need it.
What temperature do geraniums prefer?
Geraniums grow best with daytime temperatures of 70-80°F (21-27°C) and nights above 55°F (13°C). Move plants indoors if cooler weather arrives or protect from cold window panes.
How much sunlight do geraniums need?
Geraniums need 4-6 hours of direct sun daily. A window facing south, east or west or a spot that receives sun most of the day should provide sufficient light. Shade under a tree is usually inadequate.
How often should I fertilize geraniums?
Fertilize container geraniums every 2-4 weeks during spring through fall with a balanced liquid plant food. Slow release pellet fertilizers applied at planting time can supplement regular feedings.
What causes root rot in geraniums?
Excess moisture is the primary cause of root rot in geraniums. Allow soil to partially dry between waterings, provide drainage holes, remove excess water from trays, and avoid planting in heavy, poorly draining soil.
Conclusion
Yellowing leaves on geraniums commonly result from cultural issues like improper watering, light, temperature, or humidity. Nutrient deficiencies, pests, diseases, and root damage can also cause leaves to turn yellow. By understanding the most likely reasons for yellow geranium foliage, you can diagnose and correct problems for healthy, vibrant plants. With a few adjustments to care, your geraniums can regain their colorful blooms and attractive leaves.