Leaf Issues

Yellowing Leaves

Symptoms: Leaves turn pale green to yellow, often starting with lower leaves first. May progress to entire plant if left untreated. Common Causes:

• Overwatering leading to poor oxygen availability to roots
• Nitrogen deficiency from inadequate fertilization
• Natural aging of older leaves, especially on mature plants

Solutions:

• Reduce watering frequency and ensure proper drainage
• Apply balanced liquid fertilizer (10-10-10) every 2 weeks during growing season
• Remove yellowed lower leaves to redirect energy to healthy growth

Prevention: Maintain consistent watering schedule allowing soil to dry slightly between waterings. Feed regularly during active growth period.

Brown/Crispy Leaves

Symptoms: Leaf edges or tips turn brown and crispy, eventually spreading to entire leaf. Leaves feel dry and papery to touch. Common Causes:

• Low humidity or exposure to hot, dry air
• Fertilizer burn from over-fertilization or salt buildup
• Sunburn from intense afternoon sun exposure

Solutions:

• Increase humidity by grouping plants or using humidity trays
• Flush soil thoroughly with water to remove salt buildup
• Move to location with bright but filtered afternoon light

Prevention: Monitor fertilizer strength and frequency. Provide afternoon shade in hot climates. Maintain 40-50% humidity levels.

Drooping/Wilting

Symptoms: Leaves and stems lose turgor and droop despite moist soil. Flowers may also wilt prematurely. Common Causes:

• Root damage from overwatering or root rot
• Underwatering during hot weather
• Transplant shock or root disturbance

Solutions:

• Check soil moisture and adjust watering accordingly
• Inspect roots for rot; trim damaged roots and repot if necessary
• Provide temporary shade and maintain consistent moisture for recovery

Prevention: Use well-draining potting mix. Water deeply but allow slight drying between waterings. Handle roots gently during transplanting.

Leaf Drop

Symptoms: Leaves yellow and drop prematurely, often affecting lower leaves first but may progress upward. Common Causes:

• Sudden temperature changes or cold drafts
• Chronic overwatering or poor drainage
• Natural response to stress or environmental changes

Solutions:

• Move plant away from air conditioning vents or drafty windows
• Improve drainage by adding perlite to potting mix
• Maintain stable growing conditions and avoid sudden changes

Prevention: Keep temperatures between 65-75°F. Ensure consistent care routine. Protect from cold drafts and temperature extremes.

Growth Issues

Stunted Growth

Symptoms: Plant remains small with minimal new growth. Leaves may be smaller than normal and flowering reduced. Common Causes:

• Inadequate light levels for proper photosynthesis
• Nutrient deficiencies, particularly phosphorus
• Root-bound conditions restricting growth

Solutions:

• Move to brighter location with 6+ hours of direct light
• Apply bloom booster fertilizer (5-10-5) to encourage growth
• Repot into container 2 inches larger if roots are circling

Prevention: Provide full sun to partial shade conditions. Fertilize regularly during growing season. Repot annually in spring.

Leggy/Stretching Growth

Symptoms: Stems become elongated with large gaps between leaves. Plant appears sparse and reaches toward light source. Common Causes:

• Insufficient light causing etiolation
• High nitrogen fertilizer promoting vegetative growth
• Lack of pinching to encourage bushiness

Solutions:

• Gradually move to brighter location to avoid shock
• Switch to balanced or bloom-promoting fertilizer
• Pinch growing tips to encourage branching

Prevention: Provide adequate light from the start. Pinch young plants regularly. Use appropriate fertilizer ratios for flowering plants.

Pest Problems

Aphids

Identification: Small, soft-bodied insects in green, black, or white colors clustering on new growth and flower buds. Damage Signs: Sticky honeydew on leaves, curled or distorted new growth, yellowing leaves. Treatment:

• Spray with insecticidal soap or neem oil solution
• Remove heavily infested shoots and dispose
• Release ladybugs or lacewings for biological control Prevention: Inspect plants regularly. Avoid over-fertilizing with nitrogen. Maintain good air circulation.

Spider Mites

Identification: Tiny red or brown specks on leaf undersides. Fine webbing visible in severe infestations. Damage Signs: Stippled or speckled leaves, bronzing of foliage, leaf drop in severe cases. Treatment:

• Spray forcefully with water to dislodge mites
• Apply miticide or neem oil thoroughly to all surfaces
• Isolate infected plants to prevent spread Prevention: Maintain adequate humidity. Keep foliage clean. Inspect new plants before introducing.

Whiteflies

Identification: Small white flying insects that flutter when plant is disturbed. Eggs and nymphs on leaf undersides. Damage Signs: Yellowing leaves, sticky honeydew, sooty mold growth on honeydew. Treatment:

• Use yellow sticky traps to catch adults
• Apply insecticidal soap focusing on leaf undersides
• Vacuum flying adults early in morning when sluggish Prevention: Quarantine new plants. Use reflective mulches. Maintain healthy, vigorous plants.

Disease Issues

Botrytis (Gray Mold)

Symptoms: Gray, fuzzy mold on flowers and leaves. Affected tissues become soft and water-soaked. Causes: High humidity combined with poor air circulation. Overhead watering that keeps foliage wet. Treatment:

• Remove all affected plant parts immediately
• Improve air circulation with fans or spacing
• Apply fungicide containing copper or sulfur Prevention: Water at soil level. Space plants adequately. Remove spent flowers promptly.

Powdery Mildew

Symptoms: White, powdery coating on leaves and stems. Leaves may yellow and drop prematurely. Causes: High humidity with poor air circulation. Moderate temperatures favor development. Treatment:

• Spray with baking soda solution (1 tbsp per gallon water)
• Apply horticultural oil or sulfur-based fungicide
• Remove severely infected leaves Prevention: Ensure good air circulation. Avoid overhead watering. Choose resistant varieties when available.

Root Problems

Root Rot

Symptoms: Wilting despite moist soil, yellowing leaves, stunted growth. Foul odor from soil. Identification: Roots appear brown or black and mushy instead of white and firm. Treatment:

• Remove from pot and trim all affected roots
• Repot in fresh, sterile potting mix
• Treat with fungicide and reduce watering Prevention: Use well-draining soil mix. Never let plants sit in standing water. Ensure pots have drainage holes.

Root Bound

Symptoms: Slowed growth, quick wilting between waterings, roots visible at drainage holes. Identification: Roots circle the pot interior forming a dense mat. Soil dries out rapidly. Treatment:

• Gently tease apart circling roots
• Repot in container 2 inches larger
• Trim excessively long roots if necessary Prevention: Repot annually in spring. Choose appropriate pot sizes. Monitor root growth through drainage holes.

Environmental Stress

Temperature Shock

Symptoms: Sudden wilting, leaf drop, flower bud drop. Plant appears stressed despite proper care. Causes: Rapid temperature changes, exposure to cold drafts or hot air vents. Treatment: Move to stable temperature location. Maintain consistent 65-75°F range. Provide extra humidity during recovery. Prevention: Acclimate plants gradually to new locations. Protect from temperature extremes. Avoid placing near HVAC vents.

Humidity Issues

Low Humidity Symptoms: Crispy leaf edges, flower bud drop, increased spider mite susceptibility. High Humidity Symptoms: Fungal diseases, soft rot, reduced flowering. Solutions: Use humidity trays for dry conditions. Improve air circulation for high humidity. Maintain 40-50% relative humidity. Prevention: Monitor humidity levels. Group plants appropriately. Use fans to improve air movement.

Light Stress

Too Much Light: Bleached or scorched leaves, wilting during hottest part of day despite moist soil. Too Little Light: Leggy growth, few flowers, pale green leaves, stems reaching toward light. Solutions: Provide bright light with afternoon shade in hot climates. Supplement with grow lights if needed indoors. Prevention: Choose appropriate planting location. Use shade cloth in extreme heat. Rotate potted plants for even growth.

Quick Diagnostic Guide

Emergency Symptoms

When to Seek Help

• Plant fails to respond to treatment within 2 weeks
• Multiple problems occurring simultaneously
• Uncertain diagnosis despite troubleshooting attempts

Prevention Checklist

• [ ] Water only when top inch of soil is dry
• [ ] Provide 6+ hours of direct sunlight daily
• [ ] Fertilize every 2 weeks during growing season
• [ ] Deadhead spent flowers regularly
• [ ] Inspect weekly for pests and diseases
• [ ] Maintain good air circulation around plants

Recovery Timeline

Week 1: Remove damaged parts, adjust care conditions, begin treatment Week 2-3: New growth should appear, existing leaves stabilize, flowering may pause Month 1+: Full recovery with proper care, resume normal flowering cycle

Remember: Most Petunia problems are preventable with proper care. When in doubt, adjust watering first, then light conditions.