Why Are My Cucumber Leaves Turning White After Transplanting?

If you’ve noticed your cucumber seedlings or transplants developing white leaves, don’t panic! There are a few common causes for this issue that can often be corrected with a few adjustments to care In this article, we’ll explore the reasons cucumber leaves may turn white and what you can do to get your plants back to their normal vibrant green

What Causes White Leaves on Cucumber Plants?

There are four main culprits that can lead to whitening of cucumber foliage

• Sunburn
• Cold injury
• Overwatering
• Powdery mildew

Sunburn

Young cucumber seedlings grown indoors or in greenhouses have thin, delicate leaves. When suddenly moved into direct outdoor sunlight, the leaves can sunburn This causes bleaching and whitening of the leaf surfaces exposed to intense UV light. The younger leaves at the top are most susceptible

Cold Damage

Cucumbers thrive in warm conditions. Prolonged exposure to temperatures below 50°F can injure plants. This cold stress often manifests first as whitened, wilted foliage. This occurs more frequently just after transplanting seedlings started indoors.

Overwatering

Excess moisture in the soil can lead to root rot and other fungal diseases. This stresses the plant, impacting its ability to move water and nutrients. As a result, the leaves turn pale green, then yellowish, and finally white.

Powdery Mildew

This common cucumber fungal disease first appears as white powdery patches on leaves. It eventually spreads, covering the entire leaf surface. High humidity and poor air circulation encourage mildew growth.

How to Treat and Prevent White Leaves on Cucumbers

Once you’ve diagnosed the cause, take these steps to get your cucumbers back to normal:

For Sunburned Leaves:

• Move plants back to partial shade or use shade cloth to filter sunlight.
• Gradually expose to more sun over 7-10 days to harden off.
• Mist leaves daily to cool and provide protection.
• Avoid transplanting during intense afternoon sun.

For Cold Damage:

• Cover plants overnight if frost is predicted.
• Warm soil to at least 65°F before planting.
• Use row cover or cloches if night temps are cool.
• Don’t transplant too early in cool climates.

For Overwatering:

• Allow soil to dry out between waterings.
• Check drainage and amend soil if too compacted.
• Reduce watering frequency and amount.
• Allow unplanted transplants to dry slightly before setting out.

For Powdery Mildew:

• Improve air circulation with spacing and pruning.
• Water at the base of plants instead of from overhead.
• Apply neem oil or sulfur sprays preventatively.
• Use resistant varieties like Marketmore 76.

How to Prevent White Leaves When Transplanting Cucumbers

You can avoid many issues by using proper care when transplanting:

• Harden off seedlings slowly over 7-10 days before transplanting.

• Transplant on an overcast day or late afternoon to avoid sun intensity.

• Bury leggy stems to establish more roots but keep true leaves above soil.

• Water transplants thoroughly and provide shade for a few days.

• Let soil dry slightly before transplanting to avoid staying too wet.

• Space plants appropriately to allow air circulation.

• Provide wind protection if exposure is very high.

• Warm soil to at least 60 ̊F before planting tender vegetables.

• Cover at night if frost is expected using fabric row covers.

• Mulch around bases to retain soil warmth and moisture.

What to Do for White Cucumber Leaves

If you catch the issue early, there’s a good chance you can still save your plants:

• Prune off the whitest, most damaged leaves to stimulate new growth.

• Move to ideal growing conditions with warmth, sunlight, and airflow.

• Feed with a balanced fertilizer to promote recovery.

• Be sure to keep soil evenly moist but not waterlogged.

• Monitor for signs of disease like powdery mildew and treat if found.

• Protect tender growth from direct sun, wind, and cold until stronger.

• If damage is severe, replant with a new healthy seedling.

• Whitened leaves won’t recover but new ones will grow normally.

How to Prevent Issues When Starting Cucumber Seeds

You can avoid many transplant issues by using proper care when starting seeds:

• Sow seeds in peat pots to minimize transplant shock.

• Use grow lights to prevent leggy, spindly seedlings.

• Allow the top inch of soil to dry between waterings.

• Ensure indoor temps stay between 65-75 ̊F for robust growth.

• Harden off before transplanting outside in stages over 7-10 days.

• Transplant on an overcast, calm day to avoid harsh conditions.

• Water in transplants well and provide shade structures as needed.

Is White Foliage Always a Problem on Cucumbers?

Not necessarily! Two varieties actually have white leaves naturally.

• White Wonder is an heirloom variety with light green and white marbled leaves.

• Suhyo Long is an Asian cucumber cultivar with attractive white foliage.

So unless you’re growing one of these, whitening leaves indicates an underlying cultural issue to address.

Troubleshooting Whitening Cucumber Leaves

Cucumbers can be tricky to start from seed and transplant successfully. But assessing your specific conditions and adjusting care accordingly can get your plants back on track. With attention to hardening off, protection from sun/wind/cold, and proper spacing and watering, your cucumber transplants and seedlings should take off and thrive!