Plant Sunburn: How to Spot, Prevent & Heal Sun-Damaged Plants This Summer
Even in our famously unpredictable climate, summer sunshine can bring unexpected challenges to the garden. One of the most common - and often misunderstood - is plant sunburn. Yes, plants can burn just like we can, especially during heatwaves, cloudless days, or sudden warm spells. Sunburn, also known as leaf scorch, occurs when a plant receives more sunlight and heat than it can handle, particularly when combined with dry soil and low humidity.
From young vegetables to shade-loving ornamentals, a wide range of plants are at risk. With a bit of expert knowledge, you can recognise the signs, take preventive steps, and support recovery without overreacting.
How to Recognise Plant Sunburn
Sunburned plants typically show visible stress on leaves that get the most sunlight. Look out for:
- White, pale yellow or bleached patches – these suggest chlorophyll has broken down under intense UV.
- Brown, papery edges or tips – classic symptoms of leaf scorch.
- Crispy, shrivelled foliage – leaves may curl and fail to perk up even after watering.
- Sudden leaf drop – especially after a heatwave or long dry spell.
These symptoms often appear quickly during hot weather, especially on upper, outer or south-facing foliage. If left untreated, damage can spread or leave plants vulnerable to pests.
Which Plants Are Most at Risk?
The likelihood of sunburn varies by plant type, garden placement, and recent weather changes. Commonly affected groups include:
Shade-Loving Shrubs
Delicate plants like Japanese maples, hydrangeas, and camellias are prone to burning in full midday sun. Their leaves may turn brown at the edges and curl inward.
Young or Recently Transplanted Plants
Still developing root systems can't always keep up with water demand. Without adequate hydration, these plants quickly show signs of scorch.
Container Plants
Pots heat up fast and dry out quickly. Even sun-tolerant species like tomatoes, geraniums, and salvias may suffer in containers if not well managed.
Edible Crops
Tender greens such as lettuce, spinach, and courgettes are susceptible to leaf burn. Fruits like tomatoes and peppers can develop sunscald—white, leathery patches on exposed produce.
Indoor Plants Moved Outdoors
Houseplants like ferns, peace lilies, and pothos may scorch if suddenly placed in bright sun without gradual adjustment.
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Why Plants Get Sunburned
Understanding the causes of plant sunburn helps you prevent it more effectively:
Dehydration
Sunshine increases transpiration (water loss through leaves). If roots can’t replace it fast enough, tissues dry out.
Sudden UV Exposure
Plants moved abruptly from shade to full sun don’t have time to adapt their leaf chemistry to brighter conditions.
Root Zone Heat
Dark pots and paving absorb heat, warming soil and stressing roots—especially for container plants.
Foliage Loss
Thinning leaves through pruning or pest damage can expose inner leaves or fruit to sunlight they’re not used to.
How to Prevent Plant Sunburn
Water Deeply and Consistently
Aim to water in the early morning so roots can hydrate before peak sun. Deep watering encourages robust root systems.
Apply Mulch
Organic mulch like bark, straw, or compost locks in moisture and keeps roots cool.
Create Shade
Use temporary shade structures like garden fleece, bamboo screens, or even parasols to protect vulnerable plants during heatwaves.
Harden Off Gradually
When moving plants outdoors or into brighter areas, do it slowly over 7–14 days. This helps leaves adapt and reduces the risk of shock.
Match Plant to Position
Group plants by light preference. Use walls, hedges or other structures to create natural microclimates in your garden.
How to Help Sun-Damaged Plants Recover
Prune Damaged Leaves Carefully
Remove scorched or dead leaves, but avoid cutting too much at once. Keep some leaf cover to protect stems and aid photosynthesis.
Maintain Moisture
Keep soil evenly moist (but not soggy) while plants recover. Water at the base to avoid further stress on leaves.
Provide Temporary Shade
Move pots or use temporary screens to give plants a break from the sun for a few days.
Avoid Overfeeding
Hold off on fertilisers until you see signs of recovery. Once new growth appears, feed with a balanced, gentle formula.
Be Patient and Observe
Don’t rush to replace a sunburned plant - many bounce back given time. Monitor growth, maintain good hydration, and allow for gradual recovery.
Plant sunburn is increasingly common in modern gardens, but it’s not a death sentence. With a better understanding of how and why it happens, you can take steps to prevent it and support your plants through recovery.
As summers become warmer and drier, building resilience into your garden is essential. Choose the right plants for the right spots, keep an eye on the forecast, and be ready to step in with shade and water when needed.
