The good news is that yes, your plant can recover from sunburn if it's not too bad. The bad news is that the sunburnt parts of the plant will never go away; it'll always have a scar if it does pull through.
Keep them in a shady spot to give them a chance to recover: even plants that look terminally crispy can often revive and re-sprout with this treatment. Larger pots should be heavily watered, then allowed to drain – one deep watering is better than daily sprinkles.
If the sunburn is not too severe, the plant can recover by growing new tissue to replace the damaged tissue. The plant may also produce new pigments to protect against further damage. However, if the sunburn is severe, the plant may not be able to recover, and it may die.
Once leaf scorch has occurred, there is no cure. The dehydrated portions of the leaf will not turn green again, but with proper water management, the plant may recover. Prevention of scorch needs to begin with winter watering.
What can you do? Once leaf scorch has occurred, there is no cure. The leaves that have already turned brown will not recover, BUT as long as you water properly, the rest of the plant should survive. Deep watering is recommended – a slow, deep soaking of the soil at the roots.
Potted plants that are completely dried out and crispy could either just have gotten fried by the sun's intensity or have potentially been overwatered. Sun-scorched plants can be cut back and fertilized and should recover with time (planting in the ground would be even better!).
Once the damage has happened, it's OK to remove the affected leaves, which should mostly be on the outside of the plant. Or, you can let them fall off naturally (they may be protecting leaves on the inside of the plant!) Make sure you are not watering too much or too little-do the finger test.
For plants already suffering, use a sunshade to restrict their exposure to UV light. Slowly give them more time each day with the sunshade removed until they are toughened up. This process can take about two weeks, at which time your plant should be ready for the sun.
If a small part of the leaf is burned, but the plant is still getting water and functioning, it's best to just let it be. In more severe cases where the leaves are completely brown and dry, it is best to remove them before disease takes over the rest of the plant.
Browning of leaf margins and/or yellowing or darkening of the areas between the main leaf veins are symptoms of leaf scorch. Due to environmental causes, leaves may dry, turn brown, and become brittle. Look for damage to trees and shrubs on the upper portion on the sunny, southern side, and on the windy side.
It can take anywhere from a couple of days to a couple of months for stressed plants to recover. Recovery time depends on the amount of damage that the heat caused to the plant. If a stressed plant is completely neglected during a heatwave, it can take several months or even be impossible to revive it.
Some plants died and others were fried by the record-breaking temperatures. Even some that look extremely bad, like rhododendrons and hydrangeas, can bounce back. Burned leaves don't necessarily equal a dead plant, so patience and observation is needed.
Sun sensitive plants need immediate shade after overexposure to the sun. If the plants are potted, then move them to a covered porch or indoors. If the plants are in the ground, then cover them with a fabric sun screen that is rated for landscaping. Watch the plants over the next few days to see how well they respond.
Browning leaves are typically caused by under watering, sunburn, or overwatering. If the leaf tips are turning brown and crunchy, the soil likely became too dry for too long in between waterings. This can also cause the plant to drop leaves.
While medical professionals cannot reverse the effects of sun damage entirely, there are treatments that can help with collagen production, skin turnover, improvements in the appearance of dark spots and more. These include: Topical treatments containing retinol. Chemical peels.
Once leaf tissue is scorched, the damaged areas will not recover; however, minor damage, while unsightly, will not kill the plant. Leaves with scorched margins may look unappealing, but they still help the plant with photosynthesis, creating food for new, undamaged leaves to emerge.
Scorch symptoms may differ between plant species, but it typically appears in July and August as a yellowing between leaf veins and along leaf margins, and a browning on the tips of leaves. Since these leaf parts are the last to be supplied with water from the roots, they are usually the first to be affected.
When shade-loving plants, such as hosta or impatiens, are planted in full sun, leaf scorch or sunburn can occur. Strong sun and heat cause the breakdown of chlorophyll in the leaf. Damage appears as pale, bleached or faded areas.
Leaves with slight damage can be trimmed back, especially if it's the leaf tip. If you prefer to remove the whole dying leaf, that's fine too. Trimming back dying foliage will encourage new growth. However, you also have the option to leave dead leaves on the plant as long as there's not an insect infestation.
If you did see damage to your hydrangeas, the burnt leaves themselves will not recover, but this does not mean that your plant will not survive.