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.
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.
Signs of scorched plants include leaf edges that are white or brown and crispy such as those on the hostas below. Other signs of plant stress, such as wilting or leaf curling on tomatoes, may also be present.
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.
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.
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!).
The time needed to recover from stress is proportional to the severity of the damage. Plant heat stress recovery may take months for crops that have been ignored for too long during a heatwave; in extreme cases, it may be impossible to bring them back to life.
Symptoms and Diagnosis
Browning of leaf margins and/or yellowing or darkening of the areas between the main leaf veins are symptoms of leaf scorch.
The Baking Soda & Water Method
If you have a scorched pan with burnt food, you can use baking soda and water to get the job done. Remove as much food and debris from the pan as possible. Make a paste of 3 parts baking soda to 1 part water. Make enough to cover the scorched portion of the pan.
Look out for white spots or dry brown splotches in random areas of a leaf. This is a clear indicator of sunburn. Sadly, the leaf won't repair itself but you can trim the areas or the entire leaf off, and there's no reason why your plant should continue suffering or not recover from its sunburn.
One of the first signs will be wilting. As the heat begins to evaporate large amounts of moisture, your plants won't be able to actively replace all the lost water, and they'll end up with droopy, sad-looking foliage. Other plants will also “close” their leaves to reduce moisture loss.
Stunted slow growth with yellowing leaves is a symptom of over-watering. Plants may suffer from leaf scorch or leaf burn. Water-soaked spots and blisters (Oedema) may appear on stems and leaves. The crown of the plant may rot.
Leaf scorch is a common symptom of transplant shock. Leaf scorch first appears as a yellowing or bronzing of tissue between the veins or along the margins of leaves of deciduous plants (those that lose their leaves in winter). Later, the discolored tissue dries out and turns brown.
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.
To scorch is to burn something fiercely, to the point where its surface — your face, prairie grass, a steak on the grill — chars or otherwise changes color. Although scorch usually refers to burning something (whether it's the sun or a blowtorch doing the burning), that's not always the case.
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.
As sad as it is, brown tips are dead tips. You can't revive dead leaf cells, but you can make corrections and save the rest of your plant.
Occasionally, leaf scorch is caused by a bacterial disease that can result in permanent damage or death to your tree.
You will want to trim the dead or scorched foliage after properly watering. Your plant is expending energy on attempting to keep the burnt parts alive. Clip these areas off so that the energy it produces will go to the areas of the plant that are still healthy.
When temperatures are exceptionally high and prolonged, plants can lose water through evaporation much faster than the roots can absorb it. Wilted, drooping leaves, resulting from a combination of excess water loss and high internal temperatures, are often the first signs of heat stress.
Damaged leaves will not recover. Prune off damaged leaves and move the plant to a shadier place, or cover it with shade netting. Use fertilisers high in nitrogen to encourage the plant to replace the lost leaves. Prevention is always better than cure.