Sunscald is the pale, leathery patch that forms on the sun-facing side of tomatoes exposed to intense sun, usually after heavy pruning, leaf loss, or a heat wave. Green fruit is most at risk. Answer a few questions to see your risk and how to protect the fruit.
Try a preset:
Your entries stay in your browser. Nothing is sent to a server or saved to an account.
What Your Result Means: higher risk means fruit could develop a pale, sunken patch on the sun side. Sunscald is a physical injury, not a disease, so the fruit is safe but the damaged part should be cut away. Shade and leaf cover are the fixes.
Will My Tomatoes Get Sunscald?
It depends on how exposed the fruit is, how hot and bright it has been, and whether the fruit is green. Answer the three questions and the tool rates your risk and gives the fixes that protect the fruit.
- Choose the Exposure, shaded by leaves, or exposed after pruning or leaf loss.
- Choose the Heat, since intense sun above 90°F drives sunscald.
- Pick the Stage, as green and ripening fruit scald more easily than ripe.
What Each Result Means
| Result | What It Tells You |
|---|---|
| Risk level | How likely fruit is to scald |
| Prevention | The steps that protect it most |
| Note | That it is sun injury, not a disease |
What Raises the Risk
The main drivers of sunscald and how to lower each.
| Driver | Raises Risk | Lowers Risk |
|---|---|---|
| Exposure | Fruit bare after heavy pruning or leaf loss | Keep a leafy canopy over the fruit |
| Heat and sun | Intense sun above 90°F | Shade cloth during heat waves |
| Fruit stage | Green, ripening fruit | Fruit shaded until it colors up |
How Does the Check Work?
Sunscald happens when the sun heats an exposed patch of fruit skin enough to kill the tissue. The tool scores exposure, heat, and stage, then returns the fixes that shade and protect the fruit.
A healthy leaf canopy is the natural defense, so anything that strips leaves (over-pruning, disease, or pests) raises the risk, especially in a heat wave.
Worked Example
Say you pruned heavily, a heat wave above 90°F set in, and the fruit is still green. All three point the same way, so the tool reports a high risk and suggests easing off pruning, adding shade cloth, and letting the canopy fill in. Fruit well shaded by leaves in mild weather reads low risk.
Factors That Change the Risk
- Leaf cover: the top defense; a full canopy shades fruit from direct sun.
- Pruning: heavy pruning or leaf removal exposes fruit and raises risk.
- Heat and light: intense sun above 90°F does the damage.
- Disease and pests: leaf loss from blight or pests suddenly exposes fruit.
- Fruit stage: green fruit scalds more easily than ripe, colored fruit.
Understanding Your Outputs
| Output | Meaning | Best Used For |
|---|---|---|
| Risk level | Low, moderate, or high | Deciding whether to shade |
| Prevention | Targeted fixes | Protecting the fruit |
| Note | It is sun injury | Using scalded fruit |
When to Use It
Use it before pruning in summer, ahead of a heat wave, or when leaves are thinning from disease. Pair it with the shade cloth calculator and the pruning guide to keep enough leaf cover.
Common Mistakes to Avoid
- Over-pruning in heat: stripping leaves exposes fruit right when it needs shade.
- Ignoring a heat wave: add temporary shade cloth when sun is intense above 90°F.
- Removing too many leaves to ripen: tomatoes ripen from warmth, not direct sun, so keep the canopy.
- Letting disease strip leaves: treat blight and pests early to keep fruit shaded.
- Confusing it with disease: sunscald is sun injury and does not spread.
Accuracy and Limitations
This is a risk guide based on the causes of sunscald.
What It Tells You: your relative risk and the fixes most likely to help.
What It Cannot Predict: which exact fruit will scald. Leaf cover and shade during heat are the reliable preventions.
Methodology
Method: the causes of sunscald are scored and summed into a risk level, with matching preventions. Inputs Used: fruit exposure, recent heat and sun, and fruit stage. Scoring: exposed fruit adds 2; intense heat above 90°F adds 2; green or ripening fruit adds 1. Bands: 4 or more is high, 2 to 3 moderate, under 2 low. Preventions: keep a leafy canopy, prune lightly, add shade cloth in heat, and treat leaf-stripping disease early. Note: sunscald is a physical sun injury, not a disease.
Sources: Iowa State University Extension – Growing Tomatoes, The Old Farmer’s Almanac – Tomatoes, Royal Horticultural Society – Tomatoes. Last reviewed: September 26, 2026 · Reviewed by Aiza Anwar.
Frequently Asked Questions
What causes sunscald on tomatoes?
Intense sun heating an exposed patch of fruit until the tissue dies, usually after heavy pruning, leaf loss, or a heat wave. Green fruit suddenly exposed is most at risk.
How do I prevent sunscald on tomatoes?
Keep a leafy canopy over the fruit, prune lightly, add shade cloth during heat waves, and control disease and pests that strip leaves.
Can I eat tomatoes with sunscald?
Yes, if the fruit is otherwise sound. Cut away the pale, leathery patch and use the rest, as long as it has not started to rot where the skin broke.
Does sunscald spread between tomatoes?
No. Sunscald is a physical sun injury, not a disease or pest, so it does not spread. Each affected fruit was simply too exposed to the sun.
Why did pruning cause sunscald?
Removing too many leaves exposes the fruit to direct sun. Prune lightly in summer and leave enough canopy to shade the developing tomatoes.
Do tomatoes need direct sun to ripen?
No. Tomatoes ripen from warmth and the hormone ethylene, not direct sunlight on the fruit, so you can keep a shading canopy without slowing ripening.
What does sunscald look like?
A pale, whitish or yellowish patch on the sun-facing side that turns thin, papery, and sunken. It may later be invaded by mold where the skin has broken down.
Does shade cloth stop sunscald?
Largely, yes. Shade cloth of about 30 to 50 percent over plants during a heat wave cuts the intense sun that causes most sunscald while still letting them grow.
Are some tomatoes more prone to sunscald?
Varieties with sparse foliage and heavily pruned or staked plants expose more fruit, so they scald more easily than bushy, well-leafed plants.
Related Tomato Tools
Size Shade Cloth with the Shade Cloth Calculator
This tool rates sunscald risk from its causes and cannot predict which fruit will scald. Leaf cover and shade during heat are the reliable preventions. Sunscald is sun injury, not a disease, and the fruit is safe once the damaged part is removed. Spotted an error? Tell us here.