Yes, you can water tomato plants while the sun is shining. If the root zone is dry, do not leave the plant thirsty solely because it is midday. Morning is often convenient and reduces evaporation, but watering time should not override the plant’s actual need for moisture.
Water droplets are not a reason to withhold water
The claim that ordinary watering in sunshine inevitably makes droplets burn tomato leaves like magnifying glasses is not a sound gardening rule. Washington State University Extension’s watering-myth review addresses this misconception. Heat and inadequate water can still damage plants; that is different from proving that watering caused the damage.
Direct water to the soil around the roots where practical. This uses water efficiently and limits splashing and prolonged leaf wetness. It is useful disease-management practice, not evidence that every wet leaf will scorch in sunlight.
Check the soil before responding to wilt
Feel below the surface and inspect the root zone, especially in a container. A plant can wilt when too dry, but damaged roots in wet conditions can also fail to supply water. Adding more to saturated soil is not the right response.
During heat, check more frequently without automatically watering at every check. Consider recent rain, wind, pot size and whether the plant is newly transplanted. A small pot and an established garden bed do not share the same watering interval.
When morning watering helps
Watering early can prepare the root zone before the hottest part of the day and give accidentally wetted foliage time to dry. If that time is unavailable, irrigate when needed. Avoid making a late-evening overhead soak the default where foliage would remain wet for a long period.
Minnesota Extension’s tomato guide covers growing and watering conditions. Use regional recommendations as a starting point, then adjust to the actual soil and weather rather than treating a weekly rainfall figure as a dose for every pot.
Apply water where roots can use it
Use a gentle flow, soaker hose or suitable drip system. Apply slowly enough for water to soak in rather than run off. Check that the root zone became moist; a short surface splash may not be enough. Keep container drainage open and avoid leaving roots submerged in a filled saucer.
A timer cannot detect every blocked emitter or unusual hot spell. Inspect the plants and soil regularly. Consistent suitable moisture is more useful than alternating severe drying with large rescue soakings.
If the plant still looks damaged
Look for continuing wilt, leaf spots, root problems or fruit damage and record recent conditions. Sunscald on exposed fruit, disease and drought are different problems. Do not diagnose all brown tissue as damage from water droplets.
Keep suitable support and healthy foliage, and seek a local diagnosis for persistent symptoms. Do not add dish detergent or fertilizer to irrigation as an improvised cure. Water the roots when they need it, then investigate problems that remain.