The care schedule that kept a plant happy in spring often falls short once summer heat arrives — higher temperatures speed up how fast a plant moves water from its roots to its leaves and releases it back into the air, a process called transpiration, and that faster cycle means the soil dries out sooner than it did just a month or two earlier. A plant that was fine watering every ten days in April can genuinely need it every five or six days at the peak of summer heat, and sticking to the old calendar interval instead of checking the actual soil is one of the most common seasonal care mistakes.
Check the soil, not the calendar
The fix is simple even if it means watering more often than you're used to: check soil moisture by feel every few days during a heat wave, rather than trusting whatever interval worked earlier in the year. Push a finger an inch or two into the soil — if it's dry at that depth, it's time to water, regardless of how many days it's been since the last one. Plants in smaller pots, in terracotta (which is porous and dries out faster), or in a spot that gets strong afternoon sun will need checking most frequently, since they're the ones most exposed to accelerated drying.
Signs your plant is struggling with the heat
Heat stress shows up a little differently than a simple watering problem, and it's worth knowing the signs specifically, since the fix isn't always just more water. Crispy, browned leaf edges on a plant that's otherwise been watered consistently often point to low humidity combined with heat, rather than underwatering alone — hot air holds moisture differently than cooler air, and many houseplants that tolerate normal indoor humidity struggle when a heat wave dries the air further. Sudden droop on a hot afternoon, even with moist soil, can simply be a plant temporarily wilting to reduce water loss through its leaves in extreme heat; it often perks back up once temperatures drop in the evening, and doesn't necessarily mean anything is wrong. A pale, bleached, or scorched patch on the side of a leaf facing a window is sun damage, made worse in summer when the sun's angle and intensity are both at their peak — a plant that tolerated a spot fine in winter can scorch in the same spot come summer.
Watch out for air-conditioning drafts
Air conditioning creates its own seasonal stress that's easy to overlook: a plant sitting directly in the path of a cold air-conditioning vent experiences a swing between hot ambient air and sudden cold blasts that few houseplants handle gracefully, often showing up as leaf drop or browning on the side facing the vent. Moving plants a few feet out of direct airflow, even while keeping them in the same general area of the room, usually resolves this without needing to relocate them entirely.
Should you fertilize more in summer?
Most houseplants are in active growth during summer heat, which does mean many benefit from regular feeding during this stretch — but pair increased fertilizing with increased watering, not as a substitute for it. A plant that's fertilized on schedule but allowed to dry out too much between waterings in the heat is more likely to show fertilizer burn on its roots, since there's less water in the soil to dilute the salts. If you're watering more frequently to keep up with summer heat, your existing fertilizing schedule usually doesn't need to change beyond that.
A quick heat-wave checklist
Move anything sensitive, like fiddle leaf fig, out of the most intense direct afternoon sun if it wasn't getting that exposure earlier in the year. Check soil moisture more often than your normal routine, especially for thirstier plants like peace lily, and water when it's dry rather than waiting for a fixed day. Keep anything near a vent a few feet clear of the direct airflow. And don't panic over a plant that droops on the hottest part of the day but recovers by evening — that's usually the plant coping normally, not a sign of a deeper problem. Drought-tolerant species like snake plant need the least adjustment of all and are a good reminder that not every plant in the room needs the same summer attention.