Why Your Houseplants Struggle in the Heat and How to Save Them

Outside, the plant kingdom is in bloom at this time of year, but indoor houseplants are a different story. Rising heat, humidity, drastic temperature swings, and intense sunlight make caring for houseplants in the summer a challenge. Your routine for caring for ferns, ficuses, flowers, and other houseplants will need to change during the warm summer months, and a few simple adjustments will ensure that these plants thrive even during the worst heat waves.

We reached out to expert online plant retailer Sarah Doyle, who sells greenery and other goods through her digital store YayasPlantShop on a new marketplace called Palm StreetDoyle stresses that plant owners should be extra careful during the warm, humid months, when bacteria, fungi and herbivorous insects thrive.

Here are her top tips for keeping plants alive in summer.

Tackling mold and mildew

Mold can quickly destroy your plants, and nowhere does it thrive more than in the summer. “If you see mold on the soil surface, usually white in color, mix one part hydrogen peroxide with eight parts water,” Doyle says. “Put this solution in a spray bottle and mist the soil surface four to five times a day. Mold can thrive in humid environments, especially with alternating heat and air conditioning. This method will help reduce mold without harming the plant.”

Adjust your watering routine

Proper watering is the most common cause of plant death. “In the summer, houseplants need significantly less water than outdoor plants,” Doyle told me. “Air conditioning helps keep the soil moist, so be careful not to overwater and cause root rot.

Water less frequently in the summer and use the fingertip test to make sure the top inch of soil feels dry before watering again. To avoid overwatering, double the time between your usual watering schedule. The best time to water is early morning or late evening to minimize water loss through evaporation.

Sunlight management

Doyle recommends keeping an eye on how much sun plants are getting in the summer, too. “Use sheer curtains to diffuse intense sunlight so leaves don’t burn, and rotate plants every few days to ensure even light distribution. Watch for signs of excessive light, such as yellowing or browning leaves, and adjust placement as needed. Seasonal changes may require repositioning, and UV-blocking window films can help reduce light intensity.

Succulents and cacti do well in south- or west-facing windows, while ferns and philodendrons prefer indirect light from east- or north-facing windows. These strategies will keep your houseplants healthy and vibrant throughout the summer.

Fertilize regularly

Summer is a major growing season for many houseplants, so it’s a great time to fertilize. Apply a balanced, water-soluble fertilizer every two to four weeks to provide essential nutrients. Some of the best indoor fertilizers include: Wonder-Gro, I am a ghost And Back to the roots. Be careful not to over-fertilize, as this can be harmful to the plant. Dilute the fertilizer to half the recommended strength to avoid nutrient burn.

Repot the plant if you see water damage or mosquitoes

If you notice signs of water damage, such as yellowing leaves, a sour smell from the soil, or an infestation of gnats, it is time to repot your plant. Gnats are often attracted to damp, decaying organic matter, which indicates that the soil is too wet.

Carefully remove the plant from the pot, check the roots for rot and prune any damaged areas. Repot the plant with fresh, well-draining soil to encourage healthy root growth.

Extra tips: Avoid overwatering by allowing the soil to dry between waterings and make sure your pot has adequate drainage holes. If the plant is still healthy but is suffering from mosquitoes, you can Neem oil and spray regularly to kill the eggs and control reproduction.

Check the humidity

Many houseplants, especially tropical ones, prefer higher humidity. To maintain adequate humidity, group plants together, use a humidity tray with water and pebbles, or place a humidifier nearby. Misting the leaves of the plant can also help, but don’t overdo it, as too much moisture can lead to mold growth.

Rotate plants

Rotate your plants every few days to ensure that all sides receive equal sunlight. This helps prevent uneven growth and keeps the plant balanced. Rotating your plants also reduces the risk of leaf burn from prolonged exposure of the same leaves to direct sunlight. This is especially important for plants with delicate leaves.

For more houseplant tips, check out our list of hard to kill houseplants and find out which plants keep insects away.