The heat of summer is finally here! With temperatures set to soar into the high 90s and low 100s in the Pacific Northwest this weekend, the time is now to get your houseplants ready to handle the heat and switch into summer plant care mode.

Though some sun-loving plants like succulents and cacti are well adapted to high temperatures, plants that are kept indoors are not acclimated to the extremes of a summer heat wave. This includes your succulents and cacti (unless, that is, they’ve been moved outdoors onto the porch or patio for summer). Leafy tropicals are particularly susceptible to damage from heat, and if too severely damaged, might not recover.

Not to worry! There’s plenty you can do in advance of and during the heat wave to make sure your indoor plants survive the heat. Here are 5 of the most important summer plant care tips to get you started.

  1. Promote high humidity
    Plants that like high humidity (many epiphytes and tropicals such as fittonia, calathea and most ferns) should be frequently misted through periods of heat. You can also fill a shallow dish with pebbles, fill with water, and set your pot on top to create a little humid microclimate for your plant that will provide humidity and help your plants survive summer.

  2. Water well, and water deeply
    As you’ve probably read on our blog before, proper watering is key to indoor plant care. Though over-watering is the most efficient way to kill your houseplant, heat and sun cause water to evaporate from soil at much faster rates. In preparation for a heat wave, be sure to give your plants a deep watering – if you water too quickly or not enough, often just the top of the soil gets wet and the rest escapes down the sides of your pot and out the bottom. Make sure the water is actually absorbed by watering slowly, and allowing the plant to soak up excess water in a bowl for 10-20 after watering.

    While you’re in summer plant care mode, check your plants soil moisture level more frequently than normal, either by using a moisture meter, or with the trusty “finger test” – water when soil feels dry at 1-2″ down for most tropical plants. Another key indicator of fast-drying, compacted soil is when the soil pulls away from the sides of the pot. If there’s a gap between the soil and the side of the pot, it’s time to rehydrate!

    If you happen to have A/C, keep in mind that the dry air can dry pots out just as quickly as the sun. Keep an eye out for thirsty plants and water well.

  3. Shade sensitive plants from too much sun

    Plants get sunburn, too. Plants that live in south and west-facing windows will get an especially bright dose of vitamin D during this weekend’s heat wave. But since you can’t put sunscreen on their leaves, it’s best to move them a bit further into your house to spare them from this direct hit of the sun. As mentioned at the top, this goes for succulents and cacti that haven’t been acclimated to direct sun, too.

  4. Keep it cool
    If you’ve ever felt faint in the heat, imagine what your plants must feel like! Do your best to keep your plants out of the hottest spots in your home while in summer plant care mode. This might mean moving them away from windows or even into other rooms during hot times.

    Also, it may seem counterintuitive, but the best way to keep your house cool in the heat (assuming you don’t have A/C) is actually to close your windows during the day when the heat is on, and open them back up at night when it cools down. If you can manage to get the house just a few degrees cooler, you’ll feel a lot better, and so will your plants!

    Photo by Folia Collective
  5. Don’t fertilize during a heat wave

    Though fertilizer is your friend, especially during summer, a stressed plant should never be fertilized until it recovers. When your plant is in summer survival mode, it’s not looking for extra nutrients and isn’t prepared to make use of them. Introducing these into the soil will risk further stressing your plant. Wait until it cools down a bit for your next feeding!

  6. Don’t re-pot during a heat wave

    Likewise, you shouldn’t choose a 100+ degree day as the perfect moment to re-pot that root-bound ficus (or any other plant for that matter). Why? Leaves always get damaged during re-potting (and in fact, proper re-potting often involves trimming away a lot of the root mass). Re-potting will cause your plant to get a bit stressed (even though it’s important plant maintenance in the long run) and this added stress could cause it to fail during the heat.

  7. Wait to prune

    Why wait to prune off damaged leaves and stems until after the heat wave passes? You guessed it: stress. While a little pruning here and there often helps your plant spur new growth, immediately assuming that a leaf that’s wilted or discolored is a goner is not the best choice during a heat wave. When conditions get back to normal, the leaf might rebound. Plus, it might still be supporting the overall health of the plant. And, of course, pruning does cause a bit of stress to your plant. It’s best to wait until temperatures get a bit back in the normal range before snipping off leaves and stems that didn’t make it.

  8. Learn to recognize stress

    Last but certainly not least, being ready to catch problems early is key to stopping them before they take hold and ravage your indoor plants. Common signs of stress to keep in mind for summer plant care usually have to do with too much heat and too little water.

    – Tropical plants, especially those with tender leaves, usually wilt with exposure to too much heat.
    – Foliage that was once bright green may look pale when stressed.
    – Sunburn manifests in a variety of ways, but often looks like a rough brown or yellow patch on leaves/stems.
    – Flowers (and leaves) often drop off or yellow when a plant is stressed

Now — what about your outdoor plants? Here’s some hot weather gardening tips to make sure your landscape stays green through the heat, too!

How have your indoor plants fared during the heat this summer? What summer plant care tips have given you good results? Share with us in the comments!

Pistils Nursery