Although it’s true that generally speaking houseplants are better suited to coping with hot, sunny weather than cut flowers, they still need a little extra care and attention when the mercury starts to rise.
How do high temperatures affect houseplants?
If any plant suffers severe water loss, it has to work harder to try to find what water it can, this depletes its resources and can lead to complete collapse.
What is the ideal temperature in summer?
Most green plants are happiest with a constant summer temperature of around 18°C but will tolerate a maximum of 24°C (75°F) with only a very few, Cacti being the obvious exception, enjoying it any hotter. Bear in mind that sunshine through glass causes a greenhouse effect which significantly raises temperatures.
Displaying houseplants in hot weather
Always display your plants out of direct sunlight which can scorch and damage the leaves.
If you are displaying plants in a window, make sure that they are shaded from the sun, particularly at midday and don’t forget the sun moves round.
Rotate your plants so that they all get the benefit of air circulation.
Houseplants appreciate fresh air, especially in summer so they can be displayed in a shady spot outside.
Containers
Plastic pots heat up more quickly than ceramic or stone and will warm the compost, potentially causing stress to the roots.
Terracotta is ideal for pots in hot weather, as its porous nature allows for moisture and air to be exchanged which helps to maintain a more consistent temperature.
Watering
Check compost frequently, and be prepared to water more often than usual, but still only when the top 2cm of the compost is dry.
Tepid water will cause less shock to a warm plant than cold.
If displaying plants in a gravel tray don’t forget to keep it topped up.
Spraying regularly will help to maintain a humid atmosphere.
Dealing with heat damage
If leaves do get scorched by the sun, they will not repair themselves. If the damage is small, cut the area away with a pair of scissors, if most of the leaf is affected then it will need to be removed entirely.
To help a sunburnt plant recover, move it to a bright spot, where there is no direct sunshine. Don’t put it in the shade, as it still needs light to help it to produce new growth.
Customer advice
If your customer is going away on holiday, recommend that they move their plants off windowsills and out of conservatories and porches where temperatures can rise significantly.
Plants can be temporarily left in cooler, shadier rooms such as bathrooms or utility rooms.
Su Whale is a florist and freelance writer with over twenty-five years' experience in the floristry industry. She is the author and publisher of three best-selling books: Cut Flowers, 4th edition (2020) Cut Foliage, 2nd Edition, (2021) and Houseplants (2019), all bookshelf essentials for the professional florist.
