British gardeners are bracing themselves for another scorching heatwave, with temperatures in some parts of the country soaring to around 30C by the weekend. The heat brings with it another challenge – plants surviving under the intense sunlight especially with the threat of a hosepipe ban around the corner.
Garden expert Simon, from the Walking Talking Gardeners YouTube channel warns of a rookie mistake that many, if not most, gardeners make when it comes to removing plants from their greenhouses or when they buy them from garden centres. Simon explains that, while greenhouses are a boon through the colder months, they can become a “death trap” for plants when the summer is in full swing.
He adds that there are three main tricks to ensure that plants that have been grown in a greenhouse survive the summer heat. First, he suggests, is buying some greenhouse whitewash to turn the south-facing wall of your greenhouse into a reflective surface.
Secondly, Simon advises watering not only the plants, but the floor of the greenhouse as well – as the water evaporates it will provide additional cooling.
But the third, and most important tip, Simon stresses, is to “get your plants out of the flipping greenhouse”. “They shouldn’t still be in there at this time of the year,” he added.
Yet there is one specific rule that anyone who has just bought new plants should abide by. Simon continues: “You can’t just put them out and plant them up into their final position because they will be scorched from the sun.
“When they’re in the greenhouse, they are under protection from the UV light. If you bring them out into full sun, the sun rays will scorch them – the same as you being very pale and going out in the sun and getting an absolute sunburn, it is very easy to scorch these plants.”
Instead, he advises that you should “harden” plants by placing them in dappled shade, such as under a small tree, until they’re a little more acclimatised to outdoor life.
“Over a period of about 10 days or so, they’ll build up their resistance to the sun, and then at that point, they can go outside into full sun.
“It’s an important job. It’s not really spoke about much, but the hardening off of plants is absolutely critical.”
He adds that plants that have had plenty of TLC in a garden centre will also need the same treatment: So many times you’ll be purchasing plants from your garden centre. They have been kept under protection. You plant them out. Next day… dead.”
As always, you should ensure that plants in pots are well-watered – remembering that pot plants’ leaves will tend to keep rain out of containers.
Simon adds that you should bear in mind that different pots lose water at different rates. “Terracotta pots and concrete or stone pots are porous and will evaporate moisture through the sides of the pot,” he says.
“So, these lose water very quickly and will need more watering than plastic pots or glazed terracotta pots.”