Gardeners are being warned of a common mistake to avoid when moving plants from greenhouses, as the UK braces for a July heatwave – with temperatures in some areas set to reach 30ºC by the weekend
British gardeners are gearing up for another blistering heatwave, with the mercury set to hit a sizzling 30C in some areas by the weekend. This sweltering weather poses a fresh challenge – keeping plants alive under the fierce sun, particularly as the threat of hosepipe bans looms.
Gardening guru Simon from the Walking Talking Gardeners YouTube channel has flagged up a common blunder that many green-fingered enthusiasts fall foul of when moving plants out of greenhouses or purchasing them from nurseries. He points out that while greenhouses are a godsend during the chillier seasons, they can turn into a “death trap” for foliage during peak summer.
Simon shares three key strategies to help greenhouse-grown plants withstand the summer scorcher. First of all, he suggests, you could consider applying temporary whitewash to the greenhouse’s south-facing wall to create a reflective barrier.
Next, he suggests not just watering the plants but also dousing the greenhouse floor, which helps cool the air as the moisture evaporates.
However, the top tip Simon emphasises is to “get your plants out of the flipping greenhouse”. He insists that by this stage of the year, they really shouldn’t be cooped up inside anymore.
But for those who have just snapped up new plants, there’s a golden rule to follow. Simon warns: “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,” Simon explains, “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 suggests “hardening” plants by situating them in dappled shade, for example beneath a small tree, until they’ve adjusted to the great outdoors.
Over a period of about 10 days or so, they’ll build up their resistance to the sun at which point they can go outside into full sun.
Simon stresses: “It’s an important job. It’s not really spoken about much, but the hardening off of plants is absolutely critical.”
He also points out that plants that have been pampered in a garden centre will need the same care. He continues: “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, make sure potted plants are well-watered, keeping in mind that leaves on pot plants tend to shield rain from reaching the container.
Simon also notes that different pots lose water at varying speeds. “Terracotta pots and concrete or stone pots are porous and will evaporate moisture through the sides of the pot,” he explains.
“So, these lose water very quickly and will need more watering than plastic pots or glazed terracotta pots.”