We're quickly approaching the end of April which means rhubarb will be ready to be picked. However, gardeners growing the vegetable have been issued an important warning ahead of harvesting.

Rhubarb is commonly grown across the UK as it thrives in the cool climate. The vegetable, known for its tart and crisp red-to-pink stalks, usually starts growing at the start of February with harvesting running from the end of April. Although the stalks are safe to eat, gardeners are being urged not to consume rhubarb leaves.

Experts from Healthline, a health website, said: "Rhubarb leaves are considered inedible due to their high concentration of oxalic acid. In fact, both the stalks and leaves contain oxalic acid, but the leaves have a much higher content."

Oxalic acid, a natural substance, is found in a number of plants, including fruits and vegetables. However, rhubarb leaves contain around 0.5% to 1% oxalic acid by weight which is a much higher concentration than what is found in the stalks.

Healthline added: "Too much oxalate in the body can lead to a condition known as hyperoxaluria, which is when excess oxalate is excreted in the urine. This can also lead to an accumulation of calcium oxalate crystals in the organs."

This can lead to kidney stones or even kidney failure. Meanwhile, the main symptoms of rhubarb leaf poisoning include vomiting and diarrhea.

Healthline continued: "More serious oxalate toxicity causes sore throat, difficulty swallowing, nausea, vomiting (sometimes including blood), diarrhea, and abdominal pain.Very serious symptoms include kidney failure, numbness, muscle twitches, and cramps."

Dr Rosemary Trout, food scientist and professor at Drexel University, told Delish: The leaves are very high in oxalates, so you should not consume the inedible and poisonous leaves. Oxalates are anti-nutrients because they bind minerals, reducing mineral bioavailability. The insoluble oxalates can form crystals associated with kidney stones."

Rhubarb leaves are also toxic to pets, potentially causing kidney failure and tremors. On the other hand, rhubarb stalks are not poisonous, making them perfect to use in puddings, jams and pies