Adding used teabags to garden soil can turn hydrangeas a stunning blue, according to gardening experts. The tannic acid in tea lowers the soil's pH level, increasing acidity and making aluminum more available to the plants, which results in blue flowers.
How Teabags Change Hydrangea Colour
Graham Smith, a gardening expert from LBS Horticulture, explained: "Adding teabags to the soil will change the colour of hydrangeas because tea contains tannic acid, which lowers the PH level of the soil and increases its acidity." Ted Bromley Hall, managing director of IBRAN Limited, added: "The colour-changing ability of hydrangeas is directly related to the soil level and aluminium availability. When the soil is acidic (pH below 6.0), aluminum becomes more available to plants, resulting in blue flowers."
Simple Application Method
To achieve blue blooms, bury used teabags near the plants' roots. Alternatively, brew the teabags to make a black tea fertiliser, which provides essential nutrients like nitrogen, phosphorus, and potassium that are vital for plant health. This method is cheap and effective for experimenting with flower colours.
Check Soil pH First
Before using teabags, gardeners should know their soil's pH level. Soil pH metres, available at garden centres or online for £10 to £15, offer accurate readings. A cheaper DIY method involves using baking soda and vinegar: place soil samples in two glasses, add vinegar to one and a mixture of water and baking soda to the other. If the vinegar sample bubbles, the soil is alkaline; if the baking soda sample bubbles, it is acidic. No reaction indicates neutral soil, but a pH metre is recommended for verification.
