If you’re looking to add a burst of colour to your garden this spring, hydrangeas are an excellent option. These popular flowering plants typically bloom from mid-spring to late summer, although the exact timing can vary depending on the specific variety and growing conditions in your garden.
Hydrangeas are known for their striking flowerheads, which come in a variety of shapes, including balls and cones. The blooms are available in a range of colours, such as blue, pink, purple, and white. However, the colour of the flowers can be influenced by the type of soil in your garden.
According to the Royal Horticultural Society (RHS), the pH level of your soil plays a crucial role in determining the colour of hydrangea blooms. Acidic soil (with a pH of 5.5 or lower) tends to produce blue flowers due to the presence of aluminium, while alkaline soil (with a pH of 6.5 or higher) usually results in pink blossoms.
For those who prefer vibrant blue flowers, there is a simple way to alter the colour of hydrangeas: adding coffee grounds to the soil. Coffee grounds are acidic and can naturally lower the soil’s pH, making it more acidic and conducive to producing blue blooms. This method has been reported to be effective by various gardening enthusiasts.
The coffee grounds help make aluminium more available to the hydrangeas, which in turn encourages the growth of vivid blue flowers. However, achieving the desired blue hue is not an instant process; it requires patience and consistent effort. To speed up the transformation, gardeners can also add aluminium sulphate to the soil.
Planting Tree notes that while some people have successfully used coffee grounds to change the colour of their hydrangeas, this method is not guaranteed. Coffee grounds can naturally integrate into the soil, making it a low-risk experiment. For more reliable results, gardeners might consider using products specifically designed to increase soil acidity.
To achieve the best results, sprinkle the coffee grounds around the base of the plant, ensuring they do not touch the stems. Gently mix them into the soil either by hand or with a trowel to promote decomposition. Composting the coffee grounds before applying them to the plant’s base can also improve soil nutrition and health by providing a broader spectrum of nutrients.
Gardener’s World adds that the moist, small particles of coffee grounds are an excellent compost ingredient due to their texture. Mixing them with dry and woody waste can speed up the composting process. A balanced mix of “wet” and “dry” materials is essential for effective composting. The nutrients in coffee grounds will be recycled back into the soil when the finished compost is used as mulch or dug into the soil. Additionally, any undrunk coffee can be added to dry material in a compost bin.
While coffee is slightly acidic and beneficial for acid-loving plants like hydrangeas and nutrient-hungry plants like roses, it should be used in moderation to avoid over-acidifying the soil.
