Colour by numbers :
The colour of hydrangea flowers is determined by the pH level of the soil. Acidic soil (pH of less than 5.5) will produce blue flowers, while alkaline soil (pH of higher than 5.5) produces pink blooms. You cannot change the colour of white hydrangeas.
- For blue hydrangeas : Make soil more acidic by adding acidic peat to the soil. Feed plants with 25g of aliminium sulphate dissolved in 5 litres of water at two-weekly intervals from early spring onwards. Feed with Shake n Grow Blue Hydrangea Plant Food.
- For pink hydrangeas : Make soil more alkaline by adding agricultural lime to the soil. Dust lime at the roots of the plant and water in well at two-weekly intervals from early spring onwards. Feed with Shake n Grow PinkPink Hydrangea Plant Food.
If you struggle to obtain the colour that you would like, try planting hydrangeas in pots instead. It is far easier to manage the pH level of soil in a pot than in an entire garden bed. It may also be worth checking the pH of your tap water (you can use a pool test kit to do this). The pH of the water may determine the colour that is most feasible to aim for in your garden.
Pruning hydrangeas :
Hydrangeas should be pruned twice a year – in winter and in summer, just after they have finished flowering.
The winter pruning (ideally in June or July) is the harder pruning session. Remove all the dead, old or weak stems. Prune all the remaining stems back to just above a cluster of buds. The idea is to channel all the plant’s energy into producing new flowers. After pruning, feed with hydrangea food and mulch the soil well (an acidic mulch like pine needles works well if you are aiming for blue flowers).
Summer pruning (ideally at the end of January) entails cutting off any dead flowers and removing dead or old stems. Add plenty of compost to the soil to encourage the next season’s growth and mulch well to conserve water in the soil.
To read more about Hydrangeas click here
Text and tips via here
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