Hydrangea care guide
The mop head Hydrangea (Hydrangea macrophylla) would have to be one of our most loved and best selling items. Spectacular in flower during the Summer months, great for a shaded spot and very hardy, your Hydrangea will give you so much joy year after year.
Where to plant
Hydrangeas need a semi shaded area and protection from hot afternoon sun. They will grow in most soils, including heavy clay and are salt tolerant so you can even grow them on the coast.
Plants in heavy shade will still grow, but will have more flowers if they receive some dappled or morning sun, and if planting underneath an established tree, be aware that your Hydrangea will be competing for water, so you may need to adjust your routine. Your Hydrangea will grow to around 1.5m in height and width, so make sure you give it enough room to grow to its full potential. Importantly, allowing enough space for your Hydrangeas will ensure there is enough air flow around plants and will help prevent fungal infections.
Pruning
An old, woody and leggy Hydrangea can be brought back to vigorous bushy growth with a good prune in Spring. After flowering, remove canes that are more than 3 years old right to the base. Stems with last years flowers can be pruned to the first pair of double buds lower down the stem. New growth that hasn’t yet flowered should not be pruned unless damaged at the tip. In this case, tip prune only.
Watering
Hydrangeas need to be well watered in their early years. As the shrub gets older and more established it will be better able to cope with dry conditions. Hydrangeas will tell you if they need water, as the stems will appear droopy but will recover quickly once watered. Mulching is recommended to help reduce water stress. To reduce the chance of fungal diseases like powdery mildew, water the soil, not the leaves.
Picking flowers
If you plan to use Hydrangeas for cut flower arrangements, make sure you pick them when they are fully formed, as unformed flowers will not continue to develop once to you pick them. Pick later in the day when the temperature is cooler, and cut the stem lower down on the bush so it will come back with beautiful new growth and flowers next year.
Flower colour
The colours of the Hydrangea flowers can be manipulated to some extent by adjusting the pH of the soil, but it can take some time. Applying a blueing tonic or adding aluminium sulphate to the soil in the lead up to flowering season can create a more blue toned flower, while adding lime or fertilisers that are high in phosphorous can help keep your Hydrangeas pink. White hydrangeas will stay white, but may colour slightly around the edges of the petals.
Fungal diseases
Common fungal diseases that affect Hydrangeas:
Botrytis Blight: Brown petals falling to the ground, buds form but then die before they open.
Cercospora Leaf Spot: Leaves have tan spots surrounded by brown halo.
Powdery Mildew: Grey/white powdery substance on leaves.
Rust: Orange spots (spores) on the underside of the leaves.
Hydrangeas don’t suffer too much from pest and disease issues but can experience some fungal diseases which can be controlled both with fungicides, and cultural practices such as watering the soil instead of the foliage, removing infected leaves and spacing plants out to maximise air circulation.
