Growing hydrangeas

The recent mix of rain and sunshine has had an effect on all of the garden. All around I am seeing new growth and greenery. I'm particularly pleased to see my hydrangeas doing well at the moment as I have had some problems with them in recent years. Hydrangeas provide a vibrant and abundant display in the summer. They also make good cut flowers. In all they need little maintenance so they are well worth growing in your garden.

Types – There are three main types of hydrangeas. The two most common ones are mophead and lacecap plus the more unusual paniculata.

Mophead hydrangeas have large heads completely covered with petals. They are also known as pom-pom, bigleaf, French or hortenisa hydrangeas.

Hydrangeas which have tiny flowers circled by larger ones are the lacecap variety. Often the centre flowers are a different colour to the outer ones.

The third type is the paniculata. The flower heads of these are a cone shape or in botanical terms a terminal panicle.

Planting – Hydrangeas are known for their ability to change flower colour. This is the case for some varieties but not all. This is down to the pH of the soil they are planted in. Hydrangeas are affected by the aluminium available in the soil. If the soil is acidic then the aluminium available is higher. This leads to pink flowers turning blue. Acid to neutral conditions turn the flowers mauve. If the soil is more alkaline this gives pink flowers. 

Hydrangeas which have white or green flowers will not have their flower colour affected by the soil pH.

Hydrangeas are not fans of full-sun as they like moist but well-drained soil. Cold winds can damage the new buds in the spring so also keep them protected from such areas. Ideally they like to sited in a cool, semi-shaded spot.

You can grow hydrangeas in pots but they will need a little care and attention given to them. They are a garden plant and don't do as well when kept inside. Make sure whatever pot your hydrangea is in is quite large and has decent drainage in it.

I don't use any fertiliser on my hydrangeas but if your soil is not particularly good then some added nutrients will be welcomed. This can be done in late winter or spring by adding some type of mulch to it. You can use homemade well-rotted leafmould or compost for the job or buy some.

Annual chop – Generally hydrangeas simply need their old flower heads cut off and a cutting of deadwood down to new growth. When you actually do the cut is down to you. I prefer to do it towards the end of May when the risk of a late frost has passed. However I have seen plenty of hydrangeas where the old flower heads have been snipped off in autumn and next year's growth has not been affected.

Common problems – Over the years we have noticed a white, mould-like substance on the leaves and wood of our mophead hydrangea. This is a pest known as hydrangea scale. A few won't do your hydrangea much damage but one year it ours was covered and it was noticeable how it affected the all-round growth of the hydrangea. You can spray the hydrangea with a pesticide but this is not something I am keen on. I don't think that such chemicals do the garden any good and can kill pollinating insects.

If you want to go down the more organic route for treatment then you can painstakingly wipe the leaves clean. This can be done by adding a very small amount of washing-up liquid to water. The alternative method we used was to give the hydrangea a very harsh cut. It did mean that we had a summer with very few flowers but now the hydrangea has come back and looks very healthy.

Do you grow hydrangeas? What's your tip for keeping them looking great?