Dear Sven,

What type of soil do blue hydrangeas like to grow in? I would really like to grow some in a pot by my front door if I can.

Thanks for your advice!

Rosemary

Our Gardens Expert replies:

Dear Rosemary,

Hydrangeas are a really easy flower to grow - I have turned up to many a shabby old garden in need of a redesign and the only survivors holding their showy flowers above the weeds are the good old Hydrangeas!

Hydrangeas turn blue when there is a presence of aluminium in the soil. The saturation of colour in their petals depends on how healthy the plant is, what the weather is like and how much acid there is in the soil. In acidic soil the aluminium is more easily available to the plant so therefore the flowers are usually bluer.

It is the PH of the soil that determines the colour of the petals - acidic soil produces blue flowers, neutral soil produces near white flowers and the more alkaline the soil, the redder the flowers become. In most cases the flowers are white but as well as blue they can be red, pink or even purple.

The beauty of growing Hydrangeas in pots is that you can control their environment. To encourage bluer flowers, you could plant them in ericaceous soil. This is not the case for all Hydrangeas but the best for this purpose is Hydrangea macrophylla which is one of the most effected by the soil PH.

The ideal position for them is somewhere a little sheltered and out of the midday heat, ideally with a bit of morning sun and dappled shade for the rest of the day.

They work really well in pots by a door and to be honest, would make a nice change from the somewhat over used clipped bay or box that every 'trendy' home shop seems to sell these days!

Happy potting!

Sven