I have just bought a white Hydrangea, I would like to keep it in a pot, can I use general purpose potting compost and would this keep it white.
Yes it will grow in a pot and, if it's the paniculata type it will stay white and then probably fade to pink as the flowers age. Hydrangeas do need plenty of moisture to do well so if you do grow it in a pot you'll need to water, and feed, regularly through the growing season. Even the best quality planting composts only have food for about 100 days in them. After that it's up to you.
Thank you for your great information once again, would it need to be a general flower and plant feed.
I sugegst you incorporate some moisture retaining gel granules into the compost. And choose a pot that allows at least 2" clearance between the top of the compost and the lip of the pot, to allow for expansion as the gel expands, and to allow room for water to sit on top after watering and soak through
You can add slow release pellets of food or, if you prefer to be organique, mix some pelleted chicken, cow and/or horse manure at potting up time. An occasional liquid feed of rose or tomato fertiliser will do wonders too.
Stand the pot in a saucer for the summer so it doesn't drain all its water away but make sure it's raised on feet in winter so excess moisture can drain and avoid freezing the roots to death.
Thanks again for the great information. Just another question, we are having rather a lot of topsoil delivered for our new lawn and garden, if there is any left over is could we store it in some bags or containers and could I mix it with compost for for container plants. Also, we have had some drainage in our lawn I did read somewhere before putting the topsoil on to put 2ins of sand can you tell me which sort of sand if this is correct before they lay the topsoil which is begin delivered Wednesday. Thanks again for your expertise.
Yes you could mix the topsoil with the compost. However it will make the pots a lot heavier. That isn't a bad thing for pot grown shrubs that might otherwise be top heavy and unstable in the wind.