Hi, welcome to G o y, these are half hardy - frost tender shrubs or trees, should be grown in a greenhouse, and kept frost free, some can withstand short periods down to freezing, they should be grown in a mixture of john innes no 1, grit, and peat or peat substitute, equal parts, water sparingly in winter, and pot them on in spring, they will eventually get too big for your greenhouse, so unless you want to spend a fortune on heating, I would give them to your local parks dept, {if they will take them}, Derek.

Hi Derek. Many thanks for the prompt response. From what you say, I guess the bushes I saw would thrive in the Scillies, which is reputed to have a sub-tropical climate, but which Swindon decidedly does not. My seedlings are in ordinary general-purpose compost, and as they are doing well so far, I am loth to disturb them by adding grit etc - unless you advise otherwise. I have no proper greenhouse, only a plastic-covered frame type, with no way of heating it. I guess I could bring them into the conservatory, though that gets pretty cold during the winter, but I can add some heat if needed. Is there any kind of ideal temperature? I will have to move them soon, as I already have to bend the taller stems to get them in and out of my mini greenhouse. What about feeding? Do you recommend anything in particular and how often? So far they have survived on rainwater. I will investigate suitable future homes for them. Thanks again, Alan.

Hi Alan, a conservatory would be ok, if you can keep a minimum winter temperature of 5 deg c you should have no problems, I would leave them in the compost they're in, until you repot them next spring, then use the grit etc, water sparingly in winter, and don,t feed them until growth starts next year, when you should use a phosphate free liquid fertilizer, at half strength, once a month, and water as needed, you can put them outside when all danger of frost is passed, Derek.

Thanks Derek. That's very helpful. I'll do my best. Alan.

Hi Derek
My Banksias are OK at present in the conservatory, temperature usually 5-10 deg C and watered when I remember! The ones like the one on the left in my original picture are now about half as high again as they were then, while the others have grown more, now about 2 feet high. I was wondering whether I ought to nip out the tops to encourage side shoots. If so, is this the time to do it or should I wait a while? Would appreciate your advice. Alan.

Hi Alan, yes this is the ideal time to nip out the tips, just as growth starts in spring, I would also repot them in spring after they have been in growth a few weeks, {although, by the sound of it they have never stopped},
check to see if they are potbound, and if so do it right away, Derek.