Thanks for the feedback. I have had a good look on the web and have ordered some chelated iron (which also contains magnesium) and will give them a foliar spray. It seems that the worse thing to do is to be too kind to them and fertilise them. However they can suffer from iron and it seems magnesium deficiencies. Our soil is sandy and light so it is well drained. Have bought and planted some banksias from an English nursery that specialises in them (The Old Walled Garden in Kent) and they are surviving well, although one of them is looking a little yellow (*gulp*) so I'll go down the iron/magnesium and no added fertiliser route. If this works then I'll have a go at some more seeds. The mix that I started them off in was a mixture of sand, potting compost and perlite, roughly thirds. Thanks for the help and encouragement.

I've got Honey screen in my natives garden and it's been growing steadily for about 2 years now. It's looking good and growing nicely with just a little prune once a year. It's facing north-east, just west of Tweed Heads, NSW.

just a follow up from what Funnel web said treat most native carefully when re-potting or rot-pruning. I would also like to add if you do a light top prune or even if you don't, it good to give plant a TE feed (trace element) in pot. Now yellowing on leave is a TE deficiency it is a magnesium deficiency, magnesium get leeched out of the soil in winter, and also can happen after flowering. To fix the problem is to add one teaspoon of magnesium or ( Epsom salts), to a 9lt water can and give the plant a drink at soil level. Now if you have yellowing on new and young leave, it a sign of Iron deficiency to fix this to need to put a teaspoon of Iron chelate in in the water can and water at soil leave Please Note : the magnesium or Iron will not fix the leaves that are already yellow it will help the new growth leaves coming through. If I was you I would go down to your local garden store or Nursery ask them about Re-potting banksia and what they think and also ask them. Do they have (JUST have a Complete Trace Elements feed)? The Complete Trace Element feeds have all the TE in it including magnesium and Iron Regards Benjamin Manning Canelands nursery This post was edited by Benno88 on Wed, Oct 23, 13 at 8:15

I think your plant needs a lot more sun. Probably not the best choice for the balcony. https://www.gardeningknowhow.com/ornamental/flowers/banksia/how-to-grow-banksia-plants.htm https://www.anbg.gov.au/gnp/interns-2002/banksia-ericifolia.html