Posted: 25/07/2013 at 17:38
Re the heleniums, I would not feed too much. In such a small pot and the roots so restrained I would loosen the roots, teasing out as much as possible, and then put into bigger pot. Then WATER. Water well. Water again. Keep in shade for week or so. This sounds horrible but if you have any flowers cut them off and all old stems. They will recover.......to flower next year. Possibly they will flower in September this year but keep watered but not drenched after your initial soakings.
Re dierama. They don't need marshy or boggy ground at all. Just as Nut says, they LOOK good by pools, etc., but need good soil. In my experience they do need extra water when initiating flowers.....viz. In early June.....and up to and including flowering time. I have Guineveire, a superb white. If this is going into a pot I would use John innes number 3 with a little dried manure added.