Surrey,
United Kingdom 
Rudbeckia are another plant I find impossible to grow unless in a pot that they grow rapidly out of and by that time late summer my ground is like concrete if I do try it I'm there every night trying to water it as they are so hungry
28 Jul, 2018
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I would wait until early spring and you can dig them up, divide them and replant. You need to prepare the planting area and deep dig with some old compost, peat or any other discarded potting compost. You can even incorporate a little grit or sharp sand so your watering is absorbed when it's bone dry. Yes they do seem to be thirsty plants but always manage to come back. I have had the same problem with mine in the past.
28 Jul, 2018