Then it would be too much water.
Silverbeet will usually grow well with minimum attention in Melbourne.
Its rotting.

Lionel van den Berg wrote:
Jonno wrote:
Im not sure, but it would suggest that they are not getting enough
water, are placed in full sun.
Put them some where less exposed and allow better watering. no
problems in Melbourne with this kind of thing....

Well actually, I've been watering like crazy, we've had storms recently
and they are in about 65% sun.