I visited a garden shop today that was well equiped in supplies I thought. I was looking for water soluable fertilizer that was high in potassium to use after fruit set. The only thing I found was a blend of 18-18-21. Is their something better suited I can use or is this a common blend. Could muriate of potash (0-0-60) be used incorporated along the runners in late season? Would sulfate of potash (0-0-50) be better for pumpkins than the muriated kind?