While sunlight is required for pyrethrum flowers, reports are mixed as to how much or how little is required.  One key acknowledgement is that hours of sunlight in a given day, determines the plant’s flowering pattern.  Namely if the plant flowers most of the year and, or if there is only one or two flowering periods during the year.  For example in East Africa where the hours of sunlight are relatively similar throughout the year, the pyrethrum plants have two major flowerings due to seasons, but also flower a majority of the year, allowing a steady income for many months.  In Australia, the hours of sunlight varies significantly between seasons and the long sunlight hours and warmer weather in the spring and early summer results in near synchronous blooming in late spring, early summer.