Verbascum phlomoides 39banana custard39 is a dramatic plant for the back of the border with tall yellow flower spikes rising above low rosettes of grey45green foliage from june to august often grown as a biennial or short45lived perennial this striking architectural plant is prized for summer bouquets and loved by pollinating insects allow it to self45seed after flowering and youll have a new batch of mullein plants next spring that will flower the following year height 1