I have a special affection for Evening Primrose. Years ago I saw a packet of seeds for a large flowered but dwarf variety of Evening Primrose, I believe they are called Oenothera missouriensis – I managed to grow a couple of plants and have enjoyed their blooms ever since. This wonderful, tropical looking, bright yellow flower blooms from early Summer until the frost and is now at its most beautiful.
Dwarf Evening Primrose
The plants have always remained fairly compact once they reached this particular size so have never required thinning out or cutting back. For those who prefer the traditional Common Evening Primrose, then note that they are not perennial as with those above but are biennial, flowering on the second year of growth before dying back. The larger ones are Oenothera biennis and unusually for flowers they only open on dull days and evenings.