Why did my lupines die?
In respect to this, why are my lupines dying?
Soil that is too heavy, too wet or has too high a pH causes iron chlorosis, signaled by a yellowing of the lupine leaves, and root rot caused by fungi of the Rhizoctonia and Fusarium genera. Root rot inhibits seed germination and causes a general decline of the plant.
Also, do you cut off dead Lupin flowers? Lupines generally bloom from late spring into early to midsummer, depending on the variety. When most of the flowers on a spike have faded and before they've dried and set seed, deadhead by cutting the spike off with a sharp knife or garden shears.
Similarly, you may ask, do lupines die back?
Lupine stalks can be cut back in mid August, or any time after the seed pods have opened (or you have gathered them). The leaves will be building root reserves for next year's flowering until they die back in November. They will bloom starting in June of their second year.
How do you take care of lupins after they bloom?
Lupins prefer well-drained soil which isn't too rich. Lupins do not take too kindly to being chopped back hard after flowering - they take months to recover. If you have a good plant, don't let it produce lots of seeds. Keep the vigour in the parent plant and deadhead as the flowers fade.