Blindness is the failure of a plant to flower despite producing healthy foliage and is a common problem with bulbs. It is the result of a malfunction or absence of the growing point.
There are a number of possible causes which include attack by pest or disease, such as a large infestation of bulb fly or in the case of narcissi it could be basal rot. It is however more often due to cultural conditions. Dry soil conditions or a lack of nutrients can result in a decline in bulb size leading to them being too small to flower. Blindness can also affect very crowded clumps of bulbs that are competing for moisture and nutrients, naturalised bulbs that have not been fed and bulbs growing in dry soils.
As well as ornamental plants, blindness can also be a common problem in brassicas, especially broccoli and cauliflowers and is usually the result of the plants receiving a cold spell at a critical stage of their development.