Pampering bulbs after flowering
As soon as the plants flower, a process begins in the bulb that develops sufficient nutrients to make sure that the bulb flowers again next year. That's why the tulips in the famous bulb fields are 'topped': the flower is cut off at an early stage so that all the nutrients remain in the bulb and are not used to form seeds.
In the garden
In the garden the bulbs must of course come to full bloom, but the flower can then be cut off. The foliage must however remain in place because that is the photosynthesis medium that makes sure that the bulb is supplied with sufficient nutrients. The stem and foliage must not be removed until they have completely dried out and turned yellow.
Bulbs that are destined to remain in the ground for a number of consecutive years will require extra attention in the form of fertilisers. These can be natural fertilisers such as compost or dried cow manure granules, or an artificial fertiliser. Artificial fertilisers generally contain a balanced combination of nitrogen (N), phosphorus (P) and potash (K). N-P-K 7-14-28 is recommended for light, sandy soils, and N-P-K 12-10-18 is best for richer types such as clay soil. We recommend adding the fertiliser in three portions, divided over the year. The first portion should be added in the spring when the bulb needs a boost and the last in late summer (August-September) to encourage the bulb to form new roots. However, the period immediately after flowering is most important to the bulb because that's when it accumulates new reserves, which means that in most cases it is sufficient to apply fertiliser just once at that time.