I have for about 20 years grown amaryllis from a bulb bought in Holland . Most years I have given bulbs away in flower to charity raffles and such. I still have four bulbs growing, they flower each year. The most important thing in my opinion is to feed for a long period after they have flowered, leave all the foliage on, give them a dry period of about 3 months then cut the foliage and restart. I feed with any high potash feed but only after they have flowered. There is now thoughts about growing them green all the year round but I have not tried that yet.
