Fall is the prime time for planting hardy, spring-flowering bulbs
Bulbs and perennials need plenty of water and good drainage. If water tends
to stand in your planting area, you'll want to break up hard subsoil and
put in a layer of drainage material such as coarse gravel, broken stone or
sifted cinders below your surface soil.
Summer-blooming Dutch bulbs and perennials
are not fussy about soil,
provided it is not too heavy or sticky. If soil is heavy, loosen it with
lots of humus, sand or gypsum. If very light, add moisture holders such as
humus or peat moss. If you have soil with a high clay content, it can be
improved by adding compost, peat moss or some other organic material. The
organic material should be worked into at least the top 30 cm of soil and
preferably the top 45 cm.