It is important to plant bulbs at the correct depth and the right way up. As a general rule they should be planted at about twice their own depth for the larger bulbs, the very small bulbs require about 5 cm of soil above them.
Most bulbs require a well-drained rich soil with sand/grit and humus, chalk is preferred to a very acid one. Many of the Dutch bulb fields consist of dune sand which have large amounts of shells in it providing lime, enriched with humus, so that it is both moisture-retentive and well drained, as well as alkaline and fertile.
If bulbs are to be used for bedding and discarded the fertility of the soil is not important. If they are planted as a permanent feature, then it is essential that the soil in which they are grown is very fertile. The best fertilisers are low in nitrogen, high in potash and phosphate, e.g. Vitax GRR, Rose fertiliser, Palmers Supergrow or the one that I use is based on an old formula of Guy Wilson, the great Irish daffodil hybridiser, and consists of a mix of 1 part hoof & horn (med grade), 5 parts super phosphate, 5 parts bone meal (med grade) and 5 parts sulphate of potash, which is applied at a rate of 4oz to the square yard.
Pot grown bulbs should be grown in good quality compost and you can either use a propriety mix of good quality, JI No 3 loam based compost or a soil-less one. In both cases I would add extra grit/sharp sand at the rate of 1 bucket of compost to one of grit.
Or you could mix your own and I would recommend either a good turf stack, this is the off cuts obtained from any good turf merchant stacked grass side down, layered with well rotted manure and dressed with lime. This is covered over the top with polyethene or corrugated sheets with the sides open for about 12 months, this can then be chopped up and riddled or you should be able to buy loam from the supplier of your JI compost. The mix I use is 1 part loam, 1 part sharp grit 1/8” or 3mm down, 2 parts Irish moss peat medium grade. To 8 gallons of this mix I would add 12 oz of my mix of fertiliser plus one 5” plant pot of charcoal.
If the mix was going to be used with species or alpine type bulbs where extra drainage is an advantage I would add extra grit at the rate of 1/2 bucket of grit to one bucket of the loam mix.
pots during the growing season
I use either Chempack No4 or
No8 at the suppliers recommended
rates and 2 feeds of sulphate
of potash per season at the
rate ¼ of a teaspoon
to 3-5” pot, or 1 heaped
teaspoon to a 10” pot.
One feed should be applied once
the shoots are through a little,
and other after flowering.