Preparation
Dig over the general area you are planting in beforehand to remove competitive weeds and allow the air content of the soil to rise, this will aid the entry of water
Waterlogging
Most bulbs hate waterlogging for any lengthy period. They are plants that prefer free draining soils, try and avoid such areas unless the bulbs are suited to it, Camassia and some Leucojum will tolerate a little waterlogging.
Planting Depth and Spacing
As a guide, the planting depth of soil over the bulb, for most bulbs, is two to three times the height of the bulb itself. A small crocus bulb only 1" long would go in 2-3" deep. Spacing betwen bulbs is largely dependant on the flower size - large flowers or large leaves need greater spacing. The each bag of bulbs ordered from Avon Bulbs will come with spacing suggestions as well as with brief planting instructions and a suggestion to the depth of planting, particularly for the few exceptions to the general rule, eg. Lilium candidum and Nerine bowdenii. The Eremurus or Foxtail lilies, hate being overshaddowed by other plants. They do need the sun to be able to get to the soil around the plants, thereby allowing the soil to warm.
Labelling
Do label your planting so that when the bulbs flower you will know what they are, but equally when they go dormant you will remember not to dig them up as you garden over them.
Feeding
Fertiliser in the form of bone meal or another form of slow release plant food, and leaf mould will help, but remember that this may well encourage weeds to grow more vigourously as well. Most bulbs only grow slowly through the winter and fertiliser is rarely limiting at this time. During rapid growth and flowering it becomes more critical as bulb mass is being exhausted and has to be replenished before the dormant period sets in again. Fast growing bulbs with bigger growth habits, the Crown Imperial Fritillaria for instance, will benefit from liquid feeding whilst in growth as they have so much ground to make up before they again go dormant.
Irrigation
Spring flowering bulbs tend to need a dry summer rest. Once the leaves wither they form a protective skin and wait for the soil to cool again and seasonal rain to trigger another growth cycle. Irrigation of other plants around them may therefore not be beneficial.
Dormancy
As the seasons shift the triggers to switch from growth to dormancy are activated and the physiology of the bulb beneath the ground changes.
The growing is done, flowers have been made, seed set and in preparation for a time of "stress" (hot dry weather for northern hemisphere bulbs, cool dry weather for southerners) the goodness of the leaves is recalled into the bulb and converted into starch, swelling the bulb. Next year's flower germ is formed (and its size depends on how the bulb has fared) and a new skin is formed. From the gardeners' point of view this can be an untidy time, desiccating yello leaves are not pretty and the urge to tidy up can lead to premature removal of this foliage. Do try and allow it to happen naturally.
Most bulbs then need a period of dry rest. Under trees and shrubs that are now in leaf the top layers of soil will slowly dry out as the roots remove the moisture. In borders the benefits of deeper planting mean that the activity on the soil surface is less likely to damage the bulbs at depth.
The skin will develop and harden (allowing us to lift, divide and store them safely should we need to). The return to growth is triggered by rising soil moisture levels in the autumn and/or cooling soil temperatures and the first sign of root development beginning again underground. It is probably now self evident how summer irrigation might confuse the resting bulbs.