Normally irises prefer light soils but the English varieties do best in the heavier lands. Prepare the ground as advised for. Plant the bulbs in October though in the south it is possible to continue planting in November. In light soils the bulbs may be buried 100 mm (4 in) deep and in normal land put them 75 mm (3 in) down only.
Though the bulbs may be planted so as to almost touch one another (they are often put in this way for the cut flower trade), the gardener will normally have them about 150 mm (6 in) apart. A hole may be made with a dibber at the right depth and the bulbs dropped in. Where numbers are to be planted in a group it is probably quicker to take out a spadeful of soil 75 mm (3 in) deep then place the bulbs underneath in the most ‘natural’ way and put the soil back again, firming it with the back of the spade. Always keep the land clean round about irises.
In the Dwarf Group of irises there are a number of treasures: histroides, a blue purple, white and yellow, which only grows 300 mm (1 ft) high; reticulata, a violet-purple, and /. reticulata Cantab, a light bh both of which are only 150 mm (6 in) high. Then there is /. bracteata, a 150-mm (6-in) yellow and purple, and /. persica, a 50-mm (2-in) white, green-blue and purple orange type. There are others, of course, but these are my favourites. Those I like best in the Dutch irises are Imperator, a violet-blue; Lemon Queen and White Excelsior. In the Spanish irises I can recommend Le Mogol, a bronze; King of the Blues; Canary Bird, a primrose; and Cajanus, a canary yellow. In the English iris group, it is best to buy a mixture.