All good gardeners know that the best time to set out new varieties of German iris or to divide established clumps is in June, immediately after they bloom.
However, most of us are usually absorbed in a hundred and one more pressing tasks at that time, and often iris does not get the attention it needs till mid-summer.
As with all perennials, well-prepared soil to a depth of 10” inches or more that has been enriched with some form of organic matter is the ideal medium for planting the iris.
Planting The Iris
Importance Of Drainage
Drainage is of prime importance, and thorough watering is essential during dry periods after planting.
Most iris varieties are vigorous growers and should be spaced at least 10” or I2” inches apart if grown in beds by themselves.
If they are being mixed with other perennials, more space should be allowed for each division.
Planting Good Varieties
When planting, bear in mind that, for best results, clumps should be reset every three years.
Hybridizers, amateurs, and professionals have produced an extraordinary collection of good varieties, many of which are comparatively inexpensive.
The Popularity Poll of the American Iris Society, which appeared in the June 1953 issue of Horticulture, page 264, may well serve as a guide to all who plant new irises now for bloom in next year’s garden.
Dividing The Plants
Care should be taken in dividing the iris clumps to get the greatest number of divisions from a choice variety, as shown in the sketches below.
- Most desirable division,
- Divisions are less likely to bloom the first year after planting.
- A worthless portion of rhizome that should be discarded.
Steps In Planting Iris
- Established clumps should be divided into single portions. Select only the healthy rhizomes from the outer edge of the clump.
- In cutting divisions, remove old growth, trim roots when necessary, and cut foliage fan-shaped, as shown in the sketch.
- Avoid deep planting and choose a well-drained location. Firm soil around rhizomes.
- A plant set deeper than desirable. This often causes the decay of rhizomes, especially in wet weather.
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