Don’t you just HATE those iris varieties that grow “like weeds”?!! It seems that they are forever needing transplanting. If you transplant every other year (all that work!) you only get really good bloom once every two years. Not fair!
I first visited Evelyn Kegerise’s garden in Temple, Pennsylvania in the mid l980's. It was filled with bloom from border to border and I was told by many others that every year you could expect this massive display of bloom. (On two subsequent visits I found that her bloom was consistently impressive. ) As I became more acquainted with Evelyn she became a treasure trove of information about culture and hybridizing to a neophyte like myself..
I learned that she rarely lifted iris clumps en masse and transplanted; she practiced “thinning” as often as she found time during the summer months. She explained that it could be performed in time intervals between more pressing garden tasks and was not nearly as physically demanding as lifting, cleaning, trimming and re-planting an entire clump.
Long-time friend and iris grower Rachel Drumm of Stillwater, Oklahoma has recently relocated to smaller living quarters and gifted me with her collection of AIS Bulletins dating back to the 1940's. Each of these early issues are filled with member letters, comments and questions – a long-forgotten idea which should be re-activated. (Virtually every RVP in each AIS region was responsible for submitting extensive garden visit and bloom reports, making for nation-wide reporting of PERFORMING iris varieties across the country.)
Many of these members’ queries served to provide valuable information that the typical non-innovative “experts” seem never to offer. It is more than sad that current iris society publications have become boring reports of committees, meetings and bureaucratic proclamations, ad nauseam. The text that follows was a reply to a query from “R. C., New York” which appeared in the July, 1949, issue #414, lamenting that when he re-set iris varieties that the bloom the following spring was very scant. The response is provided by Editor Sam Caldwell.
Garden plantings which are maintained over a number of years do require periodic renovation, and it is not unusual to have below par bloom in many perennials in addition to irises the next year after their roots have been disturbed. To keep up a good display every year at the well known Presby Gardens in Montclair, N. J., a “staggered” system of replanting is employed; that is, part of the beds are renewed annually. Enough plants are always at or near enough to their peak performance state to make up for the lighter bloom on the ones that have been recently reset.
A scheme for keeping iris plantings in good flowering condition for many years has been suggested by Dr. G. Alan Kriz, Elm Grove, Wisconsin. It is a sensible and simple method–well worth a trial. Here is what the Doctor says:
“When I took up iris growing as a hobby in l935 it was partly because of the flower’s appeal but largely because of easy culture. A plant that could be set and and thrive, come snows or droughts, and bring forth an annual harvest of bloom was the answer to a gardener’s dream. I soon learned that large flowers required somewhat more than squatters’ rights. Transplanting every other year into new soil became an increasing chore as my collection grew. Transplanting had the drawback the first year after moving-- bloom was sub-standard in amount and size. If one waited four or five years, crowding of rhizomes would limit perfection of bloom by exhausting the soil nutrients, steadily reducing the size of rhizome and flower. It appeared that a major operation was necessary every two or three years to maintain an iris garden at peak form.
In casting about for a way to maintain a large garden with minimum effort, I began RHIZOME CUTTING. Instead of lifting the whole clump at transplanting time, I would dissect the network with a sharp knife so as to remove most of the smaller rhizomes. These were lifted in a manner so as not to disturb the few larger rhizomes which I chose to leave. This practice insured annual bloom from my favorite varieties. I considered it to be a minor surgical procedure which warranted less shock to the subject. Depending on the age and size of the clump, I would remove one-fourth to three-fourths of the mass. The better rhizomes are dissected from these lifted portions for replanting as desired. Another advantage of this method is the removal of dead rhizomes which act as a focus for iris rot.
We know from the anatomy of the iris that the original rhizome A (see drawing) furnishes the bloom stalks F and usually at least 2 offshoots, B and C. The rhizome A exhausts itself in the process and dies at the end of the season. The dead rhizome remains to decay. Decaying vegetation is a nidus for rot, worms and insects. A few sharp cuts through the sections marked X are a simple operation in the spring shortly after growth starts. At this time the living and dead portions can readily be distinguished. Stems and all parts showing poor growth or crowding may be cut away with a sharp knife. Please note that old matted clumps with grandpappies, uncles, aunts and little sissies all huddled together and sitting on each other’s laps would certainly need radical surgery but preferably should be lifted and divided. (Italics added.)
Gaps and depressions left by removal of exhausted and unwanted rhizomes will leave room for a top dressing. This can be in the form of loose soil, sandy loam or compost. I prefer the latter mixed with one-third coarse sand. A sprinkle of bone meal may be added at this time if desired. The soil is replenished and the rhizomes given room to develop, all without disturbing roots or checking growth and bloom.
A final note: Dr. Kriz does not seem to have made any further contributions to future issues of the AIS Bulletin under this editor. Being such a clever gardener with a clear gift of communication, it is difficult not to wonder if he was invited and encouraged to make further contributions to the publication. What simple and unheralded techniques do you use in your iris garden that might be of great interest and assistance to iris growers in the 21st century?