Exactly, Poly. Everyone is growing their Iris differently & in a variety of conditions, yet, maybe some are doing it fairly similarly.
I've received Iris rhizomes, that had their roots- -trimmed- -to about four inches in length...
Had they not been cut, they most likely would, or could have been much longer. Simply giving a brief spray with the hose, occasionally , is going to cause that Iris to grow roots, mainly near the surface, simply because of using the same repeated, watering technique.
If your summer is a "dry" one, or you do not receive adequate, deep, frequently regular precipitation then you may expect the same. If you do not water adequately, deeply enough, & often enough, to get those deeply grown roots, you are unlikely to ever get them to grow in that fashion, as Poly gave you an example of, above. Just like. when planted in a deep pot, watered regularly, in a good soil mix, & watered deeply.
Unless, your garden soil has inadequate & poor drainage entirely, it may not be such a good idea, or your precipitation in summer , is rather to the extreme. Or worse yet, a combination of both...
I've had a rather great variety of plants, through a variety of mail order sources, purchased at garden centers, big box stores, - you name it ! This has been over many years time, & some vendors had extremely different growing techniques. Some, varied, form my own. But, while you tend to be 'thinking" the roots may only stay near the surface & treat it that way, that is about exactly the results that you are going get.
While deeply watering, in deeply amended, well draining soil may give an entirely different results.
So, I will pose this question. Why else then, would some people go to such great lengths, to get such a deeply, "properly, well dug" & amended bed , for Tall Bearded Iris ?
