Last fall, I planted rhizomes of tall bearded iris (eight varieties). I planted the rhizomes shallowly, with the tops just under the surface of the soil. This spring, DH and I mulched the entire garden, about 2" deep, using a locally-made composted bark mulch. Since the rhizomes were at the same level as the rest of the soil, they got covered. I'm sure that this was a mistake.
Some of the irises bloomed. Others look poor. I fertilized, in early spring, with a sprinkling of 20-20-20. Last week, I fertilized, with a slurry of superphosphate and dissolved potassium chloride.
Yesterday, I dug down to the level of the rhizomes, uncovering the tops to the sun (as advised by several iris mavens). Although most of the rhizomes looked OK, one had a mushy section.
My town has damp winters and dry summers. Total annual rainfall is only 15" or so. The temperature seldom rises above 70°F in summer (it's been about
62°F or so, for the past few weeks). The winters are mild (temperature seldom drops below 25°F, usually in the low 40s during the day).
Questions:
- Should I lift the plants now, to reset them at ground level? Or should I leave them in their dug-down "pits" until later in the year? Between soil subsidence and the mulch layer, the holes to the rhizomes are 3" deep. When should I dig them? Should I dig out the mushy rhizome now, or leave it till later?
- Should I plant them above the ground level, for drainage? Due to the low rainfall, drought-tolerant plants are more used, in this area. I'm afraid that raising the irises will make them more vulnerable to drought.
- The weakest plant, which has just a tiny leaf that is practically dead, has a healthy-looking rhizome (only 2" across, but firm). Now that it is uncovered, it appears to be making new, little fans from a couple of eyes on the surface. Is this normal? Should I leave this one in place, even if I move the others?
Any further advice?
Wendy Sequim, WA (Zone 8)