Check roots to know when to transplant Pacifica Iris

February 26, 2017 

Kathleen Sayce

The West Coast is having a winter of pronounced weather, if one thinks of a series of Atmospheric Rivers (AR) as ‘pronounced’. I know I do—no soft drizzling days here, no ma'am. ARs are firehoses in the sky, huge rivers of moisture that deliver strong winds and warm rains from the Equator to higher latitudes. 

Above latitude 46 on the ocean, where I garden, rainfall is well above average for the water year, which began October 1st. Other areas are also above, including much of California, which is experiencing a definite wet season in an otherwise years-long drought. Those warm storms alternate with days of clear skies, balmy temperatures, and weeks of more typical winter weather, including snow, hail and much colder rain. 

Pacifica Iris clump with a little hail topdressing:  yes, this plant has active root growth below ground. 

This seesawing back and forth leads me to wonder what is going on below ground and when will be a good time to transplant irises, including Pacifica Iris. There is only one time to transplant them, and that is when plants are in active root growth. 

Healthy PCI buds suggest it's time to divide and replant--but check the roots first to ensure success. 

This means you have to gently scrape out the soil under the new buds and check the roots. Normally this is in the fall after rains begin, following dry summers, or winter into spring, before the annual summer drought begins. 

PCI 'Mission Santa Cruz' has a lovely new root, and is ready to be moved. 

Another general rule is that while Pacifica Iris are flowering and ripening seeds, they can be transplanted. I’d like to know how widely this works, so if you have experience with transplanting during spring, please let me know, or add a comment here at the bottom. 

If you live in other climate areas and grow Pacifica Iris, begin by checking roots on the plants you want to divide, repot or transplant.

Between hail storms today I went out and dug around a few plants to see what they are doing in the soil. I found a mixed bag, ranging from completely dormant (Iris tenax) to starting to grow (several recent Ghio hybrids). 

This PCI fan shows the roots from young (and active) on the left through the full sequence of older darker roots to fine roots off the rhizome on the right. It's ready to be replanted. 

I’ve mentioned before that hybrids from the Bay Area in California flower too early in my garden to escape heavy rain, and thus rarely set seed. If the rain is so hard that flowers are battered, bees aren’t flying around either.  These irises also begin growing very early—perhaps they are more attuned to day length than temperature. 

The finding in late February in my garden was that some new roots are starting to elongate just behind the new fans in some plants. There aren’t very many yet, one root per fan so far, where there will be four or more in a few weeks, but that’s enough of a sign of new growth that those early flowering hybrids can be dug up, divided, and replanted. 

Iris tenax is just starting to break winter dormancy; you can see the green shoots to the upper right. Roots are still brown. 

I will wait a few weeks for the others. Iris tenax, I. thompsonii, I. innominata and their various hybrids are still largely dormant, with few signs of new leaves on the first, and only a few new shoots on the latter.

Iris lazica has a bud. Not a PCI, but a good companion to them, and one that adds months of flowers to the garden, as does I. unguicularis. 

For comparison, in southern California, PCI are in active growth and starting to flower. Meanwhile, Iris lazica has put up a first bud, along with PCI ‘Premontion of Spring’, which has been flowering off and on since last September, as has Iris unguicularis. 

The next time you look at your Pacific Iris plants and wonder about getting starting dividing, go check the roots first. It’s the best way to ensure success.