Update on transplanted Iris hartwegii australis

By Kathleen Sayer

Last spring I moved one clump of Iris hartwegii australis (IRHA) to a well insulated planter and placed that planter under the eaves near a hose bib. My intention was to mimic montane thunderstorms in southern California during summer, and in winter to give IRHA some shelter from heavy rain, mimicking snow cover. 

Iris hartwegii australis in flower in its native habitat, the Transverse Ranges of southern California, photo courtesy Richard Richards. 

Richard Richards said this was the wrong time of year to move IRHA, that I should wait for fall. But his words came too late, I had already dug the clump and replanted it. Read about those details here:  https://theamericanirissociety.blogspot.com/2017/05/overcoming-climatean-experiment-with.html from May 2017.

I fully expected to see this plant wither in June and die. Which I would have then reported at some point. A few leaves did die back at the tips, and later browned off. You can see those brown leaves in the image below. 

However, the plant did not die. Instead, new leaf fans started growing in late spring. Then, a couple of weeks ago, several newer fans appeared: 

Recently transplanted Iris hartwegii australis, not yet dead, a new large dark green leaf fan on the left, and tiny newer fans around it. 

Closer in, see three young fans on the left shoot, and one on the right. 

So, this experiment in growing IRHA in a planter is still underway, and has not yet terminated in failure. This IRHA appears to be thriving in its new home!

I grow this plant in a medium sized rectangular styrofoam cooler covered with epoxy cement patch, but have been unhappy with the durability of the epoxy, so am now making hypertufa planters (perlite:coir:cement in 3:1:1 ratio). These should be more durable, and provide a well-aerated cool root-space for Pacifica Iris and other native species that prefer cool roots. Details to follow in a later post. 

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. 

When to Transplant PCIs: Wait for Fall

Kathleen Sayce

Pacific Coast Iris (PCI) can be so touchy to lift and transplant that gardeners may wait years––letting a particularly choice plant increase in size so that half or more of the clump can be left alone, just in case it really doesn't want to be moved. Translate 'doesn't want to be moved' as 'dies' and you have a pretty good idea of the PCI response to conditions or changes in conditions that it doesn't like. PCI aren't easy plants. They are a good challenge to a gardener's skill set, in a rock gardening sort of a way. The payoff is that when they thrive, the flower show is amazing, and unparalleled in the iris world.

Iris tenax x innominata seedlings in their third year. These plants flower weeks later than modern PCI hybrids, extending flowering from early June into early July. Photo by Kathleen Sayce

I have a pale yellow PCI seedling in my garden that I left to grow an additional year, just in case it doesn't take well to being divided and replanted. I'm waiting this spring to see how it responded to being moved last fall. If it survives, no, if it thrives, then I'll be sending plants out to several growers to see how it does in other gardens. It has many marks of a new and desirable hybrid, and the flowers are nicely complex, with a delicate turquoise flush, golden yellow signal and reddish veins, an open and upright flower, a sturdy base of leaves and strong shoots. The current test is to see how it transplants; desirable PCI seedlings often fail at this test.

This seedling PCI last year had lovely flowers with golden signals, reddish veins and a turquoise flush on the falls. This year, I dug it up, divided it, and moved it. Will it thrive? We'll know in a few months. Photo by Kathleen Sayce. 

Choosing when to divide and transplant PCI can be funny to watch from outside the garden. The gardener pulls soil and mulch away from the base of the plant, looks closely, shakes her head, pats the materials back in place, then moves over to check the next plant, then the next... then goes away for a few days or a week. Or two weeks. Or a month. We are looking each time for that clear sign of a growing PCI–-live white roots on the base of the leafy shoots. Live roots grow twice a year, in spring and fall. In cool moist climates, new roots can grow for several months, almost year round, while in climates with prolonged dry summers, they might grow for only a few weeks: 6-8 at most in fall and spring, with cold weather slowing growth midwinter, and dryness slowing growth midsummer.

Fall is a good time to transplant PCI. These plants have sturdy shoots with white roots on the current year's fan. The new fans are visible as tiny sprouts above the roots, on the left side of both transplants. These transplants are from a vigorous yellow-flowered I. douglasiana selection. Photo by Kathleen Sayce

Why this spring and fall root growth pattern? PCI are native to the West Coast of North America, which has a Mediterranean-type climate. This means that there is a brief to very prolonged dry season each summer, depending on latitude, when PCI go summer dormant. When rains return in the fall, they produce tiny new fans of leaves with tiny buds of roots; and older roots just behind them, on the current year's fan, start growing again. The new fans elongate in late winter and spring, and shoots emerge to bloom in early spring to early summer, depending on latitude and climate. In late spring to summer, PCI set seed, and go dormant for the balance of the summer season. They awaken in fall with the onset of cooler temperatures and rain, producing new roots and tiny new fans.

Nurseries know this, and depending on where each is located, aim to ship plants when their roots are growing strongly. This is most often in the fall. For gardeners accustomed to shopping for new flowers by seeing flowering plants at a nursery, and taking them home, this delay can be frustratingly long.

Patience is everything in a garden. Growing PCI is a study in patience. You see the plant. You find a nursery that sells that plant, and place an order. You wait. That fall, or the next, it arrives, and you plant it, and you wait. Perhaps it dies––these are PCI we are discussing, after all. So you try again. When it flowers, you see that it's the plant you sought. Or not. And you try again.  But what a reward with success.