The Next Generation: Starting PCI Seeds

Kathleen Sayce, August 2018

With fall approaching, Iris seeds are ripening in the Northern Hemisphere, and seed exchanges are getting ready to distribute fresh seeds this coming winter. 

Seeds got away! Use organza bags to hold seeds until you can gather them.

Late summer is a good time to review both well-tested methods to start PCI seeds and known pitfalls that will definitely limit success. 

PCIs have tiny rhizomes and cannot be successfully shipped live around the world; shipping seed is the only way to share this iris group outside the US at this time. 

Pacifica Iris seeds naturally disperse from pods during mid to late summer. When fall rains begin in their natural growing area, those seeds start soaking up moisture, then germinate in winter to early spring. 

Nearly ready to harvest, one more week and the seeds in these Iris douglasiana x I. chrysophylla pods will be ripe and ready to harvest.

If you live on the West Coast of North America in zone 6 or warmer climates, you can put seeds in flats outside and let the weather work on the seeds directly.  Fresh seeds often germinate quickly. Older seeds may need two or three years to decide to grow. Seeds may stay viable for five to seven years. 

If you live elsewhere, where winters are colder, drier, or hotter, then a little creativity is needed. 

Cool wet winter conditions can be replicated by using a refrigerator or toilet tank to provide cold soaking. 

In the fridge, change the water daily. Use small plastic bags for each seed lot, and a small mesh strainer to catch the seeds. Turn them out into the strainer, rinse them under the tap in fresh cold water and also rinse out the bag. Use a spoon to tuck the seeds back into each bag. 

In a toilet tank, seeds go into mesh bags, and regular flushing of the tank provides clean cold water. 

Either way, let the seeds soak for 30 days, then take them out and plant in flats outside.

Pitfalls to avoid include: 

  Use warm water to soak seeds.

  Hold seeds in a location that is too dry. 

  Hold seeds where temperatures stay too warm. 

  Hold seeds where temperatures get too cold—generally colder than zone 6 or 7—but note that some species do well when held under a thick layer of snow over winter. 

  Use a soil mix that is heavy, drains poorly, and or is alkaline.

  Use containers that let roots heat up when sunny. 

Collectively, these iris seeds will decide that too dry, too warm (or hot), too cold, too wet, or too alkaline means ‘do not grow.’

Not shown:  the mesh cover for this flat, which kept the seeds well protected; ten seeds were planted, nine germinated, and eight are thriving.

As seeds germinate, they become tasty snacks for birds and rodents. Protect them! Hardware cloth covers over flats work wonders. 

When I started growing Pacifica Iris from seed, I thought I was getting old seed lots, or had the wrong soil mixtures. Nope, none of that:  I had persistent, sneaky, determined seed thieves, including voles, squirrels, jays and crows. 

All these tips, and more, can be found on SPCNI’s website at pacfiiccoastiris.org.