The Siberian Pea Shrub has finally had volunteers. We've had a lot of rain this fall, and the seeds have sprouted. So when germinating not only do they need to be kept moist, but the temps need to be in the early spring range. Our nights have been in the mid thirties to low 40s. Days have been in the upper 50s to low 60s. We did get a low of 29° a few weeks ago. That may have tricked them into thinking it was spring.
I've saved as much seed from SPS as I could, because I was under the impression that they didn't generally self seed with any consistency. I suspect that mice and other critters eat a lot of the fallen seeds because they lay on the ground for so long. Mine start to drop seed in mid July and don't see any snow coverage til about December. That leaves them exposed for quite a long time to the garden pests.
About how many seedlings have sprouted up in your space versus the total number of seeds that actually went into the soil? I've had really good germination rates when planting in flats but have yet to see a single seedling under either of my shrubs. I always leave a few pods on the shrub to see if it'll self germinate. So far, no luck.