I found a comment on the Pacific Bulb Society site that while a seed may begin to sprout this year (after a couple of months to germinate), it still needs a winter before it begins to grow. Sounds like it might be faster to divide bulbs as it has very few variations.

in the past I have just pulled the berries off and planted them next to the parent plants.Some germinate and grow well others seem to disappear. they are one of my favourite plants.

Thanks Wylie, maybe just a case for popping the seeds in an old pot with some compost & leaving them in a neglected corner? Anything to avoid opening my wallet😄
Winter won't be a problem here in Manchester UK...

Any particular cautions re: toxicity Seaburn? I was thinking of using rubber gloves to extract the seeds & let them dry, maybe just squishing & sowing would be better

I just pulled them off and planted them straight in the soil, flesh and all. mother nature did the rest.

yes it is toxic if eaten and can cause serious disruption of heart function. but I don't suppose you plan on eating it. the sap shouldn't be problem, but wear gloves if at all worried. the flower stems/sap are ok, they were in my wedding bouquet and headdress [36 yrs ago].

Ah nice, I can see how they'd suit a wedding.
I'll get some gloves & press them in under the bushes, never one to turn down an easy method 😊

They do spread naturally when they are happy.

I was recently at an event and they had Lily of the Valley in pots (along with other flowers) on all the dinner tables! I had no idea they were so poisonous at the time, and neither (presumably) did the event organizers...

I'll have to give the buddleias a fairly drastic topping after they flower this year but will still have a nice dappled shade corner for them Stera.
Another thing I was planning was to put down a leafy mulch from some nearby plane trees late Autumn to benefit the fern & Aconites, etc. So that should help the lily of the valley settle & spread.
Does planning now for Autumn mean I've got the bug quite badly😊