[gerhoe]

I was intending to grow penstemon plants from seed this coming season. The catalogue notes re the seeds...."sow and then chill for three weeks". It seems an unusual instruction. Does somebody out there know exactly the reason for that instruction ?

[dormouse]

It's called stratification. With some seeds you need to replicate a cold winter spell to help them break dormancy. Chilling them fools them into thinking spring is here when you take them out.