Conifer?
By Baffledbill
Lanarkshire,
United Kingdom 
Hi folks. Today I decided to trim back a Rosemary plant which had been neglected and was very 'spindly' it was around 24 inches in height before I took it right back. Behind it I discovered what very much looks like a young Conifer growing. Is it possible Conifers appear in your garden without actually planting one? I will add a photo of it tomorrow as my camera was down today.
Photo added as promised. If that is indeed a Conifer then strangely enough it appears a Heather has started to grow there as well.
26 Jul, 2020
Answers
oh yes I get lots of seedlings and I am sure if I didn't weed them out they would grow quite happily.
as Tug says many have winged, light, wind dispersed seeds.
27 Jul, 2020
Thank you both. I will post a picture as soon as I can take one, it has rained here in Glasgow heavily all day. I think there is a heather plant growing right next to it as well. Weird.
27 Jul, 2020
I get loads of this conifer and always pull them off. yes it looks like a heather and could have come in peat based compost.
27 Jul, 2020
Junipers and yews have berries that birds will eat. Pines, spruces, firs, Douglas firs, larches, and hemlocks all have winged seeds that can fly on the wind. Cypress kin--Chamaecyparis, xCuprocyparis, Cupressus, Thuja, and Platycladus--have salt grain sized seed that can be shaken as much as 30 meters away from the parent tree.
So, not impossible, though somewhat less common than certain other volunteers.
27 Jul, 2020