Magnolia dwarf light issue?

[mikecox]

Be very careful about self seeding anything. The wind knows no friends,

Yes, that was my first thought when I read "self-seeding". I think Alyssum is self-seeding as it keeps popping up in our beds after someone planted it on their balcony.

 

[Tetters]

Self seeded plants are sometimes a boon as far as I'm concerned. Not like those plants that multiply like crazy and take over. This particular grass has been no nuisance to me and unwanted seedlings are very easily removed.

I could mention a few nasty ones that really give hassle if you like

 

[Wildflower]

Did the landscaper give you a layout chart of some kind before he started work? When we had ours done they gave us a land survey with the added plants on it so we could ID them later. If they did, you can get a positive ID. If it appears to be a mistake, I'd make it his problem and have him move the plants and replace them with more suitable plants.