If they don't rot from possibly staying wet, I suppose they can.

It's not a good media for starting seeds though.

 I've done that a lot  

Howard

 Then how doI  get good results

    Every  9out of 10  it works for me  so thinking they won't  come  up in clay soil   I grew up growing every thing in clay but if you watch what you are doing  it can be a great  medium  for starting out

what the point of the title..

i would start seeds in pots. in proper media.. in spring...

and by fall.. be prepared to move them to mother earth presuming i did not want to deal with potted trees in winter.. but that might be a function of where you are.. and how hard it will be.. like in my ground freeze mi ...

being able to fully manipulate all plant culture variables.. for the first few months of life.. would make it so much easier..

and then.. bare root them.. and properly plant them in mother earth.. and you should have a high success rate..

clay soil is the bases of ALL ball and burlap plants sold on the face of the earth.. there is nothing inherently wrong with clay soils.. you just have to learn how to deal with the drainage issues.. or lack of drainage... and thats not all that hard...

also..you can let is go so dry in mid summer that it cracks.. because you will have a hard time rehydrating the soil down where the roots are...

ken

 I always  had clay soil   to use and I dowell  with it

Me 2

  Seeds normally aren't  too picky what type of soil they are grown in . Sioless mixes  have  been my on doing  for  I have always had  trouble with  them .  But I know how to grow things iclay  dirts from experience  even though  my horticultural training tried to teach me other wise but they failed    my family on both sides were  farmers  so growing things in clay. Was  bred   into me

Howard

 I just learned to master the clay soil instead of fighting it I learned to work with it  for me it came easily