You can plant both in clay by amending the soil with compost. Till sacks of compost in with a rototiller for large areas or a shovel for smaller areas. If you are transplanting from a nursery container dig a hole three times as wide as the container and just as deep. Mix that soil with compost on a ratio of three parts soil to one part compost. If you can afford to buy a sack of worm castings throw in a shovel full of that to the mix. Be sure to plant the shrub/tree at the same depth it was in in the pot! Tamp the soil in well and water to settle the plant in the hole.