I don't know what you mean by 'Drift' possibly a rooted runner of something? Anyway, most things are best moved in Autumn, the top part of the plant is dormant, but there will probably be root growth to help it establish before spring when the top takes off again.
When planting out remember to knock a bit of soil off the plant into the hole to mix in, sometimes roots have problems making the jump from the pot soil to the garden soil, mixing the soil and disturbing the roots a bit if it is pot bound helps stop that. I was once asked to dig out a plant that was 'useless and doing nothing since I planted it two years ago', and found a solid root system the shape of the original pot. Another thing I often do is give the plant half a turn in each direction before I firm it in.