Nothing if the soil is like dust.

The conifer will have sucked all the nutrients out of the soil, and the moisture too. It's one of the most difficult places for anything to grow.

Usually nice to put plenty of All purpose compost,and to put small bulbs seasonally-Crocus,Anenemone,snowdrop,small daffodils,tulip.

i've read that euonymus will cope close to conifers but you'd need to dig a fairly big hole,put in plenty of new soil/compost and water it well until it is established.

My mum also has a lonicera " baggesens gold" growing under a large privet hedge and it is thriving but it does get lots of sun for most of the day.