|Hi, I live in zone 5. I have a 6' by 20|
|Hostas grow wonderfully well in Michigan; they grow best in rich, well draining soil in shady garden spots. The planter box you describe will be a perfect growing place for hostas. You can choose any hosta available in your garden center, whether solid green, white edged leaves or even gold edge leaf types. Just choose your favorites.
The sand in the planter box will help the soil drain quickly. Mix the sand and soil together and add some organic matter to make it a rich mixture. You can use compost or peat moss as the organic matter. Mix everything together, then rake it smooth and plant your hostas.
Water as often as necessary to keep the soil moist but not soggy wet. You can allow the top inch of soil to dry out before you water, but when you water be sure to water deeply. This will encourage deep rooting which will keep your hostas happy.
Best wishes with your new hostas!