You should be fine. The wicker will shade the plastic & help keep the planting cool. I've seen many wicker baskets designed for planting that come already lined with plastic when you buy them. You can use them as a cache pot, as is, or poke drainage holes in the bottom and plant in them directly.

Al

I like to use wicker baskets as planters... I usually use the smaller white waste basket sized garbage bags as liners, with holes poked in the bottom for drainage... I've never had a problem doing it that way... I've also lined some larger wicker baskets with black plastic garbage bags, and haven't had a problem with those, either.

Once a basket begins to fall apart somewhat, I plant a perennial directly in it, without a liner, and place it somewhere out in the garden for a country look... as time goes by, the wicker breaks down and the plant sends roots right through the bottom and into the garden soil... in the meantime, it makes for an interesting bit of garden art with a cottage garden feel!