Q:

What should I do with Hostas planted in heavy clay soil?

My landscaper (I use this term very loosely) planted some hostas in my front yard.  The soil there is very heavy clay and also covered with mulch. Some of the bulbs seem to be doing alright, others are alive but definitely not thriving.  Clearly they should have done something to correct the soil before planting. 
It's there anything I can do now that they have been planted? They've been in the ground about 3 months.
These poor bulbs also get Sun from about 11 to 5 each day.

A:

Hostas are incredibly tough.  One of the few perennials that you can transplant without any shock any time even when they are flowering.
Some varieties are tougher than others but most will take a few years to really get going.
Clay soil is not the optimum condition for them.  As described here

Hostas will grow best in rich organic soil. A loamy soil type may not
  need the addition of organic matter, but few of us are so lucky to
  garden in ideal soil and will need to add organic amendments. The
  recommended soil is well drained, has a slightly acidic pH, and is
  enriched both with nutrients and organic matter.

The amount of light they get (6 hours) is enough and even with the clay soil they should do well if you encourage them. Water regularly during the first year of planting or if your area is experiencing a drought.
The most common problem is slugs who will eat holes in the leaves.  Some varieties with thicker leaves are resistant and sunnier locations are better for this.  If you see this kind of damage consider:

slug bait or copper strips around the hosta
replacing the hosta with a slug resistant variety

