Thanks for writing. If you have good, rich soil, you can plant your lamb's ears a foot or so apart. The better your soil is, the faster they'll grow.
If you want to maintain the silver carpet effect, cut your lamb's ears flower stalks as soon as you see them develop. Don't wait until they rise above the foliage, otherwise you may be left with some hard, stubby stems embedded in the leaves.
---Justin, Senior Garden Editor, BHG.com