No Spring Perennial Garden is complete without them.
Oriental poppies create one of the big blasts of colors in gardens everywhere. From the basic orange to the fine true reds, whites, and salmons, these are the huge (up to 8 or 9" across) flowers that light up good perennial gardens every year in late spring.
If you don't have perennial poppies, or need more, now's the time. Once they're happy, they're no trouble at all, and last for decades, like peonies. In fact, often in old overgrown gardens, the oriental poppies are the only perennial plants that go right on up through the weeds.
Perennial poppies like rich deep soil. They develop a long tap root, so be sure there's plenty of good soil under each one, and try not to transplant once they're in a good spot. And where? Another big advantage is that they don't demand absolute full sun, although they do appreciate it. Give them full sun or just a little shade, feed them, keep them watered, and after a year or so, you'll have big lush fountains of their jagged foliage every spring, and then an unforgettable burst of perennial flowers just after the tulips and daffodils.