One of the most beautiful and carefree silver plants has got to be artemisia, commonly known by its ghastly herbal name of wormwood. Although Artemisia absinthium -- a main ingredient of Absinthe -- has the naughty and probably inaccurate reputation of driving Vincent Van Gogh to madness, the other varieties of this plant are really something every gardener should have, especially for those who might again struggle with drought conditions this summer.
Artemisia ludoviciana, for example, includes the 'Valerie Finnis' cultivar, with beautiful upright, silver-green, tarragon-like foliage. Artemisia schmidtiana is the gorgeous, soft 'Silver Mound' type. Artemisia stelleriana 'Silver Brocade' is pretty much just like the more commonly known Dusty Miller, but fuzzier.
Given too-perfect conditions, like lean soil and lots of sun, some artemisias can take over an area quickly. 'Powis Castle' and the aforementioned 'Valerie Finnis' can be especially aggressive, so trim regularly. Planting in heavy clay soils also seems to keep them in check. Most Artemisias are hardy to USDA Zone 5; some remain evergreen in mild climates. Most varieties are a turn-off for hungry deer and rabbits too.
While exposure to Artemisia may not turn you into a visionary painter, it will certainly bring silvery, hardy beauty to your landscape. Give one a try.