Planting bulbs for naturalizing doesn't vary much from planting bulbs elsewhere except that you'll be working around other elements—turf, roots, existing plants.
The terrain. If your site is riddled with tree roots, it's a good idea to stick to small bulbs that don't have to be planted more than 2 to 4 inches deep. These include the smaller ornamental onions (Allium spp.), anemones, snowflakes, glories-of-the-snow, crocuses, winter aconites, dog's-tooth violets (Erythronium spp.), snowdrops, striped squill, scillas, grape hyacinths, Spanish bluebells, and crocosmias.
When planting bulbs in a lawn, there are two ways to proceed. One is to peel off the turf with a flat-edged spade and then plant underneath. As long as the turf is not allowed to dry out completely, it will reestablish itself.
The other way is to punch holes in the turf and plant bulbs individually. This disturbs the turf less but can make planting more difficult since you have to hack through grass.
Feeding. It's always a good idea to work in some compost at planting time if possible, but bulbs suited to spreading should be able to cope with the existing soil on their own. Still, the looser the soil the better, so if it's easy to add compost, do it.
Ferguson advises against adding bonemeal. This animal by-product is now processed differently than it was decades ago, and the new process removes many of the nutrients valuable for bulbs. Besides, bonemeal can attract wildlife that will dig up or devour the bulbs.
Planting. Generally, you need to plant bulbs, in shade or full sun, before your area's first hard frost— September, October, or November in most areas north of the Mason-Dixon line and below the line as far south as Georgia and Arizona and in the Pacific Northwest. Further south, plant in the shade in October, November or December. Well-drained soil is the crucial factor, along with choosing bulbs appropriate for your area for naturalizing. Find sites for them that showcase their wild charms, and enjoy a spring-after-spring celebration of natural gardening at its colorful best.
Wherever you decide to plant your bulbs, the experts agree that it's important to get the best bang for your buck by planting en masse. "You want enough of a concentration that it's showy," Cornwell says. With small bulbs, he recommends planting at least 50; with larger bulbs, a couple dozen. Mail order companies often offer discounts on bulbs ordered in large quantities.
And no planting in soldier-straight rows, either. This is naturalizing, after all. Plant in large, tapering drifts. Or simply toss the bulbs on the ground and plant them where they land.
The best thing is, once established, naturalized bulbs completely fend for themselves. "These are no-care plantings," says Kunst. And the rewards of your effort will pay off for decades. "Plant bulbs in the right spot and they'll spread into ever-widening pools of beauty."