Naturalizing with Spring Bulbs
The effect of a brilliant mass of blossoms is impressive, especially in spring: imagine a sun-flooded hillside splashed with bright yellow daffodils, a lawn covered with the blue haze of tiny squill (Scilla) blossoms, or a streamside dancing with multicolored anemones. Naturalized plantings are easy to create and easy to maintain. Though it takes a few years for the bulbs to multiply and make their full impact, in the meantime you can enjoy the sight of these harbingers of spring. Naturalizing bulbs is a great communal activity: share planting tasks with your gardening neighbors.
Tools and Materials
Choose bulbs for your site and zone. In an open space, you need at least a hundred bulbs to make an impact. To fill smaller nooks or to accent a rock garden requires many fewer.
Make sure to choose bulbs that are suited to your growing conditions: if you live in a northern zone, the varieties must be cold-hardy; in warmer areas, heat tolerance is more crucial if bulbs are to thrive and multiply.
To simplify the process, look for naturalizing mixes or collections. These include varieties well suited to naturalizing.
Generally, full sun in spring and well-drained soil are required. You can plant sun lovers under deciduous trees that will not fully leaf out until after the bulb foliage has faded.
Below are some spring bulbs well suited to naturalizing. All are vigorous growers, and most are resistant to animal and insect pests:
Lay out the planting area. For naturalistic plantings, lay bulbs out in informal masses with curved borders and asymmetrical shapes. Lay a hose or piece of rope on the ground to mark the boundary of your planting area, and plant within it.
Plant the bulbs. Within the marked area, spread out odd numbers of bulbs (three, five, or seven bulbs in a group); even numbers are more formal-looking. Make spacing between groups random, too. Use stakes to mark the areas so you can keep track of where you've planted and where you have yet to plant.
For larger bulbs, use a spade. Plant large bulbs 8 to 12 inches apart within a group, medium bulbs 4 to 6 inches apart. For small bulbs, make holes with a dibble and plant bulbs 3 to 5 inches apart. Cover them with twice their height of soil (so a 2-inch bulb would have 4 inches of soil over its top). Plant deeper in sandy soil, shallower in clay soils.
Dig the spade several inches into the soil, lever the soil clump up, place a bulb in the hole, lower the soil over the bulb, and step on the soil gently to firm it into place. Make another cut with the spade at an odd angle to the first cut, repeating as necessary to complete planting. If you've planted a large area, pull up the marking stake and lay it flat over the planted area so you don't dig there again.
When you're done, place a few stakes around the area, and water so moisture penetrates a couple of inches.
Maintain bulbs. Allow bulb foliage to remain in place until it fades completely, ensuring that the bulbs will have energy to multiply and add more volume to the display every year. Each spring, sprinkle an inch of compost or aged manure over the area.
Over the summer and fall, mow the naturalized bulb bed a few times to remove plants that will compete with bulbs for water and nutrients.
Deciduous trees with deep taproots are better companions for naturalized plantings than trees with shallow, spreading roots.
To naturalize bulbs in your lawn, choose bulbs that blossom and fade before grass grows vigorously and requires mowing: crocus, winter aconite, snowdrops, and scilla.
Photography by Suzanne DeJohn/National Gardening Association