The best time to plant spring bulbs depends on where you live. Ideally, wait until the soil temperature is below 60°F. As a general guide, plant in September through early October if you live in USDA Hardiness Zones 4 or 5; October to early November in zones 6 or 7; and November to early December in zones 8 and 9. In mild winter regions, you can give the bulbs their required cold treatment by placing them in the refrigerator for 8 to 10 weeks in the fall. Then plant them in late December to early January.
Plant a variety of bulbs to extend the flowering season. In addition to daffodils and tulips, include some early-flowering bulbs – such as grape hyacinths, crocuses, snowdrops and scilla – to herald the start of spring. Late-flowering alliums will continue the show into early summer.
Pick a Site. Most bulb species prefer well-drained – not soggy – soil, and a location with at least 6 hours of sun a day during spring through summer. Determine light levels in summer when the trees have leafed out, and make sure the bulbs will not be in the shade when the leaves still need the sun to make energy for next year’s flowers.
Dig Holes. Digging up the whole bed makes bulb spacing, layering and soil amending easier. The depth of the hole should equal three to four times the bulb height. For example, if a daffodil bulb is 3 inches tall, plant so its base is 9 to 12 inches down. In heavier clay soils, plant 9 inches deep; in lighter, sandier soils, plant 12 inches deep. Space bulbs according to the supplier’s recommendations.
Arrange bulbs. Set the bulbs in a planting bed or in separate planting holes with their roots or basal plate downward. If you can’t tell which way is up, lay the bulb on its side. Fill the planting hole with soil and firm it gently.
Water and mulch. Water the bulbs right after planting to help initiate growth. In mild-winter areas, mulch right after planting to help keep soil cool and moist. Apply mulch after soil freezes in cold-winter areas.
Fertilize. Bulbs need fertilizer, but the kind of nutrition varies with the plant. Tulips, hyacinths and fritillaria are best served by a 9-9-6 formula fertilizer. Daffodils and snowdrops need nitrogen and potassium and thrive on a 5-10-20 mixture. For both fertilizers, use about 1/2 cup per 10 square feet. Sprinkle it on top of the soil after planting, not in the hole. Fertilizer in the hole may burn tender young roots.
Fertilize established bulb beds in fall, too. All the foliage is dormant then, so it may be difficult to locate bulb beds, especially if they’re naturalized. Try planting grape hyacinths (Muscari armeniacum) as indicator bulbs. They produce small blue flowers in the spring but also send up fall foliage. Plant them around the edge of the bulb area.
A former floral designer and interior plantscaper, Kathie Bond-Borie has spent 20 years as a garden writer/editor, including her current role as Horticultural Editor for the National Gardening Association. She loves designing with plants, and spends more time playing in the garden – planting and trying new combinations – than sitting and appreciating it.
For more tips and garden information visit www.garden.org.
National Gardening Association