AMES, Iowa-- Daffodils are a welcome sign of spring. To enjoy their beauty, gardeners must plant daffodils in the fall. There are several thousand daffodil varieties (cultivars), but standard planting practices. Horticulturists with Iowa State University Extension and Outreach answer questions about planting daffodils and forcing blooms indoors. The horticulturists are available to answer gardening questions by email at email@example.com and by phone at 515-294-3108.
October is the ideal time to plant daffodils, tulips and other spring-flowering bulbs in Iowa. When planted in October, spring-flowering bulbs have time to develop a good root system before the ground freezes in winter. If the weather permits (the ground isn’t frozen), bulbs can be planted as late as late November and early December.
Daffodils perform best in partial to full sun. Planting sites should receive at least six hours of direct sun per day. Daffodils will gradually decline in vigor and won’t bloom well in shady locations. Daffodils also need a well-drained, fertile soil. Bulbs may rot in wet, poorly drained sites.
Plant spring-flowering bulbs at a depth equal to three to four times their maximum bulb diameter. Accordingly, daffodils and tulips should be planted 6 to 8 inches deep, crocuses and grape hyacinths 3 to 4 inches deep. Large bulbs, such as daffodils and tulips, should be spaced 6 inches apart. A 3-inch spacing is adequate for crocuses, grape hyacinths and other small bulbs.
To successfully force daffodils indoors, you’ll need high quality bulbs, a well-drained commercial potting mix and suitable containers. Containers for forcing can be plastic, clay, ceramic or metal. Almost any container can be used as long as it has drainage holes in the bottom.
Begin by partially filling the container with potting soil. Then place the daffodil bulbs on the soil surface. Adjust the soil level until the tops of the bulbs are even or slightly below the rim of the container. The number of bulbs to plant per pot depends on the size of the bulbs and the container. Typically, three to five bulbs are appropriate for a 6-inch-diameter pot. However, a 6-inch pot will usually accommodate five to seven bulbs of miniature cultivars. Once the bulbs are properly positioned, place additional potting soil around the bulbs. However, do not completely cover the bulbs. Allow the bulb tops (noses) to stick above the potting soil. For ease of watering, the level of the soil mix should be ½ to 1 inch below the rim of the container. Label each container as it is planted. Include the name of the cultivar and the planting date. After potting, water each container thoroughly.
In order to bloom, daffodils and other spring-flowering bulbs must be exposed to temperatures of 40 to 45 degrees Fahrenheit for 12 to 16 weeks. Possible storage sites include the refrigerator, root cellar or an outdoor trench. During cold storage, water the bulbs regularly and keep them in complete darkness.
Begin to remove the potted daffodil bulbs from cold storage once the cold requirement has been met. At this time, yellow shoots should have begun to emerge from the bulbs. Place the daffodils in a cool (50 to 60 F) location that receives low to medium light. Leave them in this area until the shoots turn green, usually four or five days. Then move the daffodils to a brightly lit, 60 to 70 F location. Keep the plants well watered. Turn the containers regularly to promote straight, upright growth. On average, flowering should occur three to four weeks after the bulbs have been removed from cold storage. For a succession of bloom indoors, remove pots from cold storage every two weeks.