Yard And Garden: Handling Spring-Flowering Bulbs During Fall

 

Fall has arrived in Iowa, but it’s never too early to start thinking about spring flowers. Now is the time to act and prepare for spring-flowering bulbs, be it inside or outside, this fall and winter.

 

Iowa State University Extension and Outreach horticulturists can help answer your questions about spring-flowering bulbs and how to make the most of them this winter. 

 

Tulips, daffodils, hyacinths, crocuses and other spring-flowering bulbs should be planted in early fall (late September to early November. Most spring-flowering bulbs perform best in areas that receive at least 6 hours of direct sun per day. However, snowdrops, snowflakes, and Siberian squill can be successfully grown in partial shade (two to four hours of direct sun). Bulbs also need a well-drained, fertile soil. Poorly-drained soils often can be improved by incorporating organic matter, such as compost or sphagnum peat moss.  

 

Plant spring-flowering bulbs in clusters or groups to achieve the greatest visual impact in the garden.  When planting tulips and daffodils, plant 10 or more bulbs of the same cultivar in an area. Smaller growing plants, such as grape hyacinths and crocuses, should be planted in clusters of 25 or more bulbs.

 

Plant bulbs at a depth equal to three to four times their maximum bulb diameter. Accordingly, tulips and daffodils should be planted 6 to 8 inches deep, crocuses and grape hyacinths only 3 to 4 inches deep. Large bulbs, such as tulips and daffodils, should be spaced 4 to 6 inches apart. A 3-inch-spacing is adequate for crocuses, grape hyacinths and other small bulbs.  

 

After planting, water the bulbs (if the weather in fall is dry) to promote good root development before the onset of winter. 

 

 

To enjoy tulips, daffodils, hyacinths and crocuses indoors during the winter months, the forcing process must begin in early fall. Gardeners need good quality bulbs, a well-drained potting mix and containers with drainage holes in the bottom. Begin by partially filling the container (pot) with potting soil. Then place the bulbs on the soil surface. Adjust the soil level until the tops of the bulbs are even with or slightly below the rim of the container. The number of bulbs to plant per pot depends on the size of the bulb and container.

 

Generally, three hyacinths, three to five daffodils, five to seven tulips, and 10 to 12 crocuses can be planted in a 6-inch-diameter pot. After arranging the bulbs in the pot, place additional potting soil around the bulbs. However, don’t cover the bulbs completely. Allow the tops (noses) of the bulbs to stick above the potting soil. The level of the potting mix should be ½ to 1 inch below the rim of the container. After potting, water each container thoroughly.  

 

In order to bloom, 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. When using the refrigerator for cold storage, place the potted bulbs in a plastic bag if the refrigerator contains apples or other ripening fruit. Ripening fruit give off ethylene gas that may impair flower development. During cold storage, water the bulbs regularly and keep them in complete darkness.  

 

Once the cold requirement has been met, begin to remove the potted bulbs from cold storage. Place the bulbs in a cool (50 to 60 F) location that receives low to medium light. When the bulbs begin to grow, move the plants to a slightly warmer area that receives bright light. Keep the potting soil evenly moist during the forcing period.  Flowering should occur in three to four weeks. For a succession of bloom, remove pots from cold storage at 10 to 14 day intervals.