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What is a Bulb? Daffodils, tulips and more!

15 Nov 2019 12:00 AM | Brenda Peshak

Daffodils in the Bulb Bed at Demonstration Garden

Many varieties of Daffodil can be found at Demonstration Garden in April and early May.

What is a bulb?

What is a bulb? It’s a rounded underground storage unit consisting of a short stem surrounded by scales that feed and protect the growing point. Picture an onion. Not all bulbs are the same shape and size as an onion, but the most common and popular bulbs look and grow pretty much the same as an onion. 

Bulbs hardy in Iowa include daffodil, tulip, lily, crocus, snowdrop, and hyacinth. 

Spring Flowering Bulbs

Plant spring-flowering bulbs in fall from late September up until the soil freezes. Be sure to plant the pointed end up and the larger end down. The roots grow from the base of the bulb–the basal plate. If uncertain, place the bulb on its side. It knows which way is up! (Again, picture an onion. The base is where roots emerge.)

Summer Flowering Bulbs

Plant summer and fall-blooming bulbs in the spring as soon as the soil temperature (not the air temperature) reaches a minimum of 60 degrees. Popular summer bloomers include anemone, begonia, caladium, calla lily, canna, elephant ear, gladioli, and tuberose. Because these are not winter-hardy in Iowa, they must be dug up in the fall and stored in cool (but not freezing) temperatures.

Fall Flowering Bulbs

Fall-bloomers include some varieties of crocus and cyclamen. These are winter-hardy and don’t need to be stored inside.

Bulb Planting and Maintenance tips:

  1. Light: Choose a site with a minimum of four hours of sun. Six is better, but avoid hot, dry locations suitable for cactus!
  2. Location: Nearly all bulbs require excellent drainage. They will rot in soggy soil. If your soil is poorly drained, either consider another site, aerate the soil with perlite or coarse sand, or plant in a raised bed.
  3. Depth: Dig a hole between two and a half or three times the height of the bulb and place the base of the bulb at the bottom of the hole.
  4. Spacing: Bulbs multiply, so allow adequate space between them. The larger the bulb, the more space is required. For daffodils, four or six inches. For crocus, two or three inches.
  5. Feeding: Apply fertilizer labeled as “bulb food” during planting. Mix fertilizer in with the soil, with a shallow layer of soil between the bulb and the soil-fertilizer mix. Follow package directions! Too much fertilizer will burn the roots, so more is NOT better. The following year, top-dress with fertilizer and work into the soil.
  6. After blooming: DO NOT cut green foliage unless you plan to discard the bulbs. Foliage provides food to the bulb—and ensures a good show next year. Wait until foliage has turned yellow and starts to droop.
  7. Maintenance: Keep the area free of weeds with an organic mulch.

Bulbs at Demonstration Garden

Demonstration Garden bulb display features a wide variety of  bulbs, tubers, and corms:

  • Allium ‘Persian blue’
  • Cannas 
  • Daffodils (assorted varieties)
  • Dahlias
  • Daylily (mixed colors)
  • Elephant Ear
  • Irises (mixed varieties) – Bearded Iris ‘Burgundy Party‘ and ‘Batik’
  • Lilies: Day Lily, Surprise Lily, Casablanca and Oriental ‘Starfighter’
  • Spanish Bluebells
  • Starflowers (blue and white)

Gardening in the Zone: Spring Flowering Bulbs

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