Yard and garden: Planting spring-blooming blubs

Iowa State University Extension
Fall is a great time to plant the appropriate bulbs for spring color.

Autumn is a time of beautiful colors. Trees turn vibrant yellows and red and pumpkins ripen to deep orange.

Fall is also a time to think about the colors of spring. The many beautiful spring-blooming bulbs like tulips, daffodil and squill, all grow and flower in spring but must be planted in the fall. A little planning, planting and care in the fall will reap colorful rewards in the spring, according to horticulture specialists with Iowa State University Extension and Outreach.

How do I purchase high-quality blubs?

When buying bulbs, select only firm, solid bulbs for planting. Avoid bulbs that are shriveled or lightweight. Bulbs that are discolored by mold or that contain soft spots should also be avoided.

Size matters when selecting bulbs. The bigger the bulb the better the flower display. Smaller bulbs often bloom but you get more bang for your buck with the larger bulbs.

Bulbs can be purchased from garden centers, greenhouses, nurseries, big box stores and many online retailers. These plants have the advantage of transporting and shipping easily, making mail order sources great options, especially to find unusual or hard-to-find species and cultivars.

When do I plant spring-blooming bulbs?

October is the ideal time to plant spring-flowering bulbs in Iowa. This allows bulbs to establish and develop good roots before winter. Planting bulbs too early in the season in September when soil temperatures have not yet cooled may cause some bulbs like tulips to emerge in the fall. Procrastinators can plant spring-flowering bulbs as late as December if the ground remains unfrozen.

Where should I plant spring-blooming bulbs?

Most bulbs should be planted in a full or part-sun location. Early blooming bulbs are often successful beneath a high branched deciduous tree because they usually flower before the tree fully leafs out. After the bulbs have finished flowering, many can tolerate the light shade from trees.

Nearly all bulbs require well-drained soils. Poorly drained or wet soils often cause decline and rot,making them short-lived in the garden. Amend poor soils before planting by incorporating organic matter, such as compost or peat. 

Plant spring-flowering bulbs in clusters or groups to achieve the greatest visual impact in the garden. When planting large bulbs, such as daffodils or tulips, plant five or more bulbs of the same variety in an area. Smaller growing plants, such as grape hyacinths and crocuses, should be planted in drifts of 25 or more bulbs. Bulbs planted alone or in rows do not look as good in the garden as large sweeps or drifts of color. For a naturalized look, simply toss handfuls of bulbs in the garden and plant them where they land. Consider planting them with ornamental grasses, hosta, daylily, and other perennials that will grow up later in the season and hide the foliage of the bulbs as it yellows. Select a location where their early blooms can be seen and appreciated such as along commonly used walkways or near the front door. Bulbs with different bloom times can be mixed together for a long-lasting display.

How do I plant spring-blooming bulbs?

Plant bulbs at a depth equal to two or three times their maximum bulb diameter. Larger bulbs like tulips, daffodils and hyacinths are often planted 6-8 inches deep. The smaller bulbs like squill, snowdrops and crocus are often planted 3 to 4 inches deep. Larger bulbs can be spaced 4-6 inches apart while a 2-3 inch spacing is more suitable for the smaller bulbs.

Set bulbs in the ground with the pointed end up. For some bulbs or bulb-like structures it can be difficult to tell which end goes up. If no roots or buds are apparent, you can plant some bulbs on their sides. The bulb will find the sun and bloom normally with only a little extra effort.

Bulb planters, trowels and auger attachments for electric drills are available to assist the gardener in bulb planting. For a mass planting of bulbs, remove the soil in the entire planting area to the proper depth with a shovel. Place the bulbs in the desired arrangement or pattern and then carefully backfill with soil.

While not typically necessary, fertilizers like 5-10-5, Bulb Booster or Bone Meal can be incorporated into the soil at the time of planting. Bone meal is often slower acting and more expensive than the other fertilizers. These fertilizers are more important for the development of next year's bulb than they are for the upcoming spring flowers.

Water the areas after planting to help settle soil in around the bulbs and provide plenty of moisture for root growth, especially if soils are dry. Avoid overwatering as most bulbs do not tolerate wet conditions well.