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Spring-Flowering Bulbs: A Primer

Updated: Sep 5, 2023



Create showstopping displays in your spring garden by adding flowering bulbs to your autumn planting. Hardy, spring-flowering bulbs require advanced planning because they are planted in the fall, spend winter in the ground and flower in the spring. Some common hardy bulbs are tulip, iris, daffodil, crocus and lily.


WHEN TO PLANT BULBS

Spring-flowering bulbs need several weeks of cold temperatures to break their dormancy and flower to their full potential. In Minnesota (which ranges from USDA hardiness Zone 3 to Zone 5) spring-flowering bulbs can be planted as soon as the evening temperatures average 40° to 50°F and it is at least 6 to 8 weeks before the ground freezes (typically is September to mid-October). It is best to plant bulbs as soon as possible after purchase. However, bulbs can be stored until planting by following the care tips below.


BUYING AND STORING BULBS

  • Bulbs should feel firm to the touch, not soft or spongy.

  • Choose bulbs that don’t have any signs of mold, damage or bacterial infection.

  • At the time of purchase, bulbs should show little or no root growth or sprouting. Lilies are an exception, as they often have fleshy roots attached.

  • Don’t store in the refrigerator with fruit or vegetables that produce large amounts of ethylene because they can kill the plant inside the bulb. The most common culprits are apples, pears, avocadoes, cantaloupes, nectarines, peaches, peppers and tomatoes.

  • Bulbs need to breathe, so store them in aerated paper or mesh bags, never in plastic or airtight containers.

  • Plant bulbs in the same season they are purchased—they won’t last until next year.


PLAN BEFORE YOU PLANT

Many bulbs will come up year after year and spread informally throughout your garden. Careful planning will result in years of enjoyment from one planting.

  • Hardy bulbs need good drainage and sunlight. They like loamy or slightly sandy soil because it provides the drainage needed to keep from rotting. Soil pH of 6 to 7 brings out better flower color.

  • For the greatest visual impact, plant same-color bulbs in clusters or bouquets.

  • To extend the upcoming growing season, plant a combination of early-, mid- and late-season bloomers.

  • When planting varieties that will bloom at the same time layer plant heights front to back using a short-to-tall layout.

  • To keep the bed looking full when bulbs are dormant, combine with companion plants such as sedum, coral bells, hosta or bleeding heart.



STEPS FOR SUCCESSFUL PLANTING

  1. Plant bulbs in mass by digging up an entire area down to the proper depth (see Step 2), placing the bulbs and covering or plant bulbs in individual holes.

  2. Determine the planting depth for each bulb type that you’re planting. Different types of bulbs need to be planted at different depths. A general rule is to plant the bulb at a depth that’s three times the length of the bulb. If planted too deep, flowers will bloom late or not at all. If planted too shallow, new growth may become exposed too soon and be damaged by cold temperatures. See the planting depth chart provided by The University of Iowa Extension and Outreach for several bulb species.

  3. Prepare the soil by loosening it and mixing in organic material if needed to improve drainage or possibly added nutrients. Apply a slow-release complete fertilizer into the rooting area at fall planting. Follow the fertilizer label instructions. Clemson Cooperative Extension offers another fertilizing method which is to mix bone meal in the rooting area at planting time with an application of quick-release fertilizer at a rate of 1 to 2 pounds of 10-10-10 (a fertilizer that contains equal proportions of nitrogen, phosphorous and potassium) per 100 square feet in the fall. Repeat the application of 10-10-10 as soon shoots emerge in the spring.

  4. Place the bulbs with the pointy-end up and the roots down. If you’re not sure of the top or bottom of the bulb, plant it on its side and it will find its way to the surface.

  5. Cover the bulb with soil and a light layer of mulch.

  6. Thoroughly water newly planted bulbs.

  7. If needed, protect bulbs from critters by staking down wire mesh or chicken wire over the beds or planting them in bulb baskets or wire cages.


AFTER-BLOOM CARE

After blooming, cut the flower stem back. Leave the foliage intact until it turns yellow and wilts to the ground. The leaves are gathering and storing energy for next year and if the foliage is cut back too soon, the bulbs may not perform well or at all the following year. After the first frost, cut the foliage at the base of the plant, using your shears with 45-degree snips. In Minnesota, hardy bulbs can stay in the ground during the winter. Many will multiply and return year after year. Place a marker in the soil so that you remember where they are after you’ve cut the foliage back.


Additional Resources


Elizabeth Lorentz gardens at Mears Park in downtown Saint Paul. She loves cooking

and growing native perennial plants and herbs. She is a Master Gardener with the

Ramsey County chapter of the U of M Extension Master Garden Volunteer Program.


Photo credit: Ruth Johnson, Pixabay


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