Extension Educator, Horticulture
The daffodil blooms have blown and the tulip flowers have flown past another spring season. If we want to see a spring dance of flowers next year, we need to pay attention to how we treat spring flowering bulbs now.
After the flowers have faded, remove the old flower heads otherwise plants will expend energy producing unwanted seeds. Another key to maintaining healthy bulbs is to let the foliage turn yellow and die back naturally before cutting back. Bulbs need the leaves to replenish their food storage. Although it is best to let leaves die naturally, if it's driving you crazy to leave them you can braid, rubber band or otherwise tie the leaves together.
Also retain the foliage on the bulbs if you dig them to make room for other plants or to do bed redesign. To temporarily move bulbs use the "healing in" technique. Place the bulbs into a six-inch deep trench, cover with soil and allow the foliage to die back. The bulbs can remain in the temporary area until they are replanted in October. Just be sure to label them and delineate the area of bulbs with golf tees or other in-ground markers.
For healthy bulbs they can be fertilized shortly after they have bloomed by applying 5-10-5, 5-10-10 or similar fertilizer. Work it shallowly into soil and water.
If spring bulbs have not performed the way you had hoped, here are some possible reasons.
With new bulbs planted last fall:
If no foliage appeared this spring then either voles or squirrels got the bulbs or the bulbs rotted from excessively wet soils. Dig the area to determine the problem.
If foliage appeared but no flowers:
Bulbs were small sized when planted. With bulbs, bigger is better. Small bulbs will usually get big enough to flower in a year or so.
Bulbs planting area is too shady. Most bulbs need at least 6 to 8 hours of sun while the leaves are intact.
Bulbs are stressed from too much competition. Evergreen trees and fast growing plants may cause too much crowding and shading. Hostas and ornamental grasses are polite bulb companions.
Bulbs are planted in an area with poor drainage. They prefer spending their summer dormant season in dry soil. Also if bulbs share a planting area with summer-flowering annuals, the regular watering of the annuals may be too much water for the dormant bulbs. Bulbs may rot or perform poorly the next season.
Bulbs can get viruses which causes a loss of vigor and eventually death. Virus will often appear as yellow streaking or mottling on the leaves. Viruses can be passed to other bulbs so it's best to dig and destroy virused bulbs.Some spring-flowering bulbs especially tulips are treated as annuals since they rarely return with the size and quality of flowers of the first season. If long term tulips are your goal, look for those that are labeled "for perennializing" such as: Fosteriana; Greigii; and Kaufmanniana. With good growing conditions, these put on a good show each spring.
Bulbs may be too crowded after growing many years in the same location. Bulbs can be dug and divided once the leaves yellow this spring. Replant soon after digging.