Fall is the season to think spring-flowering bulbs—colorful tulips, cheerful daffodils, fragrant hyacinths. To help make your spring garden as trouble-free as possible, we’ve answered some of the most commonly asked questions, here. For a list of recommended spring-blooming bulbs, see “Spring-Blooming Bulbs” in our information archive.
When is the best time to plant bulbs for spring flowers? Most bulbs can go in anytime from October through Thanksgiving. Tulips should wait until mid-November (soil temperatures need to be below 50°F), and can be planted as late as Christmas.
How should the soil be prepared? Amend soil with organic planting mix or composted manure, and work in thoroughly. Further amend with coarse builder’s sand or PermaTill® in poorly draining areas. Prepare soil 8 to 10 inches deep (for tulips, 12 inches).
How deep should bulbs be planted? Planting depth will vary greatly based on variety, so be sure to get directions when you buy your bulbs. As a rule of thumb, plant small bulbs (dime to nickel-sized) 4 inches deep; daffodils, hyacinths, and the larger alliums go 6 inches deep; plant tulips 10 to 12 inches deep.
When will fall-planted bulbs bloom? Blooming time depends on the variety. For earliest bloom, plant Winter aconite, Snowdrops, specie crocus, Chionodoxa, Iris reticulata, early daffodils, and early tulips (though even the earliest tulips still bloom a week or two later than most early bulbs). Mid-spring blooming bulbs (usually April) include Muscari, anemones, Fritillaria, Triumph and Darwin-Hybrid tulips, and most daffodils. Late spring-blooming bulbs (usually end-April to May) include late daffodil varieties, Single Late, Parrot, and Lily-flowering tulips, Dutch Iris, Scilla (Wood Hyacinths), and Alliums.
Don’t forget to add fall color to your garden with interesting and exciting fall-flowering bulbs like Lycoris (Spider Lilies, Magic Lilies, or Naked Ladies), hardy Cyclamen (which will often bloom for up to two months), sunny yellow Sternbergia, Colchicum (which are rodent-proof), and fall-blooming Crocus.
Are there bulbs that will tolerate shade? Try cheery little Muscari (Grape hyacinths), dainty white Galanthus (Snowdrops), or your favorite daffodil varieties. Other bulbs include the nodding flowers of Fritillaria meleagris (Checker Lily), Ornithogalum umbellatum (Star-of-Bethlehem), and the May-flowering Wood Hyacinths and English Bluebells. Springflowering Lily-of-the-Valley pips are available in February. Areas under deciduous trees, like oaks and maples, will often get full sun in early spring, before trees fully leaf out, and may support early-blooming sun-loving varieties.
Do I need to fertilize bulbs? Absolutely! Most spring-flowering bulbs benefit from a fall feeding (around mid- or late-October) of Holland Bulb Booster or 10-10-10 lawn food. If you prefer organic fertilizers, top-dress with composted cow manure in mid-fall. Feed again in the spring, about the time the leaves are just barely visible. Remember to water the fertilizer in lightly to ensure it begins to work into the soil.
How can I improve an existing bulb bed? If your bulbs are not blooming well, make sure they are planted at the right depth for the variety, and that they are receiving the proper amount of sun. If bulbs have been in the ground more than two years, you may need to dig and divide—best done in late spring when the foliage has yellowed or in early fall. Replant in soil to which organic matter has been added. Begin fall and spring fertilizing. Make sure ripening bulb foliage is not being removed until it is mostly yellowed.
What should I do once bulbs have finished blooming? Remove old or spent flowers, but NEVER remove leaves until they have yellowed and begun to “flatten” on their own. Do not tie leaves in knots or bunch them together with rubber bands. The leaves need to grow undisturbed, so that energy is transferred back to the bulb. To hide unattractive foliage, tuck leaves gently behind taller plants. Consider interplanting bulbs with perennials and groundcovers–their emerging spring leaves will help hide fading bulb foliage.
When is the best time to transplant bulbs? In Holland, they dig bulbs to be moved at the end of spring, and store them in a cool place until fall (an air-conditioned house, for example). You may also dig in early fall, then replant immediately.
What can I do about rodent problems? Rodents such as squirrels, chipmunks, moles, or voles, can be a problem for some varieties of bulbs. Try planting Colchicum or daffodil bulbs, which are poisonous and shouldn’t be bothered. You can also interplant these bulbs with more susceptible varieties to offer some protection. Alliums and Fritillarias are usually safe because of their unpleasant taste or odor. Minimize tulip loss by planting them 10 to 12 inches deep.
If drastic measures are necessary, try mixing sharp sand or small stones, or a commercial product called Perma Till, with your soil, or try lining your flowerbed with wire mesh. To repel deer and rabbits from munching on flowers or leaves, try spraying with the unpleasant tasting Hot Pepper Wax, or use one of the commercial repellents, like Messina Environmental’s line of Animal Stopper products.
How can I make bulbs flower indoors? To “force” most bulbs, choose early-blooming varieties or varieties that specifically say “suitable for indoor forcing.” Plant bulbs in pots, close to the surface of the soil, covering just to the tip. Water well, and place pot and all in the refrigerator for 10 weeks for crocus, 14 weeks for daffodils, and 16 weeks for most tulips, checking once or twice for water. After the chilling period, move the pot into a warm, sunny window.
If you can’t refrigerate, then you can allow Mother Nature to do it for you. Buy bulbs early (in September), and place bulbs in a paper bag in the refrigerator.
In November, pot bulbs as described above, and place pots outside in a cold frame or protected
area, surrounded by a generous layer of loose mulch, such as dried leaves or pine tags.
You can also layer bulbs in larger pots for a lovely spring-garden-in-one. Choose a container at least 10 or more inches deep.
Add 2 or more inches of soil, and place tulip bulbs on top. Add enough soil to cover tulip bulbs, and place daffodil or hyacinth bulbs on top, adding enough soil to cover. Top with small bulbs like crocus or Muscari, and finish off with enough soil to cover the bulbs to the tips. For added interest, top the pot with pansies in your favorite color.
For easiest forcing, try Paperwhite Narcissus, which will bloom quickly and with no chilling period necessary. Discard Paperwhites after flowering. Amaryllis are also very reliable indoor bloomers. Be sure to get directions on how to keep these beautiful giants from year to year.