Flower bulbs get the gardening season off to an early start. From the first crocuses and daffodils to the last tulips and alliums, it’s a show that can last from March through May. As spring eventually turns to summer, gardeners often wonder what to do about the spent flowers and fading foliage from these spring-blooming bulbs. To answer that question, you need to know if the bulbs will be treated as annuals or perennials.
Spring Bulbs as Annuals
Many spring-blooming bulbs return to bloom year after year. But not all of them behave this way. Tulips and hyacinths, for example, always look their best the first spring after planting. In future years, you typically get fewer flowers that are also smaller in size. To ensure a good show of color every spring, it’s best to plant fresh bulbs each fall.
If you are treating your spring bulbs as annuals, you should dig them up after they finish blooming. Use a garden fork to gently lift the bulbs out of the ground and then put them in your compost pile. Removing the bulbs as well as the foliage will help minimize problems with fusarium, a common fungal disease that can affect flower bulbs.
Growing spring-blooming bulbs as annuals does have some advantages. It guarantees you will always have a wonderful display of flowers. You also get the fun of putting together new color and texture combination each year.
Spring Bulbs as Perennials
Early-blooming bulbs such as snowdrops, crocus, chionodoxa, scilla and daffodils will flower year after year and multiply over time. These bulbs are reliably perennial and incredibly carefree. There’s no need to deadhead, fertilize or divide them unless they become overcrowded or you want to add them to other parts of your yard.
Hyacinths will usually bloom for several years, though the size of the flowers tends to gradually decline. Muscari and alliums will also return to bloom again if the soil is well-drained and stays relatively dry during summer and winter.
Tulips may bloom for several years if the soil conditions are ideal. Like muscari and alliums, they require loose, well-drained soil that gets hot and dry in the summer and stays cold and relatively dry in the winter.
When tulips are planted in heavy soil that holds too much moisture, the bulbs have a tendency to split. If you have ever dug up a tulip bulb after it has bloomed, you may have seen this yourself. Once a tulip bulb has split into two or more sections, it no longer has enough energy to produce a full-size blossom. Some types of tulips are less prone to splitting and more likely to rebloom. These include most species tulips, Darwin hybrids, emperor tulips and some triumph tulips.
Removing Spent Flowers
Smaller bulbs, such as crocus, muscari, scilla and snowdrops, multiply by seed as well as by bulb offsets. To encourage naturalizing, it’s best to leave the flowers attached so the seeds can ripen.
If you are growing tulips and trying to get them to rebloom, snip off the flowers right after they fade. With daffodils, the flowers may be removed for aesthetic reasons, but there's no other downside to leaving them on. The seed heads of alliums can be almost as attractive as the flowers, so you may want to leave them in place. Removing them doesn’t seem to affect the performance of the bulbs one way or another. Some alliums, including Purple Sensation, will self-sow. If you don’t want seedlings, you should remove the flower heads.
Hiding or Removing Bulb Foliage
Bulbs use their foliage to produce the energy they need to form new flowers. So, if you want your bulbs to rebloom, it’s important to leave the foliage in place until it has withered and turned yellow. When the foliage can be pulled away from the bulb with a gentle tug, it’s ready to go.
The foliage of early-blooming bulbs such as chionodoxa and scilla fades away very quickly. Larger bulbs take longer; a few weeks or a few months, depending on the weather and the type of bulb. There are several ways to cope with ripening foliage.
In perennial gardens, you can let the foliage of other plants hide the leaves. Hostas, daylilies, nepeta and perennial geraniums are a few of the perennials that are good at covering the spent foliage of tulips, daffodils and alliums. Click here for some recommended bulb and perennial pairings based on field tests at Cornell University.
Another option is to plant your bulbs in a dedicated area where you won’t mind seeing the foliage. For tulips and hyacinths, this could be in a cutting garden or even part of your vegetable garden. Alliums and daffodils are ideal for wilder areas where their ripening foliage will be out of sight. It's also possible to dig up your spring bulbs immediately after they finish flowering and replant them – with their foliage still attached – in a holding bed. When fall comes, dig up the bulbs and move them back.