Planting flower bulbs in March is entirely possible, but success depends significantly on the bulb type and the gardener’s geographical location. Bulbs are categorized by their required planting time, which dictates whether they will bloom in the current spring or wait until summer. Understanding the difference between these categories is the first step in ensuring a successful March planting. The practicality of planting in early spring is governed by soil conditions and the plant’s biological need for a chilling period.
Understanding Spring-Planted Versus Fall-Planted Bulbs
Bulbs are broadly divided into two groups based on when they require planting for optimal bloom time. Fall-planted bulbs, such as tulips, daffodils, and hyacinths, are designed to bloom early in the spring. These bulbs require a sustained period of cold temperatures, typically four to sixteen weeks below 45°F, to satisfy their vernalization requirement. This chilling period initiates the physiological changes that lead to flower formation.
Conversely, spring-planted bulbs produce flowers later in the season, typically during the summer or fall months. These varieties do not require a prolonged cold period to bloom and are sensitive to freezing temperatures. They are planted after the danger of the last hard frost has passed, making March a viable option for many gardeners. Examples of these heat-loving bulbs include Gladiolus and Dahlias.
Planting Summer-Flowering Bulbs in March
March is an ideal time to begin planting many popular summer-flowering bulbs, provided the soil is workable and not frozen solid. These bulbs, also known as tender bulbs, thrive when planted in soil that has warmed sufficiently, typically reaching a sustained temperature above 50°F. Planting too early into cold, wet soil can lead to rot.
Popular varieties like Dahlias and Begonias can be planted in March, especially in warmer gardening zones or if started indoors first. Dahlias should be planted with their eyes facing upward, approximately 4 to 6 inches deep, in well-draining soil. The tuberous Begonia is often shallowly planted, just below the surface, ensuring the concave side faces up to collect rainwater.
Gladiolus corms are an excellent choice for March planting, often benefiting from staggered planting every two weeks until June. This technique, known as succession planting, ensures a continuous display of tall flower spikes throughout the summer. Canna Lilies, with their tropical look, are also suitable for March planting. They should be placed deeper than Dahlias, about 6 to 8 inches down, to ensure stability for their large stalks.
For these tender bulbs, the primary risk is an unexpected late frost, which can damage emerging shoots. If the local climate still experiences hard freezes in March, gardeners can start these bulbs indoors in pots four to six weeks before the anticipated last frost date. This practice gives the plants a head start, allowing them to develop robust root systems and foliage before being transplanted into the garden beds once the soil has adequately warmed.
Managing Late-Planted Spring-Flowering Bulbs
The common gardening mistake is attempting to plant traditionally fall-planted bulbs, such as daffodils or tulips, directly into the ground in March. Since these bulbs were not exposed to the necessary winter cold, planting them now will not trigger the hormonal changes required for spring bloom. The resulting growth will be only foliage, or the bulb may fail to flower that season.
For those who missed the autumn planting window, one practical solution is to seek out pre-chilled bulbs from a reputable nursery or garden center. These bulbs have already undergone the required cold treatment, typically stored in commercial refrigerators for the necessary duration. When planted in March, they are ready to sprout and will often bloom, albeit sometimes later and with shorter stems than their fall-planted counterparts.
Another option involves forcing the unchilled bulbs indoors rather than planting them outside. By placing the bulbs in a pot with soil and maintaining them in a cold environment, such as a refrigerator or unheated garage, the gardener can simulate a winter season. After the cold period is complete, bringing the pots into a warm, bright room will prompt the bulbs to flower inside. While planting unchilled bulbs directly into the ground in March is generally unsuccessful for spring bloom, the bulbs will often survive, focusing on establishing their root system to bloom normally the following spring after experiencing a full winter cycle.