Magnolias can bloom twice, depending on the specific variety and environmental conditions. While most magnolias produce a single, spectacular flowering event in the spring, certain hybrid cultivars are genetically programmed to rebloom later in the season. Unpredictable weather or environmental stress can also occasionally trigger a sporadic second flush of flowers on standard varieties. Flowering more than once in a growing season is known as “remontancy.”
The Standard Magnolia Bloom Cycle
The primary bloom cycle for most deciduous magnolias, such as the Saucer and Star varieties, occurs in late winter or early spring. These trees are often among the first to flower, with large blossoms opening on bare branches before the foliage emerges. This initial flowering is the most robust event of the year, typically lasting for several weeks as buds open in succession.
The timing of this main bloom depends on the species, ranging from late February for Star Magnolias (Magnolia stellata) to April for many Saucer Magnolias (Magnolia × soulangeana). Evergreen types, like the Southern Magnolia (Magnolia grandiflora), generally bloom later, with their flowering period extending throughout late spring and into the summer. After the first bloom, the plant focuses its energy on developing leaves and setting the flower buds for the following year’s spring display.
Genetic Recurrence: Identifying Reblooming Varieties
A select group of magnolias possesses the genetic trait of remontancy, meaning they reliably produce a second set of flowers later in the year. This trait is highly sought after in horticulture and is a result of specific breeding efforts. These reblooming varieties set secondary flower buds during the summer that are distinct from the primary buds destined for the next spring.
Notable examples include cultivars from the “Little Girl” series, such as ‘Jane,’ ‘Ann,’ and ‘Susan,’ which are hybrids of Magnolia liliiflora and Magnolia stellata. These varieties, along with others like Magnolia ‘March Till Frost,’ are known for their ability to offer sporadic summer or autumn blooms following their main spring flush. This secondary bloom is generally less dense than the first, but it provides welcome color during the mid-season when most magnolias are only displaying foliage.
Environmental Factors Triggering a Second Flush
Standard magnolia varieties that are not genetically remontant can sometimes produce a sparse, unexpected second bloom in late summer or fall. This is typically a response to environmental signals that temporarily disrupt the plant’s normal dormancy cycle. A common trigger is a period of intense stress, such as severe summer drought or extreme heat, followed by a sudden return to cooler temperatures and sufficient moisture.
This stress can confuse the tree, causing it to prematurely open a few of the newly formed flower buds intended for the next spring. The resulting flowers are usually scattered across the tree, less impressive than the spring display, and are considered an anomaly. If these buds open early, they will not be available to bloom during the following spring’s main event, potentially reducing the total flower count for the next year.
Horticultural Practices to Support Rebloom
Gardeners with remontant varieties can encourage a healthy second bloom by ensuring the tree’s needs are met throughout the growing season. Adequate watering is important during the summer months when the tree is setting both primary and secondary flower buds. Consistent moisture prevents the drought stress that can either trigger a sparse, premature flush or prevent secondary bud formation.
Pruning should be performed immediately after the main spring bloom has finished, as magnolias set the following year’s buds on old wood during the summer. Pruning later in the summer or fall will remove these developing buds, eliminating the potential for both a rebloom and the next spring’s display. Fertilization should be managed carefully, avoiding excessive nitrogen, which promotes leaf growth at the expense of flower production.