Snapdragons (Antirrhinum majus) are vibrant additions to the garden, prized for their unique, colorful flower spikes. Although many gardeners treat them as seasonal annuals, these plants are technically short-lived, tender perennials. The decision of whether to cut them back before winter depends almost entirely on your local climate zone and whether you hope the plant will regrow the following spring. Understanding the plant’s biology helps determine the best approach for its survival and vigor.
The Decision: Annual Care vs. Overwintering
Snapdragons are often grown for a single season, but they are classified as tender perennials, meaning they can survive multiple years under favorable conditions. In regions experiencing prolonged hard frosts and deep ground freezing, snapdragons typically cannot survive the winter. The best practice there is to remove the spent plants completely once the foliage dies back. This annual approach ensures the garden bed is clean of potential disease vectors over winter.
When the ground does not freeze solid, often in warmer zones, the plant can survive the cold season and regrow in spring. In this scenario, cutting back is a strategic move to prepare the plant for dormancy. Leaving old, dead stems and foliage attached wastes the plant’s stored energy and exposes it to moisture and potential fungal issues throughout the wet winter months. Cutting back signals the transition to dormancy and directs energy reserves toward the root crown, where new growth will emerge.
This approach is only beneficial if the root system is expected to survive. Stems that are cut back but then killed by a deep freeze will not regenerate. The primary goal is to protect the perennial root crown from temperature fluctuations that cause freeze-thaw damage. Cutting back facilitates a cleaner, healthier transition into winter dormancy.
Essential Steps for Winter Preparation
Once the first light frosts cause the foliage to turn brown and wilt, prepare the snapdragons for their winter rest. The physical act of cutting back should be precise to maximize the plant’s chances of survival and regrowth. Use clean, sharp shears to cut the entire plant down, leaving short stems approximately four to six inches tall above the soil line.
This remaining stubble acts as a marker and provides a buffer for the central growth crown. Proper sanitation is also important, as dead or decaying plant material left on the ground can harbor fungal spores or insect eggs. All clipped stems, fallen leaves, and debris must be removed from the garden bed. This reduces the incidence of disease development during the long, damp winter period.
After pruning and cleaning, the next step involves providing insulation for the root system, which is the most vulnerable part of the plant. Apply a thick layer of organic mulch directly over the base of the cut-back plants. Materials such as straw, shredded leaves, or wood chips work well because they trap air and stabilize the soil temperature.
The mulch should be spread four to six inches deep, extending several inches beyond the plant’s immediate base to insulate the soil effectively. This protective layer slows the rate of freezing and thawing, which prevents the root crown from being repeatedly heaved out of the soil. This heave, caused by expansion and contraction, is often more damaging to the root structure than the cold temperatures alone.
Maintaining Growth and Health in Spring
As the risk of hard frost passes and the soil begins to warm in early spring, gradually remove the protective layer of winter mulch. Do not remove the insulation all at once; instead, pull back a portion to allow the soil to breathe and encourage the snapdragon to break dormancy. Initially, the overwintered plant may appear brown, but successful survival is indicated by small, green shoots emerging from the base of the trimmed stems.
Once these new shoots have developed a few sets of true leaves, encourage a stronger, bushier growth habit by pinching back the tips. Removing the terminal bud forces the plant to divert growth hormones to the lateral buds below. This simple pruning technique results in a more compact plant with multiple flowering stalks, leading to a more impressive display of blooms later in the season.