Celery (Apium graveolens) is a biennial plant typically cultivated as an annual. Growers frequently start celery indoors from seed due to its long growing season, allowing a head start before transplanting once the weather warms. Because the seeds are small and germination is slow, understanding the initial appearance of the seedling is important for monitoring success during this delicate stage.
Visual Identification of Celery Seedlings
The first structures that break the soil surface are the cotyledons, or seed leaves, not true leaves. These structures provide the newly emerged plant with initial energy until it can begin photosynthesis efficiently. In celery, the cotyledons appear as a pair of thin, elongated structures, often described as needle-like or spear-shaped.
Upon emergence, the color of these initial leaves is typically a pale, yellowish-green, quickly transitioning to a brighter green once exposed to adequate light. They are small, usually measuring only a few millimeters in length, reflecting the tiny nature of the celery seed. The seedling is highly susceptible to environmental changes at this stage.
The cotyledons are attached to a fine, almost thread-like hypocotyl, which is the young stem portion below the seed leaves. This stem is often translucent and fragile, barely strong enough to hold the seed leaves upright. The pair of cotyledons usually emerges in an upright or slightly V-shaped configuration, rising just above the soil line, marking the plant’s first contact with the external environment.
The hypocotyl may also exhibit a slight reddish or pinkish hue near the soil surface, especially under bright light conditions. This initial appearance is significantly different from the mature plant’s foliage, lacking the familiar ribbed stalks and segmented structure. Identifying this distinct shape confirms successful germination and differentiates the fragile seedling from any potential weeds that might also be sprouting nearby.
Transition to True Leaves
The cotyledons serve a temporary function, and the seedling soon enters the stage of producing its first true leaves. This transition signals that the young plant is ready to rely on its own photosynthetic capabilities rather than stored seed energy. The first set of true leaves develops between the cotyledons, emerging from the plant’s apical meristem.
Unlike the smooth, elongated cotyledons, the true leaves of celery possess the characteristic compound, segmented structure of the mature plant. They begin as tiny, lobed structures, showing the familiar divisions and slightly serrated edges. These leaves are a deeper, richer green color than the initial seed leaves, indicating higher chlorophyll content.
The appearance of the true leaves is a significant milestone, indicating the start of the vegetative growth phase. As these true leaves expand, the cotyledons will typically begin to yellow and eventually wither away. The development of this new foliage confirms that the plant is establishing the architecture needed to support future growth and the formation of edible stalks.
Understanding the Germination Timeline
Celery seeds are known for their slow germination process. Under optimal conditions, the initial cotyledons typically take between 10 to 21 days to emerge after planting. This extended period distinguishes celery from many common garden vegetables that sprout within a few days.
Successful germination is dependent on specific environmental factors, primarily temperature and light exposure. Celery seeds require warm soil temperatures, ideally maintained consistently between 70°F and 75°F (21°C–24°C). Celery seeds are photoblastic, meaning they require light to break dormancy and begin the sprouting process.
Consistent moisture is also necessary, as the seeds cannot dry out during the germination period. Using a fine mist or bottom watering helps maintain hydration without disturbing the tiny seeds. Providing these specific warm, well-lit, and moist conditions improves the likelihood and speed of the initial sprout’s appearance.