Lettuce is a popular, cool-season crop that thrives when planted correctly. Planting depth is important, as both tiny seeds and delicate transplants have specific requirements for success. Planting lettuce at the wrong depth can lead to poor germination or stem rot, preventing the plant from establishing itself. Understanding the instructions for both direct-sowing and transplanting is the first step toward a bountiful harvest.
Planting Lettuce Seeds
Lettuce seeds must be planted incredibly shallowly, typically between 1/8 to 1/4 inch deep. This near-surface planting is necessary because lettuce is a photoblastic seed, meaning its germination process is positively influenced by light exposure. Burying the seed too deeply in the soil prevents this interaction with light, significantly reducing the chances of sprouting.
Gardeners often scatter the seeds on the surface of the prepared soil. They then lightly dust the seeds with a fine layer of soil, compost, or vermiculite. This covering secures the seeds and maintains moisture without blocking the necessary light. If sowing in rows, drawing a shallow furrow and lightly covering them is effective. Maintaining consistent moisture in this shallow layer is paramount for successful germination.
Planting Lettuce Transplants
When planting lettuce seedlings purchased from a nursery, the depth requirement centers on protecting a specific area called the crown. The crown is the point where the stem meets the first set of leaves, and it is the region from which new growth originates. Unlike some other vegetable plants, lettuce stems will not develop new roots if buried deeper.
The transplant should be placed into the garden bed so that the soil line is exactly the same height as it was in the nursery container, or even slightly shallower. It is important to ensure the crown remains completely above the soil surface at all times. Burying the delicate crown area can trap moisture against the plant’s stem, creating an environment that encourages fungal diseases and causes the plant to rot at the base.
When removing the seedling from its container, handle the root ball gently to minimize disturbance. After placing the root ball into the prepared hole, firm the soil lightly around the sides. Take care not to push any soil up around the base of the leaves. This ensures the plant has good soil contact for moisture uptake while protecting the sensitive crown from burial and decay.
Initial Care After Planting
Immediately following planting, the first action is a gentle but thorough watering. This initial watering hydrates the roots and settles the surrounding soil, eliminating air pockets that could cause transplant shock. Use a soft spray or a watering can with a diffuser to avoid disturbing shallowly planted seeds or washing soil onto the exposed crowns.
For direct-sown seeds, thinning is necessary to prevent overcrowding and maximize leaf production. Once the seedlings develop their first one to two sets of true leaves, they should be thinned out to their final recommended spacing, typically between 4 to 12 inches apart. Removing the weakest seedlings allows the remaining plants to receive adequate light and air circulation, preventing stunted growth and reducing the risk of disease.
Lettuce prefers a location that receives full sun or light partial shade, especially during warmer periods. While the seeds need light for germination, young plants require sufficient light exposure to fuel rapid growth. Keeping the soil consistently moist but not saturated ensures a continuous supply of tender, non-bitter leaves.