How to Grow Romaine Lettuce Flower Seeds

Plant the romaine lettuce seeds or seedlings at least 25 feet from other lettuce plants to prevent cross-pollination. Allow the romaine lettuce plants to grow until they develop several leaves.

Select a healthy, vigorous romaine lettuce plant from the growing crop. Look for qualities you want to encourage, such as quantity of leaves, as the seeds will duplicate the parent plant.

Label the selected romaine lettuce plant to prevent early harvesting of the plant. Using plastic gardening labels, tie the label with garden twine to the base of the romaine lettuce plant.

Stake the romaine lettuce flower, when it develops, to support the flower and prevent it from breaking. Push a garden stake into the ground next to the romaine lettuce plant, then use garden twine to loosely secure the flower stalk to the stake. As the flower stalk grows, loosen and retie the garden twine as needed. The romaine lettuce plant will begin to develop a central flower stalk about 70 days or more after planting. The flowers will then develop small seeds.

Watch for the flower seeds to begin to mature. It takes two to three weeks for the flower stalk to develop and the seeds to mature. The seeds are flat and light-colored when they first appear, changing to plump and darker-colored seeds as they mature.

Remove the seed head, which is the seeded flower stalk, before the seeds are fully mature and blow off of the flower stalk. Use pruning shears to cut the base of the flower stalk when the seeds start to plump and darken and the romaine lettuce plant has started to dry out.

Place the seed head in a brown paper bag and set aside for two or three days until the seed head is dry. Harvest the seeds by crumbling the dry plant matter with your hands and picking out the mature romaine lettuce seeds.