Gather key lime seeds as soon as the fruit ripens to a solid, light green color. Pick two or three healthy, unblemished fruits directly from the tree rather than gathering them from the ground. Avoid fruit with bird pecks or other signs of damage.
Maintain constant, light moisture in the top 1 inch of growing mix. Water with a spray bottle to prevent the growing mix from becoming saturated. Always let the top 1/4 inch dry out between waterings.
Place the pots inside a lightly shaded greenhouse or indoors near a south-facing window. Arrange the pots on a germination mat that is set to 80 degrees Fahrenheit. Cover the pots with a clear plastic propagation dome or a sheet of plastic wrap.
Lemons and limes are both citrus fruits, and their juice and zest are often used interchangeably in recipes. So why do lemons (and most fruits) have seeds while limes don’t?
Speaking to Scientific American, two biologists at Brookhaven National Laboratory explain that normal fruit starts to develop when a flower’s egg cell is fertilized by pollen. Parthenocarpic fruit, in contrast, develops without fertilization. Fruit can be parthenocarpic for a variety of reasons, such as problems with the eggs or sperm, problems with pollination, or chromosomal imbalances.
The majority of limes sold in the U.S. are Persian limes (Citrus latifolia). While often thought to be its own species, the Los Angeles Times says this fruit is “a natural hybrid of true lime and citron.” Also called Tahiti or Bearss limes, these limes are parthenocarpic, meaning they’re produced without fertilization and are thus seedless. On the other hand, true limes (Citrus aurantifolia, but known commonly as Mexican, Key, or West Indian limes) do have seeds. Because Persian limes are bigger, have a thicker skin, and are more resistant to diseases than true limes, Persian limes have a longer shelf life. But where do they come from if they don’t have seeds?
Likewise, you can put seeds in a plastic baggie along with some moist soil. Regardless of the method you choose, keep the seeds moist (not soggy) and place them in a warm, sunny location. Germination usually occurs within a couple of weeks. Once seedlings have reached about 6 inches (15 cm.) tall, they can be gently lifted and placed in individual pots. Be sure to provide winter protection, as lime trees are very cold sensitive.
There are a couple of ways to grow a lime tree from seed and knowing how to plant a lime seed is important for success. You can plant the seed directly in a pot of soil or place it in a plastic bag. Before planting lime seeds, however, be sure to wash them and you may even want to allow them to dry for a couple days, then plant them as soon as possible. Plant seeds about ¼ to ½ inch (0.5-1.25 cm.) deep in containers with well-draining soil.
Keep in mind that other contributing factors, like climate and soil, also affect the overall production and taste of lime tree fruit.
Since many lime seeds are obtained from purchased fruit, they’re most likely hybrids. Therefore, planting lime seeds from these fruits often will not produce identical limes. Polyembryonic seeds, or true seeds, will generally produce identical plants, however. These can normally be purchased from reputable nurseries specializing in citrus trees.
Growing Lime Trees from Seed
In addition to nursery-grown plants, grafting is probably your best bet when growing lime trees. However, most citrus seeds are relatively easy to grow, including those from limes. While it’s possible to grow a lime tree from seed, don’t expect to see any fruit right away. The downside to growing lime trees from seed is that it can take anywhere from four to ten years before they produce fruit, if at all.
If you don’t want to wait so long for lime fruit production, you may want to consider other means of growing lime trees, which will usually bear fruit within three years. However, growing lime trees from seed is an easy and fun alternative to experiment with, keeping in mind that as Forrest Gump would say, “like a box of chocolates, you never know what you’re gonna get.”