An extremely fast-growing hydroponic crop, lettuce matures in about a month’s time. The small seeds are easily germinated in a soilless growing medium before being transferred into a hydroponics system fitted only with nutrient-rich solution.
The plant is a great source of minerals, fiber, and bioactive compounds—such as folate, B-carotene, and lutein—that promote a nutritious diet. Studies show that certain types of lettuces (particularly those with darker or red pigments as well as leafy types) have anti-inflammatory, cholesterol-lowering, and even anti-diabetic properties thanks to their bioactive compounds.
How to Plant Hydroponic Lettuce
Get started by germinating your lettuce seeds in a growing medium such as rockwool, lightweight clay aggregate, coconut fiber, or perlite.
Growing From Seed
Don’t expect all of your seeds to germinate property—it will likely be closer to 75%, depending on the type of lettuce. Fill your trays with a growing medium and slowly add water to make them moist but not soggy. Sprinkle up to three seeds in each plug and cover with about a quarter-inch of medium, compacting them slightly.
Continue to mist the seeds regularly to keep the growing medium moist as they develop. Once the plant has produced a few mature leaves and roots that stick out of the bottom of the medium (usually around two to three weeks or when they’re about 2 inches tall), it’s time to transplant them into your permanent hydroponics system.
Transplanting
When transplanting your seedlings from the plug trays to the hydroponic system, it’s important to avoid pulling too hard at the new stalks since it can easily kill the plant. Very gently, loosen the roots with your fingers and carefully place each seedling into its own pot, tucking the roots through the slats so they dangle into the nutrient solution below.
Get started by germinating your lettuce seeds in a growing medium such as rockwool, lightweight clay aggregate, coconut fiber, or perlite.
Growing From Seed
Don’t expect all of your seeds to germinate property—it will likely be closer to 75%, depending on the type of lettuce.2 Fill your trays with a growing medium and slowly add water to make them moist but not soggy. Sprinkle up to three seeds in each plug and cover with about a quarter-inch of medium, compacting them slightly.
Continue to mist the seeds regularly to keep the growing medium moist as they develop. Once the plant has produced a few mature leaves and roots that stick out of the bottom of the medium (usually around two to three weeks or when they’re about 2 inches tall), it’s time to transplant them into your permanent hydroponics system.
Transplanting
When transplanting your seedlings from the plug trays to the hydroponic system, it’s important to avoid pulling too hard at the new stalks since it can easily kill the plant. Very gently, loosen the roots with your fingers and carefully place each seedling into its own pot, tucking the roots through the slats so they dangle into the nutrient solution below.
Hydroponic Lettuce Care
It’s possible to grow practically every type of lettuce hydroponically, though gardeners tend to lean towards loose head varieties since it’s easier to harvest their leaves individually—thereby prolonging the entire plant’s harvest life. Some of the more popular types include the commonly grown butterhead lettuce, robust and crispy romaine lettuce, and varieties of mild loose-leaf lettuce.
Consider the fact that certain types vary in their growing times, as well.
How to Harvest Hydroponic Lettuce
With the exception of crisphead types (like iceberg lettuce), most varieties are best harvested by taking the bigger, outer individual leaves without removing the entire head. That way, the smaller, inner leaves have room to continue growing. That being said, you can also harvest the entire head at one time, though it will take longer—anywhere from five to six weeks—to develop.
To harvest the whole head of lettuce at once, either remove the entire plant by cutting from the roots or cut off all of the leaves at one time from the base of the plant.
If you plan on continuing your hydroponic lettuce garden, make sure you have replacement seedlings ready to replant into the system.
How to Store Hydroponic Lettuce
Individual leaves of lettuce should be eaten right away, though harvesting the entire head at once means it will stay fresh for longer in the fridge. To extend its life even further, wrap the crown in a damp paper towel or place the bottom in a shallow bowl of water.