How to Grow Lettuce in Aquaponics

Leafy green vegetables and herbs are one of the easiest and most successful plants to grow in aquaponics systems. They have lower nutrient requirements and are not difficult to keep up with. One popular crop that belongs to this description is lettuce. It is one of the easiest and most grown vegetables in aquaponics.

Lettuce is always in high demand, as it is an ingredient in most salads and comes in several varieties. This article discusses how to grow lettuce in your aquaponics garden, its specific growing instructions, and the best way of growing these delicious leaves. 

Why Grow Lettuce in Your Aquaponics Garden?

Lettuce is one of the best crops to grow in aquaponics, and here are several reasons why:

• Lettuce grows quickly by nature, and it grows twice as fast in aquaponics.
• Lettuce is super-low maintenance. It is not as sensitive to water temperatures as other plants.
• Growing lettuce in aquaponics takes little effort and monitoring.

What Lettuce Varieties are Best for Aquaponics

Any variety of lettuce grows well in aquaponics, but the three types that are popular for aquaponics systems are:

• Loose-leaf: Loose-leaf lettuce is one of the most common and the simplest lettuce to grow in aquaponics gardens. This variety adjusts to changes in water temperature easily, grows fast, and has a wide range of subspecies. Loose-leaf lettuce has a mild and sweet taste and is an excellent source of vitamin A.
• Butterhead: This lettuce variety is soft and tasty that gets its name for its buttery flavor. Butterhead lettuce variety is another excellent option for aquaponics because it grows quickly, tastes sweet and mild, and has a significant market value.
• Romaine: The romaine variety is one of the most sturdy lettuce to grow in aquaponics systems. This variety of lettuce is typically taller, thicker, and much more resistant to water temperature changes. 

How Long Does it Take for Lettuce to Grow in Aquaponics?

Lettuce is not just one of the fastest-growing vegetables in aquaponics gardens, and it is also one of the fastest-growing vegetables in the world. In traditional gardens, most lettuces grow in approximately 30 days, and the hardier and head varieties of lettuces grow in 45 to 60 days. However, in aquaponics systems, lettuces may grow two to three times faster because of their access to nutrient-rich water 24 hours a day. Meaning aquaponics lettuces could grow in as fast as two weeks. 

Ideal Condition for Growing Lettuce in Aquaponics 

Lettuce might be easy to grow in aquaponics gardens, but it still needs the ideal conditions to grow and thrive. That means understanding its nutrients, temperature, and pH requirements is essential. Here are the factors you need to know to grow your lettuces in aquaponics successfully. 

• pH level: The ideal pH range for lettuce is between 5.8 and 6.2. However, lettuce is a robust crop and can survive with pH levels outside this range. 
• Water and Air: Lettuce thrives in the water temperature range of 70° to 74° (21-23°C), which is also the ideal temperature for many aquaponics fish.
• Plant Spacing:  Space your lettuce at least 7 inches apart. This space will encourage maximum growth, prevent overcrowding, and ensure each plant receives enough light. This spacing will also depend on the lettuce variety you’re planning to grow. 
• Recommended Fish:  The recommended fish that match lettuce in aquaponics systems are tilapia, trout, bass, sunfish, koi, carp, and goldfish.

Methods for Growing Lettuce in Aquaponics

There are multiple ways of growing lettuce in aquaponics, but the best approach is the floating raft and media bed methods.

1. Floating Raft or Deep Water Culture (DWC)

The raft method or DWC uses rafts made of polystyrene that float on the water. The lettuce seeds are placed in foam sponges and a net pot. The net pot is then placed in holes in the raft where the roots will hang and access the oxygenated, nutrient-rich water. This will give the roots access to the nutrients they need to grow quickly.

2. Media Bed

Another option to grow lettuce in aquaponics is through growing beds in a media bed method. This method involves planting lettuces in a grow bed. The bell siphons flood and drain the grow bed, and the roots will have access to the nutrient-rich water they need to grow quickly.

Instruction on Growing Lettuce in Aquaponics

How to Start lettuce Seeds for Aquaponics

1. Place at least 3 to 5 seeds in a starter medium (this could be Rockwool 3D squares, peat pellets).
2. Stick the 3D squares or pellets into a starting tray and water them.
3. Mist the tray once a day for as long as fourteen days.
4. After 10 to 15 days, the seeds will sprout and transfer them into your system when the seedlings are large enough or when two or three true leaves start to come out. 

Transplanting Lettuce in Aquaponics

Lettuce seedlings can be transplanted into the system after three weeks. If you are transplanting in a colder climate, make sure to expose the seedling to the colder temperature and direct sunlight for at least 3 to 5 days to ensure the seedlings can adapt to the colder climate. If you’re transplanting in warm weather, make sure to put a sun-shade over the seedlings for 2 to 3 days to avoid stress. Always maintain a high nitrate level in the system to ensure you have crisp and sweet lettuce. 

Maintenance

Growing lettuce in aquaponics systems is easy to maintain. Below are some things you need to check regularly to ensure a successful aquaponics garden.

1. Check the pH level every week. The ideal pH is 6.8, and if the level is more than 7, the pH should be adjusted to a lower level.
2. Make sure to use de-chlorinated water when you need to add water to the system.
3. Check for pests. If there are any pest infestations, make sure to remove the pest without using pesticides because this might harm the fish. You can physically remove any pests you see or use beneficial insects to eat the pests. You can also use the companion planting method to avoid pest infestation in your aquaponics garden. Chives or mints are great companion plants for lettuce. 

Harvesting

Lettuce grows so fast in aquaponics that it can be harvested in as short as two weeks or when you notice the heads and leaves are large enough for consumption. It is recommended to harvest early in the morning while the leaves are crisp and moist. After harvest, chill the leaves immediately to maintain their freshness.

Conclusion on Growing Lettuce in Aquaponics

Lettuce is an excellent starter plant for beginners in aquaponics and newly built aquaponics systems. So if you’re new to aquaponics, lettuce is the perfect crop for you to grow. However, even if lettuces are easy to grow, you still need to follow the guidelines above and monitor your garden to ensure your attempt at aquaponics gardening will be successful. Thank you for reading this article and feel free to leave a comment below.