When it comes to hydroponics, you can’t just miss lettuce. It is one of the most widely grown hydroponic crops. Due to the reasonable growing requirements and high yield, it is seen in every greenhouse. The growth rate is rapid where it takes nearly three weeks to show its first edible leaf. So, even if you are a novice in hydroponics, you can easily grow lettuce hydroponically.
How To Grow Lettuce Hydroponically?
As stated above, growing lettuce isn’t complex. A step-by-step manual and a little patience is what it takes. However, I listed some easy steps below to make it more concise. It will help you on how to grow lettuce hydroponically.
Step 1: Selecting The Place
The process of growing hydroponic lettuce must be initiated by selecting the proper place. Without the proper selection of location, your lettuce will be subjected to undernourishment. Many cultivate them under a Greenhouse environment, while others choose the backyard.
The ideal place for growing lettuce is where it receives optimum sunlight. On the other hand, it requires a humid environment. Usually, it germinates at temperatures between 4-30°C.
So, if your backyard is damp but receives moderate sunlight, it will be suitable to grow lettuce hydroponically. However, the yield can be multiplied at greenhouses. This is because you can control the external factors to an extent.
Moreover, it is necessary to keep the system invulnerable to pests. Therefore, always choose a hygienic location.
Step 2: Gathering Your Resources
The foremost step is to collect resources to grow hydroponic lettuce. There are numerous hydroponic set up across the globe. But the most convenient and straightforward setup, I feel, is the Deep Water Culture setup. This setup is nothing but the plan floating above a nutrient solution.
To build your setup, here are the items needed below:
- The Reservoir
- Growing medium
- Lettuce seedlings
- A luminous source (lamp)
- Air pump
- Air tubes
- Suitable net cups
- Starter plug cubes
The first item on the list is the reservoir. Many select plastic reservoir, and I insist you do the same. Don’t go for the metal Reservoir was as it might catch rust sooner than you expect. Moreover, the metal and solution might mix with the metal to form toxic substances.
The volume of your reservoir depends on the scale of your cultivation. If you are cultivating for your needs, I recommend you a 5-gallon bucket. Don’t go for a transparent reservoir as it might encourage algae and fungi growth. Then, your entire nutrient solution will facilitate algae growth.
But, if you have already purchased a transparent reservoir, paint it dark to make it opaque.
Regardless of the cultivation procedure, all plants need three necessary nutrients to grow. There are numerable fertilizers and growing medium in the market. But, you must select only those suitable for lettuce.
Check the pH level of the nutrient solution. In general, the pH for lettuce cultivation lies in the range of 6-7. So adjust by using a pH regulator accordingly.
Also check the ppm level. You can read our detailed post on right ppm for lettuce.
There are many varieties of lettuce you can choose to grow in your hydroponic system. See the detailed list of lettuce that you can grow hydroponically in this article. Crisphead, butterhead, and Romaine are some varieties suitable for hydroponics. I recommend you to extract the seed by yourself from a healthy plant, if possible.
The most important factor that decides the growth of your crops is the sunlight. Without proper sunlight, your lettuce can’t undergo photosynthesis. Face your hydroponic system in a way that it receives sunlight most of the day.
Make sure that your plants receive 9 hours of sunlight every day. I’ve seen many who installs a halogen bulb near the hydroponic system. Well, that’s an innovative alternative.
You may wonder: ‘What supplies oxygen to the roots. Well, in that case, we will need an air pump?’ In deep water culture systems, an air pump is the heart of the hydroponic system.
It is a submersible pump that supplies oxygen right at the roots of the plant. Besides the pump, take care of the tubing, starter clubs, and the net cups. It can easily be found online or in a nearby retailer.
Step 3: Planting The Seeds
The first query arising in your mind might be where to plant the seeds. Well, the starter plugs are manufactured for planting purposes. Each plug can hold numerable seeds, but I insist you plant only 2-3 seeds. See the complete lettuce seed germination process for hydroponics in this post ( click here to read the post) .
Planting more than three seeds in each plug will lead the plug to rapture during germination. It is also important to keep the growing medium moist and damp. On the other hand, you’ll need to take proper insurance on the sunlight.
The best way to satisfy both needs is to wrap plastic over the plug-filled net cups. Within a few days, you’ll notice water droplets on the plastic surface. To encourage further growth, you’ll have to pierce a few holes in the plastic.
After a week, I noticed the growth of root fibers. This is when you’re ready to transplant the lettuce plants to your Deep Water Culture system. In some cases, roots are seen on the 4th day.
Step 3: Transplanting To The Hydroponic System
Now, it’s time to plant your lettuce saplings in your hydroponic system. Initiate the transplantation by piercing holes in the net cups. The holes must be perfectly circular and mutually equidistant. To learn more about spacing for hydroponic lettuce read our detailed post.
Also, make sure that the holes are pierced not too close to the edges. If you lack tools, you can visit your local carpenter. Just tell him the requirements I mentioned above, and he’ll get it done.
After drilling, stuff your net cups with the growing medium, such as coconut choir or gravel. Don’t fill the cups to the brim. Only 1/3rd of the net cup must be filled with the growing medium.
I recommend you coconut choir because it will be damp for a long time. Now, put the starter plugs on top of the growing medium. Then, fill the remaining 2/3rd of the net cups with loose sand or gravel.
Doing such will make the plantation more compact and intact. Also, the intensity of sunlight that reaches the roots will get minimized. Thus, the moisture level in the growing medium will remain unhindered.
Now it’s time to set the circulation of the hydroponic system. Connect the tubes to the air pump leading to the air stone. The air stone acts as an adapter that helps in conveying oxygen to the roots.
After securing the connection, fill the reservoir by taking proper volume measurements. Remember not to fill up to the brim, as it might lead to nutrient overflow. The proper volume will be where you’ll submerge the bottom of the net cups about ½”.
Depending on the volume of water poured, assemble your nutrients. I recommended a 5-gallon reservoir. So, add five tablespoons of each assembled fertilizer.
Step 4: Pre-harvesting Period
The pre-harvesting period consists of the waiting period and maintenance. If you plant your lettuce in a region deprived of Sunlight, it will grow normal to the direction of sun rays. On noticing such behavior, move your system to a more bright location.
In case there is no such location, you can purchase a UV light. There are many quality UV lights available online. I’ve installed one for growing hydroponic lettuce and seen some remarkable growth.
The next threat to your hydroponic system is algae growth. Unwanted growth like algae and fungi increases the competitiveness for nutrients. If you see any such unwanted growth, eradicate it immediately.
Step 5: Harvesting Period
Now, the day has finally arrived to receive the output. After 45 to 50 days, your hydroponic lettuce is ready to harvest. There are several processes of harvesting.
You can harvest all the plants at once, but I recommend you to take only the edible leaf. Keeping the roots in the system will continue its growth. But, if you have no further horticulture plans, extract the entire plant.
Things You Need
1. Suitable Hydroponic Systems
The foundation for hydroponics is the cultivation system. For lettuce, there are six suitable hydroponic systems. To make the description more concise, below are the detailed review for each.
- Wick system:
One of the simplest systems to grow lettuce hydroponically is the wick system. It is so simple that it doesn’t need any pumps or electricity to operate. All you have to do is to place the plants in perlite or vermiculite and wrap nylon wicks around them.
See our post on how to build a wick system.
Lettuce requires high moisture growing medium. This necessity can be well-fulfilled by the wicking medium. Despite the sunlight, it never fails to enrich the plants.
- Deep Water Culture:
The Deep Water Culture system is opposite to the wick system by all means. The plants are directly submerged in the nutrient solution. Moreover, the stages in the deep water culture are more diverse than other systems.
The DWC(deep water culture) is the most suitable method to grow hydroponic lettuce. Also, it can accommodate large climbers and creepers like gourds and melons. Processing can be done on large and small scales.
- Flood And Drain:
This process is commonly known as the ebb and flow system. For home gardeners, this is the most accepted hydroponic system. The growing bed is spacious which is stuffed with a medium like Rockwool and coir. Plants must be carefully planned to make them stand firm on the loose growing medium.
After planting firm, you’ll have to add the nutrient medium to the growing bed. To restrict overflow, the solution mustn’t exceed the topmost layer of the medium.
- Drip System:
The drip system is probably the most accepted and practiced hydroponic system. It is suitable to grow hydroponic lettuce and other vegetables. Unlike the above procedures, the nutrient solution is directly pumped to the plant base.
You can read our detailed post on how to build a hydroponic drip system.
The reservoir is a separate body, where you’ll control the nutrient flow. However, the setup is complex and diverse, which is usually seen in greenhouses.
- N.F.T (Nutrient Film Technique)
The Nutrient Film Technique is a more targeted hydroponic system. The nutrient supply in N.F.T makes it different from other hydroponic systems. Nutrient flow in N.F.T is continuous and has stable layer thickness.
Click here to read our post on how to build a NFT system.
To be more specific, the moving nutrient layer will sweep through the lettuce roots. This reduces the necessity of a timer in the submersible pump of the system. Thus, the nutrient film technique is more preferable to the drip system.
2. Growing Seeds
A potential of seed can never be metered. Different seeds adapt to germination innumerable ways. When it comes to hydroponics, adaptation is what makes lettuce seeds remarkable. Growing lettuce hydroponically requires a wise selection of seeds.
The lettuce seeds are of a different complexion. But, they share one thing in common: tapered ends. It has a streamlined figure, which allows you to inject deep into the plug ends.
The drier the seed, the more durable it will be to store. If you purchase seeds from the retailer, don’t look for swollen ones.
3. Light Conditions
Light conditions are one is the most crucial aspects of how to grow lettuce hydroponically. Leafy plants, especially lettuce, need substantial sunlight to undergo photosynthesis. Sunlight is what produces chlorophyll, making them green.
An improper direction of sunlight might delay your harvest period. Moreover, you won’t get the expected quality. Don’t set your hydroponic system in a cool and damp area.
If your lettuce is growing normal to the sun rays, it isn’t receiving proper sunlight. I strongly insist you change the place to a more bright location.
Lettuce is not a hot weather crop. As stated above, it grows plenty in places within the temperature range 4°C- 30°C. If the temperature in your location exceeds 30°C, your lettuce will show flowers.
Well, that isn’t a good indicator at all. Lettuce flowers have a bitter taste which reduces its edibility. Therefore, meter your temperature before setting your system.
Studies show that the relative humidity must be 50-70 percent for growing hydroponic lettuce. Low humidity lowers lettuce’s resistance towards pathogens. On the other hand, high humidity makes the lettuce tip burn.
To be more specific, tip burn is a Calcium deficiency in leafy vegetables. Calcium is an important component of plant translocation. In the absence of calcium, your lettuce might turn salty.
Therefore, I recommend you to choose a site within the above-mentioned humidity range. You can also use an atomizer to increase the humidity in the hydroponics.
6. Nutrients for lettuce
Almost all green vegetables, including lettuce, are sensitive to nitrogen. So, your nutrient solution must contain elements of nitrogen, followed by phosphorus and potassium. Tip burn is the most common deficiency seen in lettuce.
To eradicate this defect, your nutrient solution must also contain calcium. Besides dissolved nutrients, ensure proper oxygen reception. You can ensure this by keeping the plant in a spacious location.
7. pH or Electrical Conductivity of the Water
Electrical conductivity is the property to meter the ionic movement. Nutrients will be present in the water in dissolved form. For a better ionic movement, the perfect value for electrical conductivity will be 1.45mS/cm.
Click here to buy a good quality EC meter for hydroponics.
On the other hand, it is also important to maintain the pH levels. The nutrient solution being too basic might give rise to burned tip lettuces. Therefore, the best pH level for growing hydroponic lettuce will be around 5.5-6.
8. Growing Medium
In Deep Water Culture systems, the nutrient solution is the growing medium after germination. Before germination, I insisted you starter plugs. It can hold enough moisture to mane the rupture of the seed in 4 days.
However, there are other alternatives too. Materials such as Rockwool and vermiculite can serve you with the same effect.
How Long Does It Take To Grow?
Hydroponic lettuce systems have different stages starting from germination to harvesting. To erase your confusion, I decided to dissect the lifecycle into three phases. These are mainly posted pre-vegetative stage, vegetative stage, and post vegetative stage.
1. Pre-vegetative Stage
The pre-vegetative stage consists of the planting and germinating period. This is when you inject the lettuce seeds to the starter plugs. The pre-vegetative stage terminates before the transplantation process initiates.
2. Vegetative Stage
The vegetative stage initiates with the transplantation process. After the seed germinates, it is placed on the nutrient solution. The vegetative stage continues until the growth of the first mature leaf.
3. Post Vegetative Stage
The post-vegetative stage is the final stage of the entire hydroponic process. This stage only consists of selective harvesting. It can be done by extracting the entire plant or just the roots.
For lettuce, the deepwater system is the best. It facilitates a dynamic ionic movement for faster results.
I made the Recommendations based on my experience. I hope this guide on how to grow lettuce hydroponically will answer most of your queries.