If the plants are not receiving enough light, they may become spindly or fail to thrive. Depending on the lights you use and your particular setup, you may need to bump this up or down. How long does lettuce take to grow in hydroponics? This is called a lettuce raft. As lettuce is literally all leaves, out of all of the essential nutrients your hydroponic lettuce needs, potassium is required in the largest amounts by far. The amount of light varies depending on what type of plants you are growing. Most people dont taste any difference at all. Blue Light Spectrum, the wavelength of light here, is between 400 and 500 nm. When you think hydroponics, the first vegetable that comes to mind is probably. This is the most expensive element of the lighting system, so it must be kept off the ground to ensure that it never gets wet in case of a flood or leak. Hydroponic lettuce may taste different based on the nutrients you provide it, the temperature, and several other factors, but in general, hydroponic lettuce and lettuce grown in soil taste the same. Hydroponic lettuce offers a variety of types and flavors, suitable for nearly any palette. The best answers are voted up and rise to the top, Not the answer you're looking for? so now if that has you all confused its not that hard to go by . Lettuce needs 12-14 mol/m-2/day which equals if you have a light system putting out 280 ppfd the DLI will be about equal to the number of hours the lights are on 12 hr = 12.1 dli , 14 hrs = 14.11 dli . Grow greens, herbs, vegetables and fruit all year long By 80 Watt, I guess you mean an 80 Watt (incandescent) equivalent. You dont need to make any modifications to your Kratky. However, for lettuce, you probably want mostly the higher color temperatures which should help the leaves grow most. I give my lettuce 10-12 hours of light from a LED grow light. DLI is calculated by measuring the photosynthetic photon flux density, which is how much light within the wavelength that plants need. Start your seeds in jiffy pellets or starter plugs. Lettuce has low light requirements and they are fast-growing. . Each type has its benefits and drawbacks, so it is important to do your research and choose the one best suited for your needs. You can keep these light features in mind when choosing a grow light: All plants have different light spectrum requirements. Examples include rice, eggplant, roses, and corn. What Types of Plants Can Grow in a Hydroponic Garden? How many hours of light does hydroponic lettuce need? Forgetting to stratify seeds. This post contains affiliate links. For flowering/fruiting plants, I would actually recommend using more than one color temperature (like a 2500k one and a 5000-7000k one, if not more than two). The Kratky method uses no pumps or airstones. How much light does lettuce really need? If you decide to mix short- and long-day plants in one growing system, it is best to compromise their needs and pick a lighting schedule that is right in the middle: around 14 hours of light per day. The best way to provide this light is through fluorescent grow lights, which are ideal especially when you are first starting your lettuce garden. In her spare time, she enjoys reading gardening magazines and attending local horticulture events. Romaine lettuce. You can also severely cut down on the amount of light (and electrcity) you need to use, by putting highly reflective material around the lights, so it bounces back on the plants. . Unfold the paper towel to check on them. Make sure to put your container in a place that gets a good amount of sunlight. Average Life Span & Key Care Tips. Why is this sentence from The Great Gatsby grammatical? Leaf lettuce is probably best. Some growers use a piece of floating Styrofoam cut to fit inside their tote. It is also important to monitor the plants as they grow. As soon as you start growing lettuce, you should use fluorescent grow lights to illuminate it. Lettuces, in particular, are highly susceptible to dangers like e.coli. If you don't have a sunny window, you . Once they get their true leaves, I run the lights 10-12 hours per day. In reality, getting to the bottom of a plants optimal light requirements is very technical. DLI is calculated by measuring the photosynthetic photon flux density, which is how much light within the wavelength that plants need. Also, the soil itself may be present on the plant, which no one wants to eat. How much light does Lettuce need per day: Indirect vs. When grown outdoors, lettuce tastes best during the spring and fall. . This includes keeping the nutrient. You will need to gently wash away as much of the soil as you can. This isn't really an answer, but have you considered running small-scale experiments? To grow hydroponically, you need plants, a container, water, a way to anchor the plants, nutrients and a light source. In the summer heat, they undergo changes and start to bolt, creating a bitter flavor. They are not the most common you will find. Here is a picture of the roots in my modified Kratky system. They also get some window light. Red and green varieties are frequent hydroponic favorites and quite attractive on a plate or sandwich. Optimizing Plant Growth with Indoor Lighting Q&A. Lettuce is a low-light plant and it won't do well in full sun. Neither is needed but I think there is an advantage to adding airstones. You can spend money for the grow bulbs but I would not bother at this point. Thanks to products like Lettuce Grow's Farmstand, even those without a lot of outdoor space can easily and conveniently grow produce at home. Two pounds of fertilizer is enough to make 128 gallons of nutrient solution. Is a lighting system required for hydroponic gardening? So its not simple thing pop a couple bulbs out throw a lumen number at them and say ok plants will grow, yes maybe they will grow but not at the best or optimum for the plant. This page might be helpful under the heading: How much light should plants receive? When the plants are germinating from seed (until they get their first true leaf, most often the third one), I run the lights about 6 hours per day. The roots in the water are feeder roots. Once they show signs of sprouting transfer them into your peat pellet or started plug. Eunice takes great pride in her garden and often shares the fruits of her labor with friends and family. Use the tubing to connect the water pump to the container of nutrient solution. From personal experience I know these lights work well with lettuce and basil. The color of your lettuce may impact your light requirements. Lettuce growth depends on the interactions of blue and green light, but it is not clear how phosphor-converted broad spectra, with or without supplemental blue and red light, influence crop growth and quality. And fluorescent light works best as it is of a reasonable cost, especially if you are a beginner and are only trying out. That's a big number. Bolting just means that growth in the lettuce quickly shifts from leaf growth to flower and seed growth. Eunice has been gardening for over 15 years and has developed a unique style of landscaping that is both practical and aesthetically pleasing. In general, your NPK levels should be as follows: Nitrogen: keep the nitrogen level at approximately 5. Mix well. Check the nutrient solution regularly and add more as needed. Choosing the best lights for your hydro system can be daunting. Thanks. "High humidity also favors the physiological disorder tip burn. Youll also need a water pump, tubing, and timer. For most types, youll want to only cut the outer leaves each time you harvest, allowing the core and roots to remain and continue growing. Water your seeds a few times per week. . "cool white" (more "blue") lights tend to be more beneficial for vegetative growth, while "warm white" (more "red") helps flowering growth, I believe, so if you get a shop light, get the cool white bulbs for this. No its equivalent is about 400 watts (or so they say) it is an 80 watts CFL bulb - here is a a brand. Hydroponic systems today are very sophisticated; there are systems that will monitor the level of nutrients pH, and temperature of the water, and even the amount of light the plants are receiving. Leafy greens, and lettuce especially, are perfectly suited for hydroponic systems. Low humidity affects calcium uptake, which affects photosynthesis and fruit quality. How much water do these hydroponic office plants need? Manual timers use pins and have two plugs on either side so that you can attach two grow lights at once. When this happens, your lettuce plant will taste annoyingly bad. Because of their large, flexible leaves, these plants are an excellent choice for salads, sandwiches, and lettuce wraps. I have had success with an 80 watt compact fluorescent light (CFL) within 5 cm of the plants, you can grow at least 6 plants. The appropriate temperature during the day should be from 65 to 70 degrees Fahrenheit. PAR is more accurate but for practical purpose lumens is useful if you know the spectrum of the light. A fertilizer high in nitrogen and potassium will work best. I'm trying to figure out the costs involved with the electricity of the lights. Your tomatoes should get at least 12-18 hours of light daily. A great all-in-one option is the Masterblend Complete Combo Kit Fertilizer. With lettuce hydroponics, it's best to germinate your seeds in an egg carton or similar environment, filling the spaces with the growing medium you prefer. I decided to add airstones to mine. Hydroponically grown produce has the same nutritional benefits as its soil-grown counterparts and is typically fresher when it arrives to the consumer. Water is heavy, about 8 pounds per gallon. The most common types of bulbs are LED, fluorescent, metal halide (MH), and high-pressure sodium (HPS). A nutrient solution is made by combining a balance of hydroponic nutrients with purified water. They can be grown all year round in a controlled environment. Because of this, it is grown by the masses which makes it more susceptible to recall and contamination. There are a few ways lettuce can be contaminated when its grown in a hydroponic environment, but its still best to wash vegetables before consuming them. But I decided to hot rod it a bit by adding airstones. This is why we have put together information on hydroponic lettuce light requirements for you.Advertisement.box-3{text-align:center;padding-top:20px!important;padding-bottom:20px!important;padding-left:0!important;padding-right:0!important;background-color:#eee!important;outline:1px solid #dfdfdf;min-height:305px!important}if(typeof ez_ad_units!='undefined'){ez_ad_units.push([[300,250],'growertoday_com-box-3','ezslot_11',104,'0','0'])};__ez_fad_position('div-gpt-ad-growertoday_com-box-3-0'); One simple vegetable to grow with hydroponics is lettuce and its a perfect vegetable to start with especially for beginners. Growertoday.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com. The required pH for hydroponic lettuce ranges from 5.6 to 6.2. Learn more about Stack Overflow the company, and our products. 650 to 700nm is Red and used for flowering and fruit ripping, yes? You can grow just about anything in a hydroponic greenhouse, but it's important to choose plants that will do well in water. While it would initially appear you want more blue light, that is not how photosynthesis works when you get down to the nuts and bolts. What is the point of Thrower's Bandolier? Nearly any type of lettuce can grow well in a hydroponic environment, but some of the most popular varieties are romaine, red and green oak leaf, and butterleaf. Learn tips for creating your most beautiful (and bountiful) garden ever. However, a better strategyespecially for home growersis to periodically harvest lettuce leaves as they come in or as they are needed. Harvest your lettuce when it is ready to eat. Start growing hydroponic lettuce indoors with the Kratky method. In fact, harsher light increases the bitterness you'll experience in a leaf. I have been to many hydroponics stores and seen almost all the lettuce hydroponics videos on youtube. I would recommend using House And Garden Aqua Flakes because it is easy to calibrate without a meter. But eventually, over time the plant will go to seed or become bitter. A lot of commercial lettuce is grown this way. Plants mostly require light in wavelengths of around 430,450,650,675 nano meters (depending on the crop), with highly varied intensity requirements from crop to crop. The pots will fit perfectly. A laser temperature gun can help determine if the intensity is resulting in too much heat. Also a T5 is not by any means overkill. Arguably perfect for lettuce. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. For most leafy greens use a red:blue ratio of 5:2, this will be sufficient to promote good growth. Lettuce is one of the most common hydroponic crops because its easy to grow and rapidly reaches maturity. Growing conditions for hydroponics - Vanilla Planfolia and Saffron (Crocus Sativus), Lighting for indoor citrus to produce full fruit, How to handle a hobby that makes income in US, Bulk update symbol size units from mm to map units in rule-based symbology, Euler: A baby on his lap, a cat on his back thats how he wrote his immortal works (origin?). You can probably start harvesting leaf lettuce in 3 or 4 weeks. BTW, if you are in a cold climate where the inside air in the winter is very dry you will get better results if you enclose your growing area as much as you can and do everything you can to keep the humidity up. How To Keep Cut Flowers Fresh Without Water: Full Guide. The morning lettuce will taste sweet and the heat-burdened afternoon lettuce will taste bitter. Is there a proper earth ground point in this switch box? How long does lettuce take to grow hydroponically? But they also go to seed with long daylight hours. How Much Light Is Needed for Hydroponic Lettuce? Stratification (also known as cold stratification) doesn't apply to all seeds, but it's the number-one reason some seeds take their sweet time germinating (or refuse to germinate at all). Compared to many options, romaine lettuce is one of the easiest plants to grow hydroponically. Making statements based on opinion; back them up with references or personal experience. A head of lettuce will keep producing under these conditions for many weeks until it ultimately starts to bolt. Plants were thinned to one per pot and two weeks later the remaining plants just went crazy. The cheapest way to do it is wire your own panel using keyless lamp holders and bulk buying the CFL's. Your tote can be any size but it should be opaque. You can start your seeds in a damp paper towel by folding them over. Acidity of alcohols and basicity of amines, Full text of the 'Sri Mahalakshmi Dhyanam & Stotram'. If they are exposed to more than 12 hours of light per day, they will not flower. If we talk about the natural sunlight, it will be enough for the herb to spend 6 hours in the sun. For more advanced growers, the best option is to make a dry fertilizer mix yourself. To learn more, read our guide to hydroponic romaine lettuce. Plants grown under lights indoors need more hours of light than the same plants do outdoors. Think of it like filling a jug of water. On the other hand, they may become stressed or burnt if they receive too much light. Eight hours is the minimal quantity of daylight required for strong leaf growth, according to a trial study conducted in 2019 at Ohio State University. Harvest can be incredibly simple if youre not concerned about regrowing your lettuce from the same root system. Timers are the least expensive piece of the lighting system, but they are incredibly important. and these are converted to DLI Daily light integral (DLI) describes the number of photosynthetically active photons (individual particles of light in the 400-700 nm range) that are delivered to a specific area over a 24-hour period. Recently transplanted butterhead seedlings in our R&D vertical greenhouse. What is the best nutrient for hydroponic lettuce? He said the lower humidity helps to limit pathogen issues. If you use these links to buy something we may earn a commission. Check out TrueLeaf Market for 20+ varieties of lettuce seeds! If you're growing lettuce in a sunny window, make sure to rotate the plants regularly so all sides receive equal exposure to the light. Whats the best lettuce to grow hydroponically? But it has the advantage of being protected from the contaminants that so often lead to food recalls. Lettuce, for example, prefers a range high in blue light. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Grow these until the seedlings are 2 inches (5 cm) tall and have about 4 leaves. That way you can harvest and replace plants periodically. My hydroponic lettuce has really taken off. Most lettuces thrive in cooler weather and typically grow outdoors in the cooler months of the spring or autumn. That is it! The consent submitted will only be used for data processing originating from this website. Today 2017, many of your indoor vertical farms are playing with the r:b ratio to affect taste, color and texture. Bibb and Boston lettuce are both types of Butterhead lettuce. If you are growing your lettuce indoors, place it near a south-facing window. So it will keep growing and provide multiple harvests. Two plants need at least 60 watts. Since its up to 95% water, it can have a hydrating effect, and its vitamin A is good for the eyes. How many lumens do I need for lettuce to grow? 7 Expert Tips For Beginners, Growing Coconut Trees In Containers: 7 Tips And Tricks For Beginners, Cardboard Palm Care Indoors: Easy 9 Step Complete Care Guide. WhyFarmIt.com is a participant in the Amazon Services LLC Associates Program. It increases the effectiveness and efficiency of the bulb by reflecting the light down onto the plants at multiple angles, giving a more effective spread. How much is this exactly? Hydroponic lettuce can last two to four weeks if harvested with the roots intact. Anything else lettuce might grow but it will be elongated and not form proper lettuce heads. You just built yourself a Kratky for lettuce. Lettuce does well in cooler temperatures. You can determine the power of light using a PAR meter or the manufacturers recommendations. Others, like Iceberg and denser, sturdier lettuces, are ready to harvest in six to eight weeks. 1 Artificial lighting for a hydroponic garden should imitate direct and indirect sunlight requirements. I planted a mixed pack of leaf lettuce so I have 3 or 4 different kinds. Naturally, lettuces develop leaves incredibly quickly, but putting them in hydroponic systems is like super-charging them. I recommend using hydroponic nutrients to feed your lettuce plants. Outside, a vegetable garden requires around eight hours of direct sun per day. The texture is crisp, and the flavor is slightly sweet. You might have to adjust the size of your grow light. Mattson said the relative humidity for lettuce and leafy greens should be between 50-70 percent. Why does Mister Mxyzptlk need to have a weakness in the comics? Here is everything you need to know about hydroponic lettuce. It is a 2 part A+B hydroponic nutrient. Most lettuce varieties will regrow three to five times if harvested carefully. You will see about 80-100k at around 6 inches from a T5. The easiest way to maintain a lighting schedule is with an automatic electric timer. Keep the room temperature between 55 Fahrenheit at night and 75 Fahrenheit during the day, as lettuce needs to grow in a cooler environment, although this may be surpassed taking the right compensatory actions. We are reader supported. I'm guessing they grow toward blue light more than red. Lettuce is a minimally demanding plant when grown hydroponically. To supply the right balance of nutrients to your plants, you will need the right hydroponic fertilizer. Hydroponic strawberries need at least 8 - 12 hours of direct sunlight daily. Fluorescent lighting does not cost much, power consumption is low, and heat production is minimal. My electric bill is lower and they will be slower to bolt and go to seed. Here is some more info on the Kratky method: Windmill Palm Care: 9 Tips And Tricks For Beginners, Christmas Palm Indoors: 5 Easy Adonidia Merrillii Care Tips, Are Grow Tents Worth It For Vegetables? rev2023.3.3.43278. You will want to fill your Kratky with water and nutrients about an inch above the bottom of your net pots. place this over the iphone front camera lens and use korona to measure light and korona has options to show ppfd - dli - and if curious lux plus can upgrade app to also show kelvin scale. Mary has been a Master Gardener for 30+ years and a commercial and residential gardener for 50+ years. It all starts with quality seeds. It is cheap and easy to set up. Learn More About Our Innovative Hydroponic Greenhouses. A good nutrient mix for lettuce is, for every 5 gallons of water, 2 teaspoons of 18-15-36 NPK organic fertilizer and then 2 teaspoons of calcium nitrate and 1 teaspoon of magnesium sulphate of you want to make your own. [10] 2 Transplant your seedlings to the reservoir. How much light do hydroponics strawberries need? Ready to grow some hydroponic lettuce? This means you can store it various ways without worrying about it going bad. So, for example 6 ml of each per gallon would make a gallon of 600 ppm nutrient solution. Building a hydroponic system for lettuce is a fun and rewarding project. We grew red-leaf lettuce 'Rouxai' in an indoor deep-flow hydroponic system at 22 C air temperature and ambient CO2. You can find out more about our use, change your default settings, and withdraw your consent at any time with effect for the future by visiting Cookies Settings, which can also be found in the footer of the site. It is the perfect choice if you are just starting out with hydroponics. You need to maintain at least 60-75% relative air humidity-a higher nighttime humidity benefits nutrient movement during the day. Classic Romaine. This also allows you to use lights that give off less heat, saving on electricity and cooling costs. Not a lot of light? Amazon, the Amazon logo, AmazonSupply, and the AmazonSupply logo are trademarks of Amazon.com, Inc. or its affiliates. This pH range is acidic enough to reduce the activities of algae and at this pH range, plants can absorb nutrients adequately for their growth. Light is measured by DLI or daily light integral. But a grow light the gives actual numbers as stated in lux and ppfd as tested in sphere and watch out for lights that tell you " yes replaces lights of XXX watt much lower watt but dont give you a hard data sheet of the light wave length, and actual wall watt draw. Ready to grow some hydroponic lettuce? Indoor growers usually wont have temperature problems. The main types of hydroponic systems are the DWC, drip irrigation, ebb and flow, Kratky method, NFT, and the wick system. They are small and you want to make sure each planter has at least one healthy plant. Start them in starter plugs like Root Riots or in Jiffy pellets That way you wont have to wash off the dirt like you do with store bought transplants. If you go larger they will fall through. For most varieties, you can have fresh, healthy leaves ready to harvest within six to eight weeks. Since theyre delicious and versatile, theyre also perfect for your hydroponic farm. I'm guessing since Merlot lettuce is dark red, it would prefer a higher color temperature even more than regular lettuce, since lower color temperatures have more red, and the lettuce would reflect more red (rather than absorb it), because it is red. Here are the steps you can follow to build your hydroponic system: Several parts determine the efficiency of a grow light. An example of data being processed may be a unique identifier stored in a cookie. You can use starter plugs like Root Riots too. Yes! For new growers, the easiest and most effective option is to get apremade dry mix of nutrients specially designed for lettuce. We and our partners use cookies to Store and/or access information on a device. Milkweed seed podslet them self-sow or sow them in fall. Ways to Use (given that this question's two years old, perhaps you've moved on already) You might be able to assemble a cheap setup with a desklamp and a CFL, and try at least one case. Here are our suggestions for the best types of lettuce for hydroponic growers: Butterhead lettuce offers a velvety texture and a buttery taste. That said, its still essential to understand the proper conditions for optimal growth. I am growing a mix of buttercrunch and leaf lettuce in my tote. They send nutrients up to the plant. It flourishes under growth chamber conditions. You do not want light getting in the reservoir. I found some for only 6 USD in my local store here in Berlin. "High humidity favors powdery mildew and Botrytis," he said. Nitrogen levels will determine how tall your plants grow. Fletcher, I guess you meant 400 to 450nm wavelength for Lettuce? Watch giraffes eat our delicious hydroponic lettuce! Short-day plants: These require a long period of darkness to photosynthesize and produce flowers. Manage Settings if(typeof ez_ad_units!='undefined'){ez_ad_units.push([[300,250],'growertoday_com-banner-1','ezslot_9',140,'0','0'])};__ez_fad_position('div-gpt-ad-growertoday_com-banner-1-0');if(typeof ez_ad_units!='undefined'){ez_ad_units.push([[300,250],'growertoday_com-banner-1','ezslot_10',140,'0','1'])};__ez_fad_position('div-gpt-ad-growertoday_com-banner-1-0_1');.banner-1-multi-140{border:none!important;display:block!important;float:none!important;line-height:0;margin-bottom:7px!important;margin-left:auto!important;margin-right:auto!important;margin-top:7px!important;max-width:100%!important;min-height:250px;padding:0;text-align:center!important}Lets take a look at some other growing requirements: Below are the commonly grown types of hydroponic lettuces:if(typeof ez_ad_units!='undefined'){ez_ad_units.push([[300,250],'growertoday_com-box-4','ezslot_7',107,'0','0'])};__ez_fad_position('div-gpt-ad-growertoday_com-box-4-0');if(typeof ez_ad_units!='undefined'){ez_ad_units.push([[300,250],'growertoday_com-box-4','ezslot_8',107,'0','1'])};__ez_fad_position('div-gpt-ad-growertoday_com-box-4-0_1');.box-4-multi-107{border:none!important;display:block!important;float:none!important;line-height:0;margin-bottom:7px!important;margin-left:auto!important;margin-right:auto!important;margin-top:7px!important;max-width:100%!important;min-height:250px;padding:0;text-align:center!important}. Check the pH levels and make sure they stay between 5.5 and 6.5. When the temperature surpasses 75 degrees Fahrenheit, your lettuce plant will start to flower or bolt. The adequate light duration for lettuce is about 10 to 12 hours. Unlike metal halide and high pressure sodium lights you can position the light close to the plants without burning them. Start small and experiment, you can add more if you like. Asking for help, clarification, or responding to other answers. The type best for your setup will depend on your specific needs. The pH range for seedlings should be adjusted to 6.4 and as your plant matures, the pH should be adjusted to 6.0. This also allows me to grow a larger, slower maturing plant as long as I keep it topped up. You should be able to start harvesting sooner with leaf lettuce. Temperatures that are even slightly lower than this will be helpful for the lettuce at night. Discard the bulbs after 6 months or less, as the spectrum of light your plants need will decrease. Depending on where your hydroponic lettuce comes from, you still may want to wash it. How to Change the Ballast on a Fluorescent Light Fixture, The 11 Best Indoor Garden Systems of 2023, 5 Different Fluorescent Tube Sizes and How to Choose One. The plants dont really grow much in this. You should choose one thats most suited for your plants. It can be totally passive and doesnt need electricity to work. Connect and share knowledge within a single location that is structured and easy to search. If you feel that your plants are growing too slowly, you can up the lighting. Read our. All plants have different light spectrum requirements. By mixing one part Tomato and Vegetable Formula, one part calcium nitrate, and one-half part Epsom salt with pure water, you get a hydroponic fertilizer concentrate that can be diluted and make an incredible nutrient solution. Each type of bulb has pluses and minuses depending on your level of investment in hydroponics and growing needs. If you're going to grow lettuce, consider Bok Choy too. @BRM if you use 80 watt compact fluorescent light (CFL) you don't need a ballast just plug it in normal fitting. Put a few seeds in each planter. This way, you can extend your yields and get great value out of each plant. Place the pots or plugs in the container. Masterblend Complete Combo Kit Fertilizer. The reason you are not finding the answer you are looking for in regards to the lumen requirements of crops is that lumens is a measurement for humans. Which most regular vendors also do not know. I have had excellent indoor results with two T5 fluorescent tubes per 8 heads. For instance, the Kratky method and the wick system are passive and require no pumps or energy to work, while others ensure proper oxygenation and lower the risk of root rot. The theoretically optimal lighting and enough lighting are very different things. Allow for at least 14 to 16 hours of artificial light, followed by 10 to 12 hours of darkness every day for annuals. Lettuce Grow sends . A 40w tube light is definitely not enough either. It is a passive form of DWC, needing no airstones, pumps, or electricity. ). It only takes a minute to sign up. Tip burn is caused by a calcium deficiency.