2022 Eden Green Technology. Here is a picture of the roots in my modified Kratky system. If you buy plants from a garden store you can save several weeks of time. Plenty of water is needed to keep leaves sweet and full. Why does Mister Mxyzptlk need to have a weakness in the comics? I added wicks to each pot. You will want to set your plants in the net pots and backfill around them with hydroton. Manual timers use pins and have two plugs on either side so that you can attach two grow lights at once. Most hydroponic lettuces do best at a pH between 5.5 and 6.0. Red and green varieties are frequent hydroponic favorites and quite attractive on a plate or sandwich. (Optional) Step 4: Add 1.5 grams of sodium benzoate, a preservative, to help your fertilizer last longer. Even with all the answers, there doesn't appear to be a mention of recommended lux/lumen for lettuce. Eunice is an enthusiastic gardener with a passion for growing beautiful flowers. Most light providers don't even know about PAR though, unless they are specialized in photosynthetic light. How much light does Lettuce need per day: Indirect vs. Some of our partners may process your data as a part of their legitimate business interest without asking for consent. The adequate light duration for lettuce is about 10 to 12 hours. . It can be totally passive and doesnt need electricity to work. I also added a wick system to it. Fletcher, I guess you meant 400 to 450nm wavelength for Lettuce? Growing lettuce hydroponically is of great benefits and you can grow any variety of lettuce in your hydroponics system. Heading lettuce takes longer to finish but can be done in about 45 days. Too much more than that (150-200k) and you'll risk having too much which if I recall correctly can cause lettuce to flower (due to the heat concentration). The plants dont really grow much in this. I have had excellent indoor results with two T5 fluorescent tubes per 8 heads. . Poinsettias, strawberries, cauliflower, and chrysanthemums are short-day plants. 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. Generally, you need at least 30 watts of light per square foot of growing space. Mix well. Leafy greens, and lettuce especially, are perfectly suited for hydroponic systems. The appropriate temperature during the day should be from 65 to 70 degrees Fahrenheit. 650 to 700nm is Red and used for flowering and fruit ripping, yes? Lettuce is a great plant to grow indoors, as it doesn't require a lot of light. The Kratky system is the ideal hydroponic system for beginners. Not very practical indoors. It only takes a minute to sign up. All rights reserved. Each of these setups has something to offer. no need to take much care, anyone . Learn More About Our Innovative Hydroponic Greenhouses. The Kratky method uses no pumps or airstones. They grow fast, produce well, and have a small footprint in your grow space. If you happen to have an iPhone, there is an app call KORONA - cut a small piece of 3/4 pvc about 1/2 inch long and super glue a piece of bright white 20lb paper over it to act as a filter. Also you don't need a ballast just a standard screw fitting for the light. Here, well discuss hydroponic lettuce, its benefits, and how to grow it. No matter where you are in your hydroponic journey, lettuce could be the right vegetable for you. Always be sure to find a Kelvin. This powder fertilizer has all of the essential macro and micronutrients that lettuce needs, you just need to add water. Lettuce is one of the most common hydroponic crops because its easy to grow and rapidly reaches maturity. Romaine lettuce. Allow for at least 14 to 16 hours of artificial light, followed by 10 to 12 hours of darkness every day for annuals. This includes keeping the nutrient. You can use starter plugs like Root Riots too. Although natural sunlight is the ideal lighting source for growing plants, artificial lighting for indoor systems can provide a good substitute within the appropriate color spectrum. They don't grow fast as in summer, but they do grow. Because we are only interested in the leaves, bolting is bad for us growers. I will show you how to grow lettuce indoors. You dont need to make any modifications to your Kratky. Examples include rice, eggplant, roses, and corn. Because hydroponic veggies never touch the soil, they arent at risk for these pests and contaminants. How many hours of light does hydroponic lettuce need? The amount and strength of this light determine the taste of your lettuce leaf. Fluorescent lighting does not cost much, power consumption is low, and heat production is minimal. When harvesting this way, you may also want to dispose of some of the leaves near the plants base if they arent as crisp as the rest. WhyFarmIt.com is a participant in the Amazon Services LLC Associates Program. An electronic timer is especially necessary if you are growing a variety of different plants. Preparing a Vegetable Garden Site. How To Keep Cut Flowers Fresh Without Water: Full Guide. You will get a crop sooner this way. What Size Grow Light Do I Need For Two Plants? 1 Artificial lighting for a hydroponic garden should imitate direct and indirect sunlight requirements. If you don't have a sunny window, you . Choosing grow lights for your hydroponic tomatoes Since you'll be growing indoors, you'll need grow lighting. But if youve never grown hydroponic lettuce before, you should know a few things before you purchase lettuce seeds. 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. 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. I planted a mixed pack of leaf lettuce so I have 3 or 4 different kinds. They grow fine. Classic Romaine. Tip burn is caused by a calcium deficiency. The type best for your setup will depend on your specific needs. This light is full of energy and impacts leaf growth that we know as vegetative' or veg' growth.'. This is because nitrogen stimulates foliar growth or leaf growth. It is fine as is. How Many Hours of Light Does Hydroponic Lettuce Need? Average Life Span & Key Care Tips. How many hours of light does hydroponic lettuce need? (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. Fourteen to 16 hours of sunlight is ideal. However, its possible for seeds to be contaminated and carry the contamination through the growth cycle and end up on the final productbut this is unlikely. Each type has its benefits and drawbacks, so it is important to do your research and choose the one best suited for your needs. Incidentally using a CFL light is a great way to start seeds. If you would like to change your settings or withdraw consent at any time, the link to do so is in our privacy policy accessible from our home page.. Two pounds of fertilizer is enough to make 128 gallons of nutrient solution. @BRM if you use 80 watt compact fluorescent light (CFL) you don't need a ballast just plug it in normal fitting. Unlike metal halide and high pressure sodium lights you can position the light close to the plants without burning them. If you want to have a bit of fun you can even add carbon dioxide. So I guess it is in a class of its own. It is the perfect choice if you are just starting out with hydroponics. Now I have bought a Light Meter, to test various lights. To view the purposes they believe they have legitimate interest for, or to object to this data processing use the vendor list link below. If we talk about the natural sunlight, it will be enough for the herb to spend 6 hours in the sun. They can be found in your local hardwa re store if you're lucky. Timers are the least expensive piece of the lighting system, but they are incredibly important. Christina D'Anna is a gardening expert and freelance writer who contributed content to The Spruce in 2013. To get the best out of your hydroponic lettuce, it is best if you grow it in a medium with a PH value of 5.5 to about 6.5. i wouldnt swap out my led for any t5 cfl or metal halide out there for power ppfd/watt light efficiency. Step 1: Pour one gallon of distilled or reverse osmosis water into a clean bucket. 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. The easiest way to maintain a lighting schedule is with an automatic electric timer. Lettuce is a fast growing plant. Set the towel inside a small plastic container with a lid. This can cause your plants to become spindly and leggy. Hydroponic lettuce can last two to four weeks if harvested with the roots intact. Christina has experience in hydroponic gardening methods. Learn tips for creating your most beautiful (and bountiful) garden ever. That is it! All hydroponic lighting systems have four main parts: the bulb, reflector hood, remote ballast, and timer. My hydroponic lettuce has really taken off. [10] 2 Transplant your seedlings to the reservoir. Although you can follow the general guidelines above and have success, some plants do much better with longer or shorter periods of daylight. If you have a mix of these in your garden, you will need to figure out a custom schedule. Commercial growers across the world produce millions and millions of dollars of the stuff each year. Usually, it takes about 3 weeks for the first edible leaf to emerge and about 45 to 85 days to get the full head harvest. Lettuce Grow sends . The nice thing about leaf crops (which lettuce is) as opposed to fruit crops (like tomatoes that have to flower to produce the part you want) is that as long as you can keep it alive it doesn't really matter how big or vigorous it grows, you can just grow more of them. Lettuce is a low-light plant and it won't do well in full sun. Some people say 16-18 hours a day because that is how much light they get outdoors. How long does lettuce take to grow in hydroponics? Lettuces are a cool-weather plant. The right measure would be lumens, or PAR and I tried with 2x 900 lumens and that wasn't enough either. I am, however, keeping the lights on longer than others here with their brighter lights (only giving about five hours' darkness or less). But I wanted to be able to top my reservoir up and adding airstones allows me to do this. Normally you fill the container at the start and when the water runs out the grow is done. How much energy does it take to grow lettuce? They include wheat, lettuce, potatoes, spinach, and turnips. Lettuce, for example, prefers a range high in blue light. . Getting the separate ingredients in bulk and measuring and mixing yourself will save you loads of money long-term and give you the most flexibility when it comes to plant nutrition. You can just set up a simple Kratky lettuce grow or you can adopt some of my modifications if you want something a bit more complicated. When you think hydroponics, the first vegetable that comes to mind is probably. Check the pH levels and make sure they stay between 5.5 and 6.5. 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. Lettuces, in particular, are highly susceptible to dangers like e.coli. Start growing hydroponic lettuce indoors with the Kratky method. The reflector hood is a reflective casing around the bulb. Think of it like filling a jug of water. Put it in a warm place for a few days. But eventually, over time the plant will go to seed or become bitter. I have been to many hydroponics stores and seen almost all the lettuce hydroponics videos on youtube. How many hours of light does hydroponic lettuce need? During summer, lettuce does not grow that fast, but it does grow.if(typeof ez_ad_units!='undefined'){ez_ad_units.push([[300,250],'growertoday_com-medrectangle-4','ezslot_1',106,'0','0'])};__ez_fad_position('div-gpt-ad-growertoday_com-medrectangle-4-0');if(typeof ez_ad_units!='undefined'){ez_ad_units.push([[300,250],'growertoday_com-medrectangle-4','ezslot_2',106,'0','1'])};__ez_fad_position('div-gpt-ad-growertoday_com-medrectangle-4-0_1');.medrectangle-4-multi-106{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}, Lettuce does not require much light. Here are our suggestions for the best types of lettuce for hydroponic growers: Butterhead lettuce offers a velvety texture and a buttery taste. Another great thing about lettuce is that it grows well in tandem with other leafy vegetables and herbs. It flourishes under growth chamber conditions. Artificial lighting for a hydroponic garden should imitate the direct and indirect sunlight requirements for outdoor gardening. "High humidity also favors the physiological disorder tip burn. In fact, many growers remove the entire plant, root system and all, to prepare it for retail sale. Here are the steps you can follow to build your hydroponic system: Several parts determine the efficiency of a grow light. Given too little light, the plants won't grow as efficiently, while too . Use A Good Nutrient Solution. Unfold the paper towel to check on them. And fluorescent light works best as it is of a reasonable cost, especially if you are a beginner and are only trying out. How much lighting do I need for growing lettuce using indoor hydroponics? In general, your NPK levels should be as follows: Nitrogen: keep the nitrogen level at approximately 5. Hydroponic lettuce growing with indoor lighting. The color of your lettuce may impact your light requirements. Lettuce plants grown in hydroponics are fast and easy to maintain. How much light does a scented oak fern need? Luckily, hydroponic growers dont need to be scientists to get the right lighting. Fruiting plants like tomatoes and peppers like a spectrum high in red light. This means 5+ hours of sunlight hitting the plant leaves is recommended for growing lettuce and other leafy greens. Darkness is as vital as light for plantsthey need time to rest and metabolize food, just like animals. Outdoors, the lettuce can be placed in a sunny spot in the garden or on a patio. Source: Rural Living Lettuce requires roughly 10-12 hours of light per day. 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. If you start plants with seeds it will take a few weeks longer than starting with transplants. But I decided to hot rod it a bit by adding airstones. This post contains affiliate links. Manage Settings Neither is needed but I think there is an advantage to adding airstones. During the day, lettuce seeds require an average of 18 hours of light and six hours of darkness to grow properly. You can start your seeds in a damp paper towel by folding them over. Lettuce seedlings need around 18 hours of light during the day and six hours of darkness overnight to mimic outdoor conditions. DLI is calculated by measuring the photosynthetic photon flux density, which is how much light within the wavelength that plants need. Otherwise, you are just guessing. Depending on your setup and bulb type, you may need to reduce the amount of light you give your plants. How much lightning is needed for water spinach and celery? Place the pots or plugs in the container. There isnt anything tricky or fancy about growing lettuce, and you can get started with almost no experience and very little money. Stack Exchange network consists of 181 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers. 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. Its an incredibly versatile leaf with plenty of uses, and a hydroponic environment is a perfect setting to ward off contaminants. Read our. This is simply because the lettuce may have been handled by someone with unclean hands. This also allows me to grow a larger, slower maturing plant as long as I keep it topped up. 4Wonderful GiftThe hydroponic growing kit is easy to assemble and easy to use. Because of their large, flexible leaves, these plants are an excellent choice for salads, sandwiches, and lettuce wraps. The short-day cycle mimics natures environment for plants that flower in the spring. Check Price at Amazon . You can grow just about anything in a hydroponic greenhouse, but it's important to choose plants that will do well in water. Its a good source of vitamin K, essential for bone strength. To grow hydroponically, you need plants, a container, water, a way to anchor the plants, nutrients and a light source. Gardening & Landscaping Stack Exchange is a question and answer site for gardeners and landscapers. This package includes a 4-18-38 Tomato and Vegetable Formula, 15.5-0-0 calcium nitrate fertilizer, and Epsom salt. Depending on the lights you use and your particular setup, you may need to bump this up or down. 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. Browse other questions tagged, Start here for a quick overview of the site, Detailed answers to any questions you might have, Discuss the workings and policies of this site. In general, most hydroponic leafy greens offer 11-13 harvests per year with the right greenhouse conditions. You can even notice a difference in flavor in lettuce that is harvested early in the cool morning, and late in the afternoon when the sun is out. Does Counterspell prevent from any further spells being cast on a given turn? How much is this exactly? Mix well. For most varieties, you can have fresh, healthy leaves ready to harvest within six to eight weeks. If you go larger they will fall through. Cookies collect information about your preferences and your devices and are used to make the site work as you expect it to, to understand how you interact with the site, and to show advertisements that are targeted to your interests. They are cheap and easy. Temperature Lettuce does well in cooler temperatures. So be assured of ready available nutritious leafy green at your disposal. Lettuce does well in cooler temperatures. Plants grown under lights indoors need more hours of light than the same plants do outdoors. Some varieties can take longer to mature. That's a big number. In general, lettuce should germinate in temperatures between 65 and 80F. But they also go to seed with long daylight hours. Use 1, 23W CFL (100W equalivant), 6500K bulb per plant. In a bottle combine yeast sugar and water make a hole in the cap, connect a pipe from the bottle to a glass of water make sure the pipe connected to the bottle is air tight. "After the incident", I started to be more careful not to trip over things. Ballasts are sometimes sold as a part of the lamp assembly, but these are usually far too hot and heavy. One reader pointed out that with the addition of airstones it now would be considered DWC. It amazing how easy it is to start seeds (even temperamental varieties) with CFL light and a heating mat. Beginners often take up hydroponics because they want to grow their food but dont have access to outdoor space. 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. If you remove the large, outermost leaves and keep the rest of the plant intact, the head will continue to pump out new leaves. I'm trying to figure out the costs involved with the electricity of the lights. University of New Hampshire Extension. Start your seeds in jiffy pellets or starter plugs. There are a lot of different varieties and colors to choose from. Are you thinking about growing hydroponic lettuce indoors? The texture is crisp, and the flavor is slightly sweet. Since theyre delicious and versatile, theyre also perfect for your hydroponic farm. Also, the soil itself may be present on the plant, which no one wants to eat. The right measure would be lumens, or PAR and I tried with 2x 900 lumens and that wasn't enough either. Some types may be better than others, or more efficient. In my answer there is a link, you can pick up a CFL for like $30. Discard the bulbs after 6 months or less, as the spectrum of light your plants need will decrease. When you visit the site, Dotdash Meredith and its partners may store or retrieve information on your browser, mostly in the form of cookies. A lot of commercial lettuce is grown this way. The net pots are not a full 3 inches so you want to use a 2 7/8 hole saw. What Types of Plants Can Grow in a Hydroponic Garden? Depending on where your hydroponic lettuce comes from, you still may want to wash it. Budget: A total of 306.72 kWh of energy was used growing lettuce hydroponically with 48 LED lighting fixtures on for 18 hours each day. To learn more, read our guide to hydroponic romaine lettuce. So I am growing my hydroponic lettuce in a 10 gallon tote but you can use one smaller or larger. The intensity of the grow light is important for ensuring that the plants receive enough light to grow properly. All hydro lighting systems have four main parts: the bulb, reflector hood, remote ballast, and timer. Once established, you can lower the temperature slightly, keeping it around 55F at night and 75F during the day. An electric timer allows you to take care of this hassle-free and change it according to your needs as your garden evolves. This brings our total to 330 kWh = 1.2 GJ = 1,200 MJ of primary energy required to produce 1 kg of lettuce. A laser temperature gun can help determine if the intensity is resulting in too much heat. Growing lettuce needs full sun exposure for at least 6 h per day. You can keep these light features in mind when choosing a grow light: All plants have different light spectrum requirements. Make sure to provide the lettuce plants with about 10 to 14 hours of fluorescent lighting every day. You might have to adjust the size of your grow light. I recommend using hydroponic nutrients to feed your lettuce plants. Next, a lack of water will cause bitterness. The required pH for hydroponic lettuce ranges from 5.6 to 6.2. If you wanted to grow tomatoes in this system you would need to grow them in a trash can. With a sweet yet nutty flavor and a buttery, soft texture, oak leaf lettuce is always a favorite. This technique is called cut and come again. Using cut and come again, you can have fresh salads every day without the wasted time and energy of constantly replanting heads of lettuce from seed. Double check the pH level of your system approximately 15 to 30 minutes after adding nutrients. 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. 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. They can be grown all year round in a controlled environment. It doesnt have to be dark. Others, like Iceberg and denser, sturdier lettuces, are ready to harvest in six to eight weeks. Your lettuce plants prefer a stable pH level of 5.5 to 6.0, in most hydroponic growing systems. With some aeration, the air roots wont be damaged because they can breathe even if partially submerged. Grow greens, herbs, vegetables and fruit all year long When the temperature surpasses 75 degrees Fahrenheit, your lettuce plant will start to flower or bolt. 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. Luckily, hydroponic growers dont need to be scientists to get the right lighting. Consider the size of the area you want to cover with the grow light and choose a light that can do this. They are small and you want to make sure each planter has at least one healthy plant. Buttercrunch makes small loose heads and is a good crop to grow. How Much Light Does Lettuce Need to Grow Indoors? Since its up to 95% water, it can have a hydrating effect, and its vitamin A is good for the eyes. You can use a pH test kit. The Spruce uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Connect and share knowledge within a single location that is structured and easy to search. Once your greenhouse is built, you'll need to add the plants. Its requirements are not too hard and it is one of the easiest plants to grow hydroponically. If you're going to grow lettuce, consider Bok Choy too. Watch giraffes eat our delicious hydroponic lettuce! 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?). If you are growing your lettuce indoors, place it near a south-facing window. Also, keep on top of potassium, magnesium, and phosphorus levels to keep your plants healthy. You will need a large container like a tub or barrel for the nutrient solution. Each type of bulb has pluses and minuses depending on your level of investment in hydroponics and growing needs. If you use fluorescent tube or CFL lights, I have used both, you should aim for about 1500-2000+ lumens per square ft. with a Kelvin rating of 6500K. Just use a red:blue ratio of 5:2 and you'll find that works best. If you arent controlling the temperature that your lettuce is grown in, you need to work with the sun or accept the occasional bitter head of lettuce. Forgetting to stratify seeds. You can use perlite too or even gravel as long as it is clean but hydroton or growstones work best. 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. But I think its overkill. In hydroponics, light, temperature, water, and nutrition are all controlled to a T, so theres nothing to hold your lettuce back. Hydroponic Lettuce Growing Light Requirements, Types Of Low Light Lettuce Grown In Hydroponic. Anyway, I'll probably get more and different lights in February, and update this post, but probably not before then. Growing lettuce needs full sun exposure for at least 6 h per day. That said, its still essential to understand the proper conditions for optimal growth. You will want a 2 7/8 hole saw, otherwise you will need to trace out the holes and cut them out with a razor knife. You can spend money for the grow bulbs but I would not bother at this point. The most common types of bulbs are LED, fluorescent, metal halide (MH), and high-pressure sodium (HPS). Lettuce doesn't demand a lot of light, so start with anywhere from 10 to 14 hours of moderate to low light each day. The long-day cycle mimics the natural environment of summer-flowering plants. Put a few seeds in each planter. 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. It is based on the level of light that we can perceive. Dont try to start your seeds in soil because you dont want loose dirt falling into the reservoir. if(typeof ez_ad_units!='undefined'){ez_ad_units.push([[300,250],'growertoday_com-large-leaderboard-2','ezslot_12',114,'0','0'])};__ez_fad_position('div-gpt-ad-growertoday_com-large-leaderboard-2-0');if(typeof ez_ad_units!='undefined'){ez_ad_units.push([[300,250],'growertoday_com-large-leaderboard-2','ezslot_13',114,'0','1'])};__ez_fad_position('div-gpt-ad-growertoday_com-large-leaderboard-2-0_1');.large-leaderboard-2-multi-114{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}. Its not just about the time that the faucet is on, but how much water is coming out. 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. How long does lettuce take to grow hydroponically? They also get some window light. Its measured in units called micromoles (mols) for light wavelength that is usable by your plant. All plants have different light spectrum requirements. Anything else lettuce might grow but it will be elongated and not form proper lettuce heads.