Salad greens are an easy, low-maintenance crop to harvest multiple times weekly in a family greenhouse, yielding 5-6 ounce harvests on average. To optimize yield and meet weekly market needs, grow greens on a 30-by-96-foot production area, stagger harvest schedules accordingly and stagger their harvesting cycles to meet market needs.
Hydroponics
Hydroponics refers to growing plants without soil; also referred to as solution culture and used extensively in greenhouse vegetable production in developed countries, it serves as the cornerstone for most greenhouse vegetable production in these nations. Plant roots are planted into inert compounds like vermiculite, rockwool or clay pellets which won’t introduce new elements into the environment and then fed nutrient-enriched water for feeding purposes. Hydroponics allows more plants to be grown per square foot while less wasteful chemicals are released into the environment while more precise controls allow better levels and quicker growth rates overall.
Hydroponics offers leafy green growers an appealing solution, as it enables year-round production despite weather or climate conditions. This enables producers to meet consumer demand for fresh, premium leafy greens while mitigating issues in their supply chains caused by food safety, disease or extreme temperatures.
Recent food poisoning outbreaks have highlighted the necessity of new solutions that provide safe and healthy leafy green crops. Due to being consumed raw, leafy greens increase their susceptibility to pathogenic organisms; any subsequent health issues caused by contamination could affect consumer trust in salad industries leading to decreased consumption rates.
Although hydroponic lettuce cultivation may seem straightforward, there can be numerous challenges associated with growing it this way. Reaching the appropriate pH balance of your nutrient solution – between 5.2 and 6.8 for optimal plant development – is crucial. Nutrient solution delivery methods such as drip, ebb and flow, immersion or any other means should also be considered when formulating the recipe for success.
Hydroponic systems also need an adequate source of dissolved oxygen for their plants to flourish. There are various systems available for providing this source, including non-circulating systems which eliminate the need for pumps; or the Bokit, developed by Levo which uses a reservoir to trap oxygen inside itself.
Routine testing of tissue and nutrient solutions is also an integral component of success for smaller growers; however, due to limited resources or economic limitations this can sometimes prove challenging.
Aeroponics
As is true of all food production, efficiency is key to salad farming’s success. Salad farming differs from other vegetable crops in that its product sells by weight rather than head, and therefore yield per square foot is essential for profitability – particularly considering higher production costs associated with greenhouse production.
Aeroponics differs significantly from hydroponics in that, instead of submerging plant roots into nutrient rich water, aeroponics suspends their entire plant in air with misted nutrients continuously being applied, providing increased access to oxygen and other atmospheric gases which boost growth rates significantly.
Though aeroponics provides clear benefits, its implementation in large scale commercial operations is far from straightforward. One of the primary difficulties associated with aeroponics lies in keeping water nutrient concentration within precise parameters; any deviation could result in catastrophic crop yield losses. Furthermore, maintenance requirements associated with spraying nutrient rich mist over your plants is high as well as difficulty in clearing clogged mist nozzles quickly enough.
To overcome these hurdles, some growers have turned to nozzleless aeroponics systems that utilize small water droplets instead of nozzles to create mist and deliver it into their environment. This reduces water consumption as well as the risk of clogged nozzles.
Aeroponics salad production systems may lead to an explosion of fresh salad production globally. At a time when many are seeking solutions for health and climate crises, these farms offer healthy options.
One such trend can be seen with the salad farm GP Solutions who provides modular, stackable and mobile farms built within shipping containers as well as the Greenery S hydroponic system and Farmhand software for farming automation. Another example is Gotham Greens who has created a hybrid approach to vertical farming that currently operates multiple farms throughout major US cities with support from McCain Foods’ deep food industry expertise and with their partnership proving the power of collaboration to achieve their shared vision.
NFT (Nutrient Film Technique)
NFT hydroponics utilizes a thin film of nutrient solution which constantly flows over plant roots. This system dispenses with soil, enabling plants to directly access essential nutrients from their solution source and increasing yield while simultaneously minimizing water usage – creating an extremely efficient production method.
NFT cultivation of leafy greens such as lettuce (Lactuca sativa), spinach, kale and arugula makes good use of NFT’s shallow root systems to maximize production quality while simultaneously reducing labor requirements and maintaining high-quality production. Herbs such as basil, cilantro and parsley also often opt for this form of cultivation due to its constant flow of nutrient solution; making NFT an efficient method that ensures quality output with reduced labor needs and maintaining consistent, reliable results.
NFT cultivation systems offer year-round cultivation opportunities as they can withstand even extreme climates, being indoor-operable makes NFT invaluable in areas with limited land or resources. Furthermore, urban agriculture initiatives benefit greatly from NFT systems as it allows vertical farming that maximizes space utilization.
NFT systems consist of long, shallow channels made of food-grade plastic and often insulated to maintain an even temperature in the water. On top of these channels are floating rafts or net pots with holes designed to hold plant seedlings – these holes may be adjusted depending on what’s being grown.
A water pump ensures continuous delivery of nutrient solution through channels, while sensors monitor pH and fertility levels. If necessary, dosing systems can inject fertilizer or other chemicals directly into the solution before it returns to rafts – an easy system to set up and manage that provides reliable yet low maintenance cultivation solutions.
An NFT system can be enhanced with an air stone and pump that help aerate and oxygenate its nutrient solution, providing access for roots to access oxygen necessary for photosynthesis, thus avoiding suffocation. Aeration also plays a vital role in minimizing stagnant water pockets that could harbor pathogens.
Deep Flow Technique
A variation on NFT, this system employs floating rafts made of food-grade plastic for growing leafy greens. They may even be insulated to maintain an even temperature for the nutrients solution, holding plants securely by capillary action and net pots on their top surfaces while roots reach down into it to absorb vital nutrients from below the water surface. These floating rafts make harvesting quick and are easily cleaned between crops – ideal for rapid cultivation cycles!
Rafts are usually connected to collection pipes that lead back to a nutrient reservoir – such as a recirculating pond or raceway – for collection. Each raft also contains holes for aeration tubes that keep the solution fresh and oxygenated; this ensures proper drainage, while preventing buildup of nutrients in the system. This method works best for plants with small root systems like romaine and butterhead lettuce, though with some modifications (i.e. stronger rafts and additional space), it could also be used successfully for salad greens like kale or even cooking greens grown for production.
Hydroponic systems with floating substrate differ from NFT or DWC in that their roots remain at the surface, rather than submersion below waterline. This creates more of a barrier against air, but could mean plants dry out more quickly should flow stop or their nutrient solution becomes unclean.
To avoid this situation, growers should employ high-grade nutrients in their growing mix and keep pH and EC within acceptable ranges for leafy greens. A solution meter will make this task simpler.
To reduce these issues, growers can utilize an ebb-and-flood system which floods rafts with the nutrient solution before draining it off again, raising and lowering nutrient levels repeatedly to allow roots to take in oxygen they require for healthy roots growth. It’s a reliable system which works well across many different kinds of greens.
