From Seed to Shelf
Image Credit: G's Fresh
Seed
A seed is a plant embryo and food reserve that is covered by one or more protective outer layers or coats. The seed germinates and sprouts the first shoots and roots.
The first shoot uses the seeds food store until it has sufficient seed leaves and proper leaves to feed itself through photosynthesis, a process that takes a few days. The shoots go on to become the plant itself. All leafy salads are grown from seed.
Image Credit: G's Fresh
Image Credit: Hazera Seeds UK Ltd
With a growing world population and a finite amount of agricultural land to feed people, a lot of work goes into researching and developing the seeds we need to live on.
Seeds are bred to produce healthy crops and to deliver the optimum number of plants for the growing space and conditions. Where possible seeds are also bred to be resistant to disease or pests and better suited to growing regions, seasons and weather.
Developing new seed varieties takes different time depending on the crop. For example, radishes grow from seed to full mature plant in about 28 days, so it is possible to grow several crops in a season. The short growth cycle makes it easier to introduce and test variations. By contrast crops that are harvested from trees, such as avocados or apples may only have one crop a season. The fruit bearing plants may can take years to grow to produce fruit so developing new varieties takes much longer.
Once the seed is harvested from the parent plants, it needs to be cleaned and graded. Because it is produced in the natural world, seed can be different sizes and can come into contact with all sorts of microscopic organisms, moisture and dust. All these factors may affect whether or not the seed grows into a healthy plant, fit to be harvested.
Image Credit: Syngenta
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Image Credit: East Coast Growers
The seed also needs to be able to be used by farmers in machinery specifically designed to sow the crop in the field. In some crops, seed that blocks up the tubes on a seed drilling machine, failure of the seed to germinate and plants that grow with contaminants on them - all these factors mean that the grower produces less crop than planned.
To make sure that the seed is healthy, clean and one of a kind (growers don’t want a cauliflower and carrots in their lettuce field.), all the seed is carefully screened and cleaned to be bagged up and sent to the plant nurseries.
Some seeds are drilled direct into the field, but many salads are grown from seed in greenhouses before they are planted in the field.
Sustainably produce blocking peat is mixed and then moulded into moist blocks for each seed. When the timing has been agreed with the grower, the trays of peat blocks are sown with seed and the seed is covered, often with sand, and the required fertiliser.
Image Credit: G's Fresh
Image Credit: G's Fresh
The trays of sown seed are put in a temperature controlled germination room to start the growing process. Once the seeds have germinated and plants have appeared, the trays are transferred to greenhouses at a rate of 2,000 trays/300,000+ plants per hour. The plants continue growing until they are robust enough and needed by the grower for planting. The grower plans the planting based on factors such as prevailing weather, soil condition, and the growing/supply plan agreed with the retail or wholesale customer.
The British climate is well suited to salad production between May and October. Leafy salads like an even temperature range and grow well between 12° and 18° centigrade.
They grow steadily and fairly quickly [compared to other plants] in good quality soil with just the right amount of moisture. Many salad producers are in coastal areas around the UK as the breeze keeps the temperature lower than inland. Wholehead lettuce grown from seedling to maturity in 6 – 8 weeks when the weather is just right. They can take up to 10 weeks at the start and the end of the UK season.
When the temperature is too hot for leafy salads they may do one of 3 things – the first is that above 25°C they bolt. The plant changes its priority from producing leaves and instead attempts to produce seeds. A lettuce may grow taller and outer leaves will start to brown. The second is that a lettuce may try to hang onto its water. The lettuce becomes dense taking all the water to the centre of the plant and using the outer leaves to act as insulation. Finally, if it is too hot (or wet, or cold) the plant just calls it a day and dies.
Image Credit: David Norman
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Image Credit: East Coast Growers
Outdoor Growing
A lot of work goes into preparing the soil before planting.
Having ploughed in or removed weeds, the soils is tilled and made level to create an even seedbed. This process incorporates the organic matter into the soil to improve fertility.
The land levelling process ensures that the water distribution for the crop will be even as possible. If there is a slope in a field, the plants at the top of the slope may fail because the water runs away from their roots. The plants at the bottom of the slope may rot because the soil is boggy and their roots are too wet.
The peat blocks are planted a set distance apart from each other. This gives the plants room to grow. By the time they are ready to be harvested the field is a green carpet of plants with only the tractor wheeling’s (the tracks where the tractor drives) as gaps.
In the early weeks of the crop, the farmers and their teams walk the crop daily to check the plants’ progress.
Depending on the time of year the crop can be covered for with different kinds of protection.
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To protect early season crop and encourage it to grow faster the crop is covered in fleece. This is a man-made fibre designed to retain some heat and still allow airflow to the crop. This is generally applied from Mid-February to April. This also protects the crop from birds and insects
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As ambient temperatures rise, we must stop using fleece as this starts to retain too much heat and can stress and damage the crop. During the summer to help protect crops until the plants are big enough, they can be covered with long carpets of fine mesh. This can be a wider net to protect from birds or a finer insect net. The nets are laid over the crop which prevents the birds/insects from reaching the leaves and allows water and ventilation to reach the crop.
Once the crop is established, the growers will check the crop each week for damage by weather, pests or disease.
Depending on weather conditions, outdoor wholehead and speciality lettuce take 7-10 weeks to grow to maturity. Babyleaf crops take anything 3-9 weeks to be ready for harvest.
Image Credit: G's Fresh
The job of producing food demands a holistic approach. Many growers take an integrated crop or farm management approach to growing crops. In short this will include some or all of the following:
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Crop health and protection
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Soil management and fertility
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Water management
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Energy use
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Biodiversity and Environmental stewardship
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Community engagement
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Logistics
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Weather and climate monitoring
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Risk assessment
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Business management and profitability
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Stakeholder management
Image Credit: David Norman
All salad crops supplied to UK retailers, processors and markets must be grown to set standards to demonstrate compliance to food safety, quality, and environmental protection.
Red Tractor is the industry standard assurance scheme for all customers in the UK along with GLOBALGAP. However, there are also other assurance schemes depending on customer requirements, e.g.
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Linking Environment & Farming (LEAF)
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Select Farm
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GRASP
Image Credit: Natures Way Foods
Indoor Growing
Indoor lettuce farming in the UK is transforming how we grow fresh, local produce all year round.
By bringing cultivation indoors, growers can control temperature, light, and humidity to create optimal growing conditions - whatever the weather outside.
These innovative systems are helping the UK lead the way in sustainable, efficient food production—bringing fresher, greener salads from farm to fork.
Image Credit: Agrial Fresh Produce
Soil-Based
Soil-Based Systems use traditional growing methods in protected environments such as glasshouses or polytunnels. These offer natural flavour development while reducing the risk of weather-related crop losses.
Hydroponic
Hydroponic Systems grow lettuce without soil, using nutrient-rich water to feed the plants directly. This method conserves water and accelerates growth, making it ideal for consistent, high-quality yields.
Vertical Farms
Vertical Farms stack plants in layers under LED lighting in climate-controlled environments. Often combined with hydroponics, this high-tech method uses minimal space and resources, allowing lettuce to be grown in urban areas close to consumers.
Image Credit: Agrial Fresh Produce
Harvest
The timing of the harvests during the season depend on a number of factors. Crops are planted to a schedule agreed with customers so that supermarket shelves have a steady supply of products throughout the year.
Because salads are a natural product with a short shelf life, timing is everything. When everything goes to plan, the crop leaves the field and reaches supermarket shelves 24 – 36 hours after harvest. Factors that affect the harvest include the following:
Wet
If the weather is too wet, the harvesters may not be able to get into the field because the ground is too soft. Wet weather also makes the crops soggy and this can reduce shelf life. Finally, shoppers are less likely to buy salads when the weather is wet so demand drops which can delay the harvest for a short time.
Cold
If the weather is cold, shopper demand also falls as we buy products like soup instead. A sustained period of cold weather may also slow down the growth of the crop. If the crop grows more slowly, it may not be ready in the harvest window that has been agreed.
Warm
When the weather is warm the growers face different challenges. First of all, when the temperature is between 20°C and 25°C UK salad consumption rises by about 10%. And if a British summer stays over 25°C for any length of time, demand for salads can increase by up to 40%. Higher demand means that growers must be ready to supply more product for a short period. In warm weather the crop may also mature faster leading to a glut of product.
Hot
While the hot weather seems like a good thing for salad sales, it isn’t always brilliant for the plants themselves. Leafy salads like an even temperature range and grow well between 12° and 18°C. Once the temperature is over 20°C the plants start thinking about redirecting their energy into seed production. They also need more water. Between 25°C and 30°C while shoppers can get enough of salad, the plants themselves stop growing which can make meeting demand a bit tricky.
Image Credit: G's Fresh
Wholehead salads are harvested by hand. A long knife is used to cut the lettuce at ground level. Outer leaves are discarded in the field and eventually are turned back into the soil as organic matter.
Each lettuce is weighed and wrapped on the harvest rig. The rig is a big tractor controlled by the harvesters. It travels at a slow walking pace. The harvest crew of up to 8 people walk in front of the tractor under a canopy so they are protected from the sun, wind or rain. As they harvest each head, they place the lettuce on a conveyor belt that runs onto a platform the back of the rig. Here other team members examine each head to ensure that each lettuce meets the required quality standards.
Image Credit: Agrial Fresh Produce
The boxes of product are transferred to a trailer and chilled to 3°C within 3 hours. The product in the field is around 16°C. On a hot day it can be up to 26°C. Lowering the product’s temperature, removes this field heat and significantly improves product’s shelf life.
Baby leaf products are harvested by specialised machines that cut between 2 and 3 tonnes or crops like spinach, rocket or lambs’ lettuce per hour. The cutting blades are similar to several sets of horizontal shears that snip the thin stems just above the soil. The baby leaves are fed gently onto a conveyor belt into hoppers. These hoppers are then taken either to be packed or, in some cases, washed and then packed in either solo packs [1 product] or mixed packs [2 or more products].
Image Credit: Natures Way Foods
Processing
Our UK packed bagged salads follow a fully integrated supply chain designed for freshness, efficiency, and sustainability. It all begins with our growers carefully cultivating lettuce varieties tailored for taste and texture.
Because leafy salads are grown and live in the field until harvest, they have a limited shelf life. Once harvested at peak freshness, the leaves are swiftly transported to nearby state-of-the-art factories.
In the factory, the salads undergo a meticulous process: they are washed in chilled, purified water, gently dried, and packed in protective, breathable film to maintain quality and shelf life. Automated systems and strict food safety controls ensure consistency and hygiene every step of the way. To make sure shoppers receive products of the highest possible quality, leafy salads are moved to distribution within hours of being picked. This temperature-controlled process begins in the field, where the lettuce is quickly cooled to 3°C.
Distribution
Once the temperature has been reduced, refrigerated trucks transport the leafy salads to retail and wholesale regional distribution centre chiller rooms.
From these warehouses, the products are then distributed to individual stores or wholesale markets, ensuring they arrive fresh and ready for sale.
