Urban and Vertical Agriculture

Plants need light, water and nutrients in the right balance. Too little or too much of any one causes poor growth. Measuring each lets you improve them.

• Light is measured in hours per day, and leaf crops such as lettuce usually do well with about 12 hours.
• Water should reach the roots without pooling, and you track the litres used each day.
• Nutrients are fed in a balanced mix, and the strength is checked with a simple meter or test.
• Indoor lights use power, so a 30 W light on for 12 hours uses 0.36 kWh each day.
• A common mistake is to add more nutrients when plants look poor, when the real cause is too little light.

Activity. Survey your growing space and record the light hours, the space size in square metres and the water source, then estimate the power use if you add a light.

Standard to meet. Record measurements and units in your survey, and calculate your power estimate correctly.

The best crops for a small space are fast, compact and in demand. You match the crop to your light, your season and your buyers. Fit the growing time to your 45-day run.

• Prefer leaf crops and herbs, because they grow quickly and need less depth for roots.
• Check the days to harvest on the seed packet and make sure it fits your 45-day window.
• Choose crops that suit your light and temperature, and avoid ones that need a lot of space or support.
• Ask two possible buyers which crops they would actually buy.
• A common mistake is to pick a crop because it is fashionable and not because it fits the space.

Activity. Pick two crops, write the days to harvest, the space each needs and your reasons, and ask two buyers for their view.

Standard to meet. Choose two crops that both fit the growing window, each with at least one reason supported by a buyer comment or a measurement.

The system holds the plants, water and light. Good design saves space and water, and stops problems such as rot. You build it safely and document it.

• Choose containers or racks that are stable, food-safe and the right depth for your crop.
• Include drainage holes and a tray so water drains away from the roots and can be reused.
• Place lights at the right height and on a timer, and keep electrical parts dry and away from water.
• Photograph and sketch the system and label the parts with their sizes.
• Check with your local authority about rules for balconies, rooftops and electrical work.

Activity. Build your system, test it with plain water for a day, and submit photos, a sketch and a list of parts with sizes.

Standard to meet. Build a system that holds water without leaks and drains properly, and add a sketch with labelled measurements.

Plants need regular care. A simple routine for water, feeding and pest checks prevents most problems. A daily log gives you the data for later.

• Water on a schedule and record the litres used each day.
• Check the pH of the nutrient mix each week and keep it in the range for the crop, often about 5.8 to 6.5.
• Look at the leaves for spots, holes or insects every day, and remove affected leaves.
• Write the date, litres, pH and any problem in the daily log.
• A common mistake is to water by habit and not by checking the plant and the mix.

Activity. Run your system for 45 days and submit the daily log with water, pH checks and any pest or problem notes.

Standard to meet. Complete your log for at least 40 of the 45 days and record an action for any out-of-range reading.

Yield is how much food you get from the space you use. You weigh the harvest and compare it with the area and the water used. These numbers tell you if the system is good.

• Weigh each harvest on a kitchen scale and record the kilograms and date.
• Calculate yield per square metre as the total weight divided by the growing area.
• Calculate water per kilo as the total litres used divided by the total kilograms harvested.
• Compare your numbers with another crop or with an earlier harvest to see changes.
• A common mistake is to weigh only the best plants.

Activity. Weigh all harvests, calculate yield per square metre and water per kilo, and present them in a table with one chart.

Standard to meet. Calculate correctly with units, and show the totals clearly in the chart.

To know whether growing pays you must add up every cost. Indoor systems use power, so include it. The cost per kilo is the key number.

• List the cost of seeds, nutrients, power, containers share and your time.
• Spread the cost of long-lasting items, such as racks, over the harvests you expect.
• Add all costs and divide by the kilograms harvested to get the cost per kilo.
• Compare your cost per kilo with the price you can sell at to find the margin.
• A common mistake is to leave out power and labour.

Activity. Complete a cost sheet showing every cost, total, kilograms and cost per kilo.

Standard to meet. Calculate your cost per kilo correctly and back each cost line with a note, receipt or measurement.

Fresh produce sells best when it is clean, cool and local. You handle it hygienically and keep records. Sharing with neighbours builds community.

• Harvest in the cool of the day, wash with clean water and dry the produce gently.
• Pack in clean containers, keep it cool and label it with the name, the date and your contact.
• Sell close by, such as to neighbours or a nearby shop, to keep it fresh and the transport short.
• Record each sale with the date, weight and price, and keep a small amount to share.
• Check with your local authority about the rules for selling or giving away food.

Activity. Sell or share your produce, keep a record of each sale and calculate your margin per kilo.

Standard to meet. Complete your sales record, calculate your margin correctly, and handle and label the food as your local authority requires.

The review decides whether to scale up, change or stop. Use your numbers on yield, cost and demand. Write the decision down with reasons.

• Compare yield, water use and cost with your targets and with the earlier numbers.
• Note the main lessons, such as what plants did best and what problems recurred.
• Estimate the benefit and cost of adding more space, using your cost per kilo and margin.
• Decide to scale, change or stop and set a date for the next step.
• A common mistake is to scale up before the numbers show it will pay.

Activity. Present a review with your results table, lessons and a scale, change or stop decision with reasons.

Standard to meet. Support your decision with at least three numbers from your records and include a date for the next step.