Greenhouse, Hydroponic and Vertical Farming Guides

How greenhouses, hydroponics and vertical farms fit together

These three terms get used as if they were alternatives, but they describe different things. A greenhouse is a building that lets sunlight in and holds heat. A vertical farm is an indoor space, often a warehouse or shipping container, where crops grow in stacked layers under LED lights with no sunlight at all. Hydroponics is a way of growing without soil, with roots fed by a nutrient solution, and it can be used in either one.

So hydroponic vertical farming means stacked, soilless growing under artificial light, while a hydroponic greenhouse grows in a single layer (or on tall vines) under natural light, usually with supplemental lighting in winter. A vertical greenhouse sits in between: racks or towers inside a glass or poly house, which raises output per square foot while still using the sun. All of them fall under controlled environment agriculture (CEA), where the grower manages temperature, humidity, light and nutrients instead of the weather doing it.

Hydroponic growing systems compared

The system you pick decides how much you’ll spend on equipment, how forgiving the setup is when something fails, and which crops it suits. Most hydroponic farms use one of these:

Recirculating systems use far less water than soil growing, because the solution goes back to the tank instead of draining away, but they also spread root disease faster when it gets in. Whatever the system, the day-to-day job is the same: keep the pH of the solution in the slightly acidic range most crops like (roughly 5.5 to 6.5), keep the nutrient strength (EC) right for the crop and growth stage, and keep oxygen in the root zone. Aquaponics adds fish to the loop, with fish waste feeding the plants. For a shopping list, see our guide to hydroponic farm equipment.

Vertical farming vs greenhouse

The biggest difference is where the light comes from. A greenhouse gets most of its light from the sun at no cost. A vertical farm buys all of it as electricity, and lighting plus the cooling needed to remove the heat from the lights makes up most of the power bill. That’s why the energy used per kilo is the number that decides whether a vertical farm makes money.

What a vertical farm buys with that electricity is control and location. It can grow the same crop every week of the year, in a city, close to buyers, with very little water and no pesticide drift from neighbors. A greenhouse needs land and a good light climate, and it works harder in long, dark winters, but it costs less to build per square foot and runs far cheaper per kilo for most crops. Several well-funded vertical farms have closed in recent years, and our piece on the case against vertical farming looks at why.

Best crops for vertical farming and hydroponics

The crops that work in a vertical farm are small, fast and sold by quality rather than bulk. Lettuce and other salad greens, basil and other herbs, microgreens and baby leaf are the standard choices: they’re short enough to stack, they turn over in weeks, and nearly the whole plant is sold. Strawberries are grown in some vertical farms, but they need more light and pollination, which adds cost.

Greenhouses are where hydroponic tomatoes, cucumbers and sweet peppers do well. These vine crops grow tall, need a lot of light and run for months, which suits sunlight and drip-on-substrate systems. Staple crops such as wheat, rice or potatoes don’t make sense in either setting, because the value per square foot is far too low to cover the building. Our list of profitable greenhouse crops covers more options.

Starting or expanding a hydroponic farm

People who’ve done this tend to give the same advice: sell before you grow. A restaurant, grocer or wholesale buyer who will take a set volume every week matters more than the choice of system. After that, the order of work is usually this:

• Pick the site for power, water quality and distance to buyers, and get electricity quotes early.
• Choose a system that matches the crop, then size it in modules you can copy later.
• Budget for climate control, backup power and alarms, because a pump failure can lose a crop in hours.
• Plan food safety records, labor and a weekly planting schedule before the first seed goes in.
• Expand one module at a time once yields and sales are steady.

Building costs vary widely with climate and automation. Our breakdown of high-tech greenhouse costs for winter use and the guide to greenhouse automation systems are good next reads. If you run a crew across several houses or sites, our farm task management app assigns jobs, deadlines and instructions and shows what’s done and what’s late.