How to Grow Microgreens in a Greenhouse: The Complete Guide

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Growing your own vegetables and microgreens can be hugely beneficial for your health, the environment, and your bank account. Growing microgreens have become increasingly popular in the last few years as they have been used more widely in the kitchen, both for their taste and the health benefits they offer. You can grow them on a small scale inside your home or go bigger and invest in larger crops using a greenhouse.

Whether you are looking to grow a larger scale for your own consumption or planning to start a microgreens business, we’ll guide you on how you can go about it using a greenhouse.

How to grow microgreens in a greenhouse? Growing microgreens requires first building or buying a greenhouse and obtaining seeds for your microgreens. Then, choose the variety of microgreens you want, set up automated watering and create an optimal climate in your greenhouse for your greens.

If you are just beginning your journey of growing your own microgreens, you’re in the right place! In this article, we will cover greenhouse tips as well as how you should go about growing in your greenhouse step by step so that you are successful in growing your own food. Finally, we will talk about health benefits, when to harvest, and the profit margin of growing greens. 

Greenhouse Specifics

Before you buy or build a greenhouse there are a number of things you should consider. First, you will also want to research if you need a building permit to build a greenhouse in the area you are looking to set up. Depending on where you live, you may need to consult the city before building any new infrastructure. 

Next, the location of your greenhouse is going to be critical in the success of your plants. You are not going to want to put a greenhouse in a spot that is constantly shaded, because then if you plant greens that need sunlight to thrive. Remember, it’s easier to provide shade than create sun. You can buy shade cloths if you build your greenhouse in an area that is in full sun.

Before you decide on building or buying a greenhouse kit, you will want to double-check the measurements and be sure a wheelbarrow will fit through the door. Be sure your greenhouse is the size you want it to be, keeping in mind you will likely be able to fill it regardless of size because you will just continue planting. 

It is better to have too much space and have the potential to expand than to not have as much space as you want to have and need to break down a wall to expand the greenhouse. Building an edition is going to end up being more expensive than buying a larger greenhouse in the first place. 

Buying vs. Building Your Greenhouse 

Before being able to grow your own microgreens, you will need to decide if you want to build a greenhouse or buy a greenhouse. There are benefits to both; however, the deciding factor for many of us is often the cost difference. 

Although pricing can often be very similar, it is ultimately dependent on the type and size of greenhouse you are looking to have. If you are buying a kit and are not making any modifications to it, it is likely going to be cheaper than buying the materials individually and building from scratch. 

This is primarily because when you buy a kit you have every resource you need rather than having to buy every nail and piece of glass individually. This is challenged when you buy a kit but make many changes to it—this will add cost on top of the original price of your kit. Keep in mind that shelving and benches also usually are going to be sold separately. 

However, if you are planning on sticking with a plan offered by a kit, you are likely to get the most for your money by buying instead of building. Consider if you are going to need a foundation for your greenhouse. Whether it is a path from your gardening bench to the greenhouse or a foundation within the greenhouse.

You do not need a full concrete floor within your greenhouse, however, if you do have some kind of path it will make it easier for you to bring your wheelbarrow up for planting. Remember if you do put concrete down, you will need to include a drain in your flooring to avoid pooling water. Concrete can also get slippery when wet if you do not choose concrete with texturing.

If you use pavers as the flooring you are likely to get weeds between the cracks, however, these will allow for drainage after watering. Another flooring option is pea gravel; this will help you to avoid the ground getting muddy and damp. 

Heating your Greenhouse

Finally, remember that you will need to have a heating aspect in your greenhouse for maximized growth. The heat is what separates growing in a greenhouse from trying to grow in the dead of winter. For your heating, you can utilize electric, gas, propane or natural gas heating. 

The differences in kinds of heating are going to really be seen in how it has to be set up. You will need to decide if you want to have lines laid down for heating and if you have proper venting for your electricity. Another factor is what is going to be the easiest and most available in your area. If you live somewhere with a lot of outages, using electric heating may be the death of your plants. 

The cost of heating your greenhouse is going to be very dependent on the size of your greenhouse and the material you have used for your siding. With your siding you want as much light to enter as possible while also being heat-efficient. Generally, your choices will be glass or a plastic such as a fiberglass, polycarbonate, or polyethylene film. 

Each one of these options will offer you different glazing and different levels of heat trapped in the greenhouse. Nowadays, the majority of greenhouse kits are going to have siding materials that are efficient since so much research has been put into the optimal materials to use for siding. 

Therefore, one of the most distinguishable ways these materials differ from each other is in the cost of using them for your siding. On top of that, some materials are going to hold up better than others. 

For example, polycarbonate is one of the top recommended materials to use for siding. This is mostly because it is almost as transparent as glass and is the strongest material you can use for your siding. In addition to its strength, it will last you up to two to three times longer than any of the alternatives. 

Polycarbonate comes in single, double, and triple wall thickness which makes it easy to customize based on your needs. However, changing the thickness of your siding material is one of the ways you can make alterations to your greenhouse kit, which will increase the overall price you are spending on your infrastructure.

With all the materials mentioned above, you cannot go wrong, all of them will successfully trap in heat and work well for your greenhouse. To decide the best material for you, we recommend looking at your climate, budget, and the way you want your greenhouse to look. These factors will likely help you narrow down to one material to use for siding. 

Glass Siding

Using glass siding is going to be the most attractive looking of all the siding materials you could use but will be the most inefficient for heating and the most breakable material. You will need to invest in a double or triple strength glass to ensure your siding is not always breaking on you. 

Glass may result in an increase in plants burning because it doesn’t diffuse light. You will need to purchase a sturdier frame as glass is a very heavy material, especially in large sheets. If you are hoping to use glass you may need a professional to install it because it requires perfection in the framing. 

Fiberglass Siding

This material is not going to be transparent but will still let in as much light as glass, which can result in some plants burning. However, a benefit to fiberglass is that it can be coated in UV protection to cut back on plant damage. It will retain heat better than glass and with all our plastic materials, they will be significantly lighter than glass to make for easier installment. 

Fiberglass will provide good insulation as is a good starter material for those who are simply looking to begin growing their crops a bit earlier every year. This may not be the optimal material for a farmer looking to plant year-round and produce a high quantity and quality of plants. 

Keep in mind the UV protection will burn off after six years, so if you do get this material you will need to replace or recoat the UV gel every once in a while. Additionally, it is a bit harder to clean and if the windows get too dirty less light will be able to come into the greenhouse. 

Polycarbonate Siding

Polycarbonate is almost as transparent as glass and is the strongest of all the materials you can use for siding. As previously mentioned, you can buy polycarbonate in a single, double, or triple wall thickness. The single will be the least expensive and make the sleekest appearance. However, it will offer the least heat retention, light diffusion, and strength.

For those reasons, we recommend getting a thicker polycarbonate. These have air pockets between the panes of plastic which provides optimal insulation. So while they are more expensive, you will save on heating costs which may end up saving you money in the long run as polycarbonate has a 15+ year lifespan. 

Polyethylene Film Siding

This option is going to be a quick and inexpensive option for those gardeners or farmers whose primary purpose of their greenhouse is for seed starting. The sheets of polyethylene can be doubled to provide you with better insulation if you need it. This material works well but will not last you as long as the alternatives, as it can last about two to four years. 

The lifespan of the siding will be hugely dependent on the product and the weather/climate you live in. Many growers enjoy using this material because it is cheap and easy to replace every few years as needed. This offers you flexibility and easy installation. 

If you are trying to decide between using this material and a more costly one, consider how long you will want to operate your greenhouse and project the amount of money you will have to spend on polyethylene film in 15 years versus buying polycarbonate once in 15 years for example. This may help you make your decision between these differing materials. 

Now That you Have your Greenhouse, Let’s Start Growing

Microgreens have grown in popularity over the past few years both in restaurants and the rate at which people are choosing to grow them in their greenhouses. On top of that, they have a high-profit margin which is beneficial for farmers when they have a low harvest. 

The first step to growing your greens is buying seeds. There are a variety of distributors of seeds, such as Johnny’s Selected Seeds or True Leaf Market. They sell both mixtures of seeds and packets specifically curated for growing microgreens, this will be a bit easier than regular seeds however, these are also an option. 

You do not need to choose a specific brand of seeds by any means; however, you do want to focus on finding untreated seeds that are preferably organic. These are going to be the same seeds used to grow the full-size plants, just harvested at an earlier phase. 

The other difference is that you will need more seeds to grow microgreens due to how close together they need to be planted for optimal growth. Additionally, the cost of growing is going to differ depending on how many trays you are filling. In the following chart, you will see the outlined cost per tray of seeds.

Fixed Costs10” x 20” tray$1 per tray
Variable CostsSeeds< $15/lb ($1 per tray)
Soil~ $1 per tray
WaterDiffers by crop
PackagingVaries
Total$2-4 per tray

With your average cost being between $2 and $4 per tray, your costs are decently low for growing microgreens. The majority of your operating cost is going to be put into the initial cost of your greenhouse. Overall, growing your own microgreens is going to save you money over buying them in the grocery store.

When you’re choosing which microgreen you want to grow, start with the easiest ones to grow such as mustards. They are going to be one of the easier types to grow if you are just starting out. However, if you are confident in your green thumb or want a challenge, try cilantro, arugula, or another variation of microgreens. 

Location

Location within your greenhouse is important for ensuring your microgreens are healthy. They will not grow if they are cold. If you expose them to freezing temperatures they will die. However, they also need a bit of moisture in the air with decent ventilation. Therefore, if you are trying to grow microgreens in your home they may not be as successful as in a greenhouse. 

Depending on the time of year and how warm your greenhouse is, you may want to use heating pads to keep the soil warm. If you live in an area that does not drop below freezing, you are unlikely to need additional heat. Regardless, you will want to plant them in full sun to maximize their growth potential. 

Since microgreens are a bit particular about their environments, your greenhouse will make the growing process a lot easier. Often people will use humidity tents to speed up the germination process, this is fine but be sure to remove the tents once the greens sprout. If you keep humidity tents up, they are at greater risk of burning if/when your weather warms up.

Planting and Maintenance

When you are planting your seeds, you’re going to want to make sure your seed coverage is good as they need support while growing. If your seed coverage is ample, you will see your microgreens grow thick and healthy. Once the seeds are laid, press them down into your soil softly. Be sure they are wedged into the soil without being buried. 

The soil you use is not going to be hugely important in the growing process. You can use any high-quality potting soil, however, many growers have seen increased success using soils that are fortified with natural ingredients. A common ingredient that may aid in the growth of your microgreens is soil fortified with kelp.

If you accidentally bury your seeds you will have sprouts growing with soil on their leaves which may be challenging to wash off of the sprouts once you’re going to eat them. Keeping in mind the temperature and humidity the microgreens will want to grow in, the process of watering your greens is also critical for growth. 

When you first plant, you can lightly sprinkle some water over the top of the soil to give it a little bit of moisture. Top watering is ok until the seeds germinate, at which point it is important that you switch over to bottom watering. You can do this by putting the tray of soil that you planted in on top of a tray of water. 

Leave the tray to soak for about 20 minutes before checking how much the soil was able to absorb and pour the water out. If the soil has absorbed enough water, it should look and feel moist to the touch and also be evenly watered. Ensure there are no dry patches in the soil after watering.

By switching over to bottom watering, you are allowing the roots to soak up what they need and avoid overwatering or damage to the sprouts. If you overwater you also run the risk of causing diseases that can affect the plant due to overly wet conditions. 

Diseases such as gray mold and damping off are possible to form in microgreens from overwatering and are generally then exacerbated by a lack of air circulation. This highlights the importance of having a good watering system and proper ventilation in your greenhouse.

Selling your Microgreens

If your primary motivation is to grow microgreens to then package and sell to consumers, it’s important to know which are going to be the most profitable and try cutting back on growth costs. 

If you are consistently growing microgreens, you are likely to have batches ready for harvest approximately every two weeks. Therefore, a skilled grower who has space and time may be able to produce 20 to 25 crops per year in a normal greenhouse. However, your outputs can be more than doubled if you stack your trays vertically in your greenhouse. 

The more trays you grow, the more you will be able to make off of your microgreens. And with the input cost of trays being low, the profit margin is high. If you use a four-rack system you can produce an average of 50 pounds of your microgreens within a 60 square foot growing space, per two-week cycle of growth. 

If you sell at a farmer’s market or to people locally, you can bring income every two weeks for your microgreens. The majority of farmers can sell their microgreens for about $25 per pound. 

Therefore, if you are growing to profit, the best thing you can do is fit as many trays of microgreens into your greenhouse as possible because if you stick to one tray you will likely only produce about five to six ounces of microgreens per single tray when grown on one single level.

Harvesting Time

As previously mentioned, most of the time your crops will be ready for harvest in about two weeks after you’ve planted them. A good indicator is that the microgreens have produced a second set of leaves which as referred to as their “true leaves”. 

For some farmers, especially those aiming to make a profit, they will allow certain trays to grow for an additional week. This results in a product called baby greens which are also going to be a profitable and popular product to sell to consumers at farmers’ markets. 

Health Component

If you are growing to sell to consumers, this can be a very successful way to bring in a little bit more money as you can sell microgreens for about $25 per pound. These microgreens are extremely popular as they are known to contain up to 40 times more nutrients than mature plants. 

There are a variety of different kinds of microgreens, making them appealing to most people. Some of the most common types include:

Since there are so many microgreens you can grow, there is likely at least one variation that someone will be drawn to, both for taste and health benefit. Microgreens are high in vitamin C, vitamin E, vitamin K, lutein, and beta-carotene. 

RELATED: The 14 Most Nutritious Microgreens To Grow And Eat

These nutrients are beneficial for the health of our eyes, skin, and can protect the body against cancerous cells. This is one of the reasons microgreens have become increasingly popular and more and more people are working to implement them into their diets. 

Conclusion

If you are ready to try your luck with growing microgreens, you may be able to cut back on your grocery store cost and make a side profit on selling the excess microgreens you grow. If you’ve already started on your farming journey and have a greenhouse, you can jump straight to buying your seeds and growing your crops.

The most time consuming and costly part of your growing process is going to be buying a kit for a greenhouse or building your own greenhouse. If you are growing in your backyard or somewhere on your property, be sure you are thinking about the location and how much sun the spot you choose gets during all seasons of the year. 

If you are not in full sun throughout the year you may not be maximizing your growth. If you are buying a kit for a greenhouse, remember that certain things are going to be sold separately. Items you may want that will not come with a greenhouse kit include any watering systems, lights, flooring, benches, and shelves. 

Other factors to consider include providing a pathway to your greenhouse to ensure you can get your supplies into the greenhouse by your wheelbarrow. Before you decide between buying or building a greenhouse, be sure to make a budget and layout the cost of each option to ensure you can afford the size and type of greenhouse you are looking for. 

Once you start planting, be sure you are consistent with your watering and are keeping up with the climate inside your greenhouse to optimize your output of microgreens. If you have good insulation, ventilation, and sunshine, you are likely to produce a good amount of crops!

Microgreens Corner
Microgreens Corner
We are Janette & Jesper, and we love microgreens.

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