How Much Does Building A Greenhouse Cost?

Greenhouse is a nice addition to any garden. It lets you grow crops all year round in a controlled environment. There are many factors to consider before getting a greenhouse, for example, would you like to build or buy a greenhouse?

If building sounds too hard for you, then getting a commercially available greenhouse is a good option. I can recommend a 6′ x 8′ Palram Nature Series Hybrid hobby greenhouse for a beginner and an established greenhouse gardener.

Follow these 14 steps to decide which greenhouse is the best for you and have a look at the Palram Hobby Greenhouse review. However, if you are a DIY guru, then you might be wondering how much does building a greenhouse cost.

In this article we break down the costs of building a greenhouse and what you need to consider in order to cut down on the building costs.

Things to consider before building a greenhouse:

1) Preparation of the site. The first thing which adds costs to building a greenhouse is the preparation of the site. If you are planning to build a greenhouse on a completely new site which has never been used, it should be leveled and excavated.

Also, the site’s preparation costs are affected by the choice of the greenhouse foundation. For example, if you want to raise a greenhouse above the ground, then you need to build a framework and, as a result, the ground should be excavated.

2) Foundation and Flooring. The cheapest option is to set up greenhouse directly on the soil. In this case you just need to invest into site preparation, make sure to level and compact the soil. It is a cheap and easy building solution if you are planning to grow directly from the soil. It offers good drainage and you can secure the greenhouse structure with ground stakes.

What to use for greenhouse floor?

Apart from soil, greenhouse’s floor can be solid made from concrete or brick and stone floor as well as mulch greenhouse floor. A slightly slope concrete floor not only provides the surface to walk on and prevent weeds and pests but also drains water away from the structure.

Brick and stone floors are good for drainage and increase humidity inside the greenhouse. Mulch floor is a cheap option which prevent weeds from growing.

As mentioned above, if you want to raise a greenhouse above the ground, you need to build a foundation. A cheap and easy option would be to build a perimeter base. You can use the materials that you already have like treated lumber, breeze blocks, kerb-style slabs, bricks, paving slabs or concrete.

Sturdier foundation options require more expensive materials like paving slabs or concrete. Although paving slabs provide natural drainage in greenhouse, with concrete foundation you need to have a drainage system in place.

3) Do you need a Drainage System? Building a drainage system will add up to the overall costs but in some cases it is much needed. However, if you set up a greenhouse directly on the soil, the cheapest option would be to cover the half of the floor with gravel to drain the water away.

If you are going to build a concrete foundation, then you need to install a French drain. Just use a step-by-step instructions on how to build a French drain for a greenhouse.

4) Attached or Freestanding greenhouse?

Building an attached greenhouse (connected to the house) is very cost-effective as you can save on building materials. Another advantage of building attached greenhouse is that you don’t need to think about connecting electricity and water. However, some of the drawbacks include lack of sunlight, problems with maintaining the optimal temperature.

Also, an attached greenhouse can be limiting in space if you are planning to plant a lot of different plants unless you build an even-span attached greenhouse. I would personally recommend building a freestanding greenhouse structure.

5) Think about the type of greenhouse structure you want to build. The most expensive and time-consuming greenhouse structure to build is post-and-rafter as it has a rafter which provides extra support to the roof.

Many greenhouse gardeners prefer to build a traditional Even-Span greenhouse as it utilizes the most sunlight and provides a lot of growing space.

6) Decide on the size of the greenhouse. A size of greenhouse you are going to build directly affects the costs. Building costs for a small 6′ x 8′ Even-Span greenhouse vary from 100 to 200$ depending on the materials used.

What materials do I need to build a greenhouse?

What greenhouse materials you need to build a greenhouse depends on the structure of the greenhouse, what frame and glazing you want to choose as well as floor and foundation.

Generally, to build a greenhouse you can use wood, aluminum, galvanized steel or PVC plastic materials for the frame and glass, polycarbonate, plastic film, fiberglass or acrylic for glazing panels. Also, to build greenhouse floor and foundation you can use concrete, bricks, paving slabs, stone or lumber.

7) What greenhouse frame to build? Back in the days the most common material for a greenhouse frame was wood. Nowadays gardeners opt for a galvanized steel or aluminum frame. It is easier to set up and you can grab it for cheap.

For example, 7 feet long aluminum frame costs around 4.20$ whereas a linear foot of wood is a dollar and linear foot of galvanized steel costs 2.50$. To find more information on what frame material to use for a greenhouse click here.

8) Make up your mind what glazing to use for greenhouse. A traditional option is to build a glass greenhouse but it tends to be quite expensive. I would recommend going for 4mm polycarbonate greenhouse cover. It is around 140$ for five 48″ H x 24″W sheets which you can trim with scissors to fit the 6′ x 8′ greenhouse and you will have some left for replacement.

Also, depending on the frame material, consider other glazing options like polyethylene film. It works well together with the PVC frame.

9) How you are going to vent a greenhouse?

When building a greenhouse you need to consider what type of ventilation you will have in place. The cheapest and in some cases sufficient type would be to ensure that there is natural ventilation.

So you need to install roof vents on both sides of the structure and a couple of louvered vents at the bottom. You can find a louver vent for 10 dollars and you can also get automatic vent openers for roof vents which are in a range of 20 to 40$.

However, if you are building a large greenhouse, relying on natural ventilation might not be enough. You will need to have a fan ventilation, I would recommend setting up an automatic exhaust fan (70$) in the end of the greenhouse roof.

Also, you need to install an automatic intake shutter (36$) on each side at the bottom to intake the fresh air.

10) Do you need to heat a greenhouse?

Unheated or cold greenhouse is enough to grow tomatoes and cucumbers in summer, Chrysanthemums in fall and alpines, bulbs and cacti in winter. Unheated greenhouse shelters plants from wind, rain, snow and frost but the temperature is around 28°F (-2°C) which is not suitable to overwinter frost-sensitive plants.

If you want to grow vegetables all year round, then you need to invest into a greenhouse heater. However, depending on the weather in your area, it might be sufficient to heat a greenhouse naturally with no electricity.

If heating is required, paraffin heater is cheap to buy (100$) and cheap to run as gallon of kerosene costs around 3.58$ (New York Statewide Region) and it will last for 25 hours. Alternative, you can get another type of heating system according to your needs.

11) Watering system. When planning to build a greenhouse take a moment to think how you are going to water your plants. How much water you use depends on the plants that you grow. Rather than filling up a watering can with tap water, I suggest setting up a guttering system.

Also, a very economical decision is to collect the rainwater from greenhouse structure into water barrels and connect the watering system. For example, you can buy a drip irrigation kit for around 30$ which connects to the rainwater barrel.

However, some of you might question why to use rainwater where you can fill up the watering can with tap water. Have you noticed white deposits after prolonged watering with tap water? This is calcium which and excess of it on soil can impact the uptake of other vital nutrients by plants causing nutrient deficiencies.

There are many reasons why rainwater is much better than tap water for plants and you can consider collecting rainwater before building a greenhouse.

12) Do you need greenhouse shelves and benches?

It is entirely up to you if you would like to build or buy greenhouse shelves and benches. Although it is handy to keep planting tools and supplies on them, but an average cost of the galvanized steel workbench is around 70-75$. For someone who is going to use it for potting it can be a good investment, you can also use benches as extra space to keep potted plants.

Greenhouse shelving helps to organize space within the structure more efficiently. The more expensive option (157$) is to buy a bundle of 4 aluminum shelves with heavy duty steel brackets that can hold up to 90 lbs (40 kg). Alternatively, you can get a 4-tier greenhouse shelf unit for 70$ to keep the potted plants and your tools.

So, how much does it cost to build a greenhouse?

If you want to build a greenhouse on your own, the average cost of building a greenhouse can be around 665$ keeping in mind that the site is leveled.

Here is a breakdown of the building costs for a 6′ x 8′ freestanding Even-Span greenhouse construction according to the following building plan: