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How Does A Greenhouse Work?

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A greenhouse is also called a forcing structure, that is, an artificial environment in which plants are “forced” to grow, despite the harsh outside climate. So, how does a greenhouse work? The minimum requirement for any greenhouse is that it allows warmth and light to enter, providing a microcosm climate favorable to plant growth.

Diagram of how a greenhouse works

But How Does a Greenhouse Work?

Every greenhouse operates on a simple physical principle called “the greenhouse effect”. Sunlight (short waves) passes through transparent or translucent materials such as glass or plastic. When it strikes an opaque surface inside (plant leaves, greenhouse floor, planters)  some of the light energy is changed into heat.

The darker the surface, the more heat is generated. The greenhouse panels are good at transmitting light, but not heat. Therefore, most of the heat stays inside.

Once the short waves hit the ground, they warm it up. Then the warmed air rises and heats up the greenhouse. Then long waves radiate to the atmosphere.

Books about greenhouses

Hydroponics and Greenhouse GardeningHydroponics and Greenhouse Gardening: 3-in-1 Gardening Book to Grow Vegetables, Herbs, and Fruit All-Year-Round Amazon buy buttonThe Winter Harvest HandbookThe Winter Harvest Handbook: Year Round Vegetable Production Using Deep-Organic Techniques and Unheated GreenhousesAmazon buy buttonGreenhouse Gardening: How to Build a Greenhouse and Grow Vegetables, Herbs and FruitGreenhouse Gardening: How to Build a Greenhouse and Grow Vegetables, Herbs, and Fruit All-Year-Round Amazon buy button

Optimal Growing Conditions

There are certain conditions under which plant growth, or photosynthesis, stops:

  • Temperature falls outside certain limits (for vegetables, usually 40° minimum & 90° maximum)
  • The intensity and duration of light does not meet certain standards (most vegetables require 4-6 hours of direct sunlight minimum, fruiting plants may need up to 8)

A greenhouse allows you to maintain the proper temperature and light conditions for optimal plant growth. For any greenhouse, the sun should be the primary heat and light source.

If we all lived at the equator, the sun would provide all our energy needs. But in many areas, particularly cold or rainy climates, supplemental heating and/or lighting may be necessary to sustain greenhouse growth.

Reminder: Don’t forget the “enjoyment factor” this stress-free personal retreat will provide.

Active plant growth produces more heat and also helps humidity to build up. Greenhouse vents and sometimes fans are necessary to exchange gases, cool and circulate the air, and drop the humidity level. Water and fertilizer provide plants with the energy they need to grow.

Your goal for your greenhouse is to keep the temperature, light, humidity, and nutrition parameters within the ranges preferred by the plants you want to grow.

Interested in Passive Solar Greenhouse methods?

Why should you get a greenhouse?

If you have even a small sunny spot in your yard, I believe your ultimate goal should be a greenhouse. Greenhouses provide more gardening space, total climate control, and the best (and free) light source of all…the sun.

When do you need a greenhouse? When your plants and enthusiasm have overflowed your house. Or you’ve become serious about supplying much of your family’s veggie needs yourself.

Look at the expense of a greenhouse as an investment in your family’s health and well-being. Providing significant amounts of high quality, nutritious, safe food is more than just a hobby… it may even mean survival!

What can you do in the greenhouse?

Here are just a few things you can use the greenhouse for:

  • store plants/seeds/bulbs for next year
  • propagate and experiment with plants
  • grow lettuce and other cold season vegetables

What should you add to your greenhouse?

In order to make your greenhouse more comfortable, you might want to add:

  • a potting bench
  • some shelving
  • maybe a sink

Our favorite greenhouse? It’s Solexx

A couple of men hanging onto a Solexx greenhouse frame

Are you interested in a greenhouse, but bewildered by the vast array of kits available?

We’re absolutely sold on a material for greenhouse panels called Solexx. The insulated glazing panels provide bright, even lighting which accelerates plant growth. Solexx kits include a fiberglass reinforced framework which is deceptively strong, UV resistant, and very easy to assemble.

Read all about Solexx greenhouses here.

How does a greenhouse work

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