How to Add a Greenhouse to Your Land

Has there ever been a gardener who didn’t wish for a greenhouse? Especially during cold months, passionate growers often want to spend more quality time in their flower and vegetable gardens. Protected growing offers just that.

There are many greenhouse types to consider, including a portable plant house, a mini growhouse, and a large hobby greenhouse. Whatever your gardening, space, and climate needs, there’s likely an option for you.

Choosing a greenhouse depends on the plants you want to grow, your budget, and how much time and energy you want to invest in growing under cover.

Planning is key, and you’ll need to make important decisions along the way. You can get started by answering these eight questions.

1. What plants do I want to grow

Some gardeners want a greenhouse to propagate plants for the outside garden or to extend the vegetable-growing season. Others have an interest in growing tropical flowers or vegetables all year long. More than a few want to grow in-demand crops to take to market.

The best greenhouse is the one that meets your plant needs. A small, unheated greenhouse that leverages heat only from the sun may be perfect to get seeds and plants started early in the season and to extend the season for hardy plants and vegetables. If you’d like to spend more time in your greenhouse for year-round growing, a larger heated space will give you many more options for planting tender vegetables, ornamentals, and houseplants.

2. Do I want to make or buy my greenhouse

There are several ways to add a greenhouse to your land at varying costs. You can:

• Buy a prefabricated greenhouse
• Purchase a kit and assemble it yourself
• Build a greenhouse from scratch with new or recycled materials

If you choose to build a permanent greenhouse structure from scratch, consider the following materials for your budget:

• A foundation, like concrete or timber
• Framing materials, like wood, steel, aluminum, or PVC pipe
• Translucent skin or glazing, such as double-walled polycarbonate panels, polyethylene sheets, or double-pane glass (keep in mind how well the glazing will hold up if you live in an area with high winds and heavy snow)

The Hobby Greenhouses guide from the University of Georgia Extension includes a chart with the pros and cons of each type of greenhouse glazing material.

3. Where will I place my greenhouse

Freestanding greenhouses should be situated so they run east to west, with the long sides facing north and south. Take your time to find a location that gets the most sunlight over the seasons in your region, especially during winter, when there are fewer hours of sunlight.

It’s also a good idea to locate your greenhouse where it will be convenient to walk or drive to, is accessible to water and utilities, has good drainage, and is out of the path of surface runoff water.

4. How large of a greenhouse do I need

Only you and your budget can decide the size of your greenhouse. However, “The Complete Guide to Greenhouses & Garden Projects” by Philip Schmidt recommends building or buying a greenhouse that’s at least one size larger than you think you’ll need. It’s cheaper to construct a slightly bigger greenhouse at the outset than to run out of growing space too quickly and have to add more.

As you decide your greenhouse size, make sure it has:

• Plenty of room to stand up and walk around in
• Enough door width for a wheelbarrow
• Space for planting in soil and/or benches (In his book, Philip Schmidt recommends if you want benches on both sides, choose a greenhouse that’s at least 8 feet wide by 10 feet long.)
• Room for shelves
• Storage space for tools, trays, flats, containers, hoses, and soil
• Room for a sink
• Space for hanging rods and other gardening essentials

5. How will I heat and ventilate the greenhouse

A greenhouse heated exclusively by the sun, which can be a freestanding structure or attached to a house (or other building), is usually used only for growing before, during, and after the peak gardening season.

A heated greenhouse, which can also be freestanding or attached to a building, allows for year-round growing. It also means an added expense. Heat sources can include electric, propane, natural gas, wood, fuel oil, or something else. Heating needs to be strong enough to keep the greenhouse at an ideal temperature. For most greenhouse plants, night temperatures of 55 to 65 degrees are adequate.

With heat from any source, the greenhouse needs ventilation. Even during cold winter days, hot temperatures in the greenhouse can burn plants. Forced air fans and roof and gable vents, –operated manually or automatically—can help control temperature and humidity.

6. How will I water my plants

Of course, water is a key ingredient in any growing operation, whether pumped from a well, provided by a city utility, or rainwater stored in a cistern. Experts at the University of Georgia Extension recommend having hot and cold water outlets. You should also have a plan for watering by hand or using automated watering controls for pumps, drip irrigation, and misting systems. Hydroponics and aquaponics are other options.

7. Do I need lights in my greenhouse

Supplemental grow lights aren’t a requirement for a greenhouse when there’s plenty of natural light during the day. However, lights will increase your growing capacity in winter when there’s less sunlight, especially in northern parts of the country.

The cost of lighting depends on what type of plants you’re growing and their light requirements. Common lighting options include compact fluorescent lights and energy efficient LEDs.

8. What about the greenhouse interior design

The layout of the greenhouse interior should be a prime consideration for maximizing the amount of growing space. You’ll want to map out:

• Potting bench placement
• Paths
• An aisle that’s about 3 feet wide
• Benches at a comfortable height (around 36 inches) and width (40 inches maximum)
• Raised beds
• Shelving
• Tiered or suspended growing systems

With the answers to all of these questions, you’re well on your way to enjoying a lush, bountiful greenhouse on your land.

Plants to grow in your greenhouse this winter

One of the joys of having a greenhouse is being able to grow plants during winter. For healthy growing, consider plants that share similar needs for space, light, humidity, and a range of optimum temperatures during the day and night.

Here are suggestions for winter greenhouse growing, from plants that can tolerate less than ideal conditions to those needing supplemental light and heat. During this season and future ones, experiment with different plants and keep a journal to track your favorites.

Plants to grow in a cool greenhouse

In greenhouses where temperatures range from 50 to 54 degrees during the day and 43 to 47 degrees at night, consider these hardy and semi-hardy plants:

• Vegetables: Microgreens, spinach, lettuce, peas, radishes, kale, arugula, mustard greens, beets, and carrots
• Flowers: Amaryllis, azaleas, pansies, chrysanthemums, and Christmas cacti

Plants to grow in a warm greenhouse

In greenhouses where temperatures range from 70 to 76 degrees during the day and 64 to 66 degrees at night, consider these tender plants:

• Vegetables: Tomatoes, cucumbers, peppers, and eggplants (growing fruits means supplemental lighting, using trellising, and perhaps pollinating)

Specialty plants: African violets, orchids, cacti, citrus trees, succulents, and spring flowering bulbs