A greenhouse is a great way to extend the growing season, grow plants that wouldn’t survive outdoors in your climate, and protect your plants from pests and diseases. With so many options for greenhouse styles, sizes, and DIY kits available, it can be tricky to decide which greenhouse is right for you. In this comprehensive guide, we’ll share 25 greenhouse ideas to help you plan and build the perfect greenhouse for your needs.

Whether you’re a beginner gardener looking for a small hobby greenhouse or an experienced grower wanting a large commercial structure, there are many factors to consider. We’ll cover tips on choosing a greenhouse style and size, options for floors and foundations, ideas for benches and shelving, and ways to add ventilation, heating, lighting, and irrigation systems.

Read on for 25 helpful greenhouse ideas and inspiration to get your greenhouse planning and building project started!

Choosing a Greenhouse Style

When deciding on a greenhouse, the first decision is the style. The main options are freestanding, lean-to, window-mounted, and portable greenhouses. Consider the amount of space available, your budget, and how permanent you want the structure to be.

Freestanding Greenhouses

Freestanding greenhouses are fully enclosed structures detached from other buildings. They allow light through all sides and offer the most growing space.

• Pros: Freestanding greenhouses provide optimal light exposure, ventilation, and flexibility in size and shape. They can be sized to fit available space.
• Cons: More expensive to build than other styles. Require permanent foundation and are less portable.

Lean-To Greenhouses

Lean-to greenhouses are built against an existing building and use the building wall as one side. This style is easy to construct.

• Pros: Less expensive to build than freestanding greenhouses. Convenient access to utilities from attached building.
• Cons: Light only comes through 3 sides. Limited ventilation on building-side wall. Size and location restricted by existing structures.

Window-Mounted Greenhouses

Window-mounted greenhouses are small structures attached directly to the house above a window or door. This is the most affordable option for small spaces.

• Pros: Convenient access from indoors. Easy to install on suitable window. Maximum use of limited space.
• Cons: Size severely limited by window dimensions. Restricted ventilation and light exposure. Can lead to heat loss from home.

Portable Greenhouses

Portable greenhouses are lightweight structures that can be easily moved to different locations as needed. They come in many sizes.

• Pros: Flexible placement, easy to relocate. Quick to set up and take down. More affordable than permanent options.
• Cons: Not as sturdy and durable as permanent greenhouses. Limited ventilation and temperature control.

Choosing the Right Size Greenhouse

Determining the appropriate size for your greenhouse depends on what you intend to grow. Measure available space and consider room needed for plants, benches, walkways, and tools when deciding on size.

Small Greenhouses: 2 to 4 feet deep x 4 to 8 feet wide

Best for starting seeds, raising transplants, herbs, or a few small plants. Can fit on a patio or balcony.

Medium Greenhouses: 4 to 8 feet deep x 8 to 12 feet wide

Accommodate a wider variety of plants including vegetables, flowers, and small trees. Need more space.

Large Greenhouses: Over 8 feet deep x 12 feet wide

Support larger plants like mature tomatoes and small fruit trees. Allow room for shelving and work areas.

Commercial Greenhouses: Over 500 square feet

Sized for growing large amounts of plants for commercial sale. Require professional design and materials.

Aim for the largest greenhouse your space can accommodate, and remember to leave adequate room to move around inside. Extend the growing season by including heat and lighting systems.

Flooring Materials and Foundations

A proper floor and foundation are key to ensure the greenhouse structure is level and secure. Here are some flooring ideas:

Dirt Floor

A dirt floor is affordable and provides good drainage if soil quality is good. Dig down, level, tamp, and cover with gravel to prevent weeds and mud.

Gravel Floor

Gravel over soil, landscape fabric, or a vapor barrier is an inexpensive option. Use pea gravel or crushed stones 1/4 to 3/4 inch size for good drainage.

Concrete Slab

Concrete makes a permanent, durable floor. Install rebar, pour 4 to 6 inches thick, and level slab for positive drainage. Sealing the concrete helps moisture resistance.

Pavers or Bricks

Interlocking pavers or bricks make an attractive floor that allows drainage between cracks. Lay over gravel and sand. Best for level sites with good drainage.

Wood Decking

Wood decking makes a raised floor to prevent ground moisture. Use rot-resistant lumber and create spaces between boards to allow water to drain.

For freestanding greenhouses, concrete footings around the perimeter help secure the frame. Consider frost line depth when digging footer holes.

Ideas for Benches and Shelving

Once you have the greenhouse structure built, you’ll want to add benches and shelving to effectively use the growing space.

Benches

Benches maximize floor space for plants. They keep plants up off cold, wet ground and make them easier to tend.

• Use moisture-resistant lumber, metal framing, or plastic lumber to build benches. Allow 18-24 inch aisles between benches.
• Multilevel or tiered benches double planting space. Build 2-3 levels of benches on sturdy legs or shelves.
• Line benches with rigid plastic trays or polyethylene sheeting to contain soil and water drainage.

Shelving

Install shelving around the interior perimeter to utilize wall space. Consider height requirements for plants.

• Window shelves under greenhouse glazing allow light for starting seedlings and small plants.
• Wall-mounted shelves can hold tools and pots. Leave space under for larger plants.
• Vertical shelving, hanging buckets, and wall trellises maximize space for climbing vines and vining crops.

Make sure any lumber, metal, or plastic used inside the greenhouse is moisture-resistant and non-toxic to prevent contamination.

Ventilation Systems and Windows

Ventilation is critical in a greenhouse to control temperature, humidity, and air flow. Vent windows allow hot air to escape and fresh air to circulate.

Roof Vents

Roof vents near the ridge line allow rising warm air to escape while drawing cooler air in from lower side vents. Manual and automated vents are available.

Side Windows

Operable windows placed low on side walls bring in fresh air near plant level. Open windows on opposite walls creates cross ventilation.

Fans

Exhaust fans mounted high on end walls pull hot air up and out, creating air movement. Oscillating pedestal fans improve circulation.

Evaporative Cooling

Evaporative cooling systems such as wall or bench-mounted misters lower temperatures through water evaporation. Best for dry climates.

For maximum ventilation, aim for vents with opening size equal to 15-25% of the floor area. Open vents early to prevent overheating.

Heating Solutions for Greenhouses

Adding supplemental heat extends the growing ability of a greenhouse for year-round plant cultivation. Heaters warm the air and soil during colder months.

Electric Greenhouse Heaters

Electric heaters provide instant heat with adjustable thermostats. Choose unit size to adequately heat the entire space. Locate safely away from plants and damp areas.

Gas Greenhouse Heaters

Gas heaters burn LP gas or natural gas to produce heating output. Gas heaters need proper ventilation and installation by qualified professionals for safety.

Pellet Stoves

Pellet stoves provide steady, low-intensity heat from compressed wood pellet fuel. Automatically feed pellets from a storage hopper.

Water Heaters

Hot water piping systems use a water heater or boiler and pump warmed water through pipes or fins to heat the greenhouse.

Passive Solar Heat

Passive solar takes advantage of sunlight to naturally heat the greenhouse. Use solar heat absorbing materials and thermal mass. Close at night to retain warmth.

Proper insulation and an energy curtain can reduce heat loss and make greenhouse heating more efficient. Maintain adequate airflow and vent exhaust heat to avoid overheating.

Lighting Options for Greenhouses

Supplemental lighting is beneficial for starting seeds earlier, extending day length for growth, or illuminating shady areas. Different lighting options for greenhouses include:

Grow Lights

Full spectrum LED or high intensity discharge (HID) grow lights provide intense light plants need for growth. Use grow light stands with adjustable hangers.

High Output Fluorescent Lights

Fluorescent lights are affordable and emit moderate light levels. Use overhead fixtures or position close to plants.

High Intensity Bulbs

Metal halide or high pressure sodium bulbs give bright illumination from standard light sockets. Use durable protective covers.

Compact Fluorescents

Compact fluorescent bulbs screw into fixtures to provide brightness suitable for seedlings and transplants.

Natural Lighting

Maximize passive solar light through glazing material selection and placement. White paint increases reflection and diffusion.

Install lighting properly to avoid overheating, fire hazards, and excessive energy use. Place lights close to plants to maximize light intensity.

Greenhouse Irrigation Systems

Automated irrigation systems make greenhouse watering easy and efficient. Drip irrigation, misters, and hose-end timers prevent drought damage when you can’t hand water.

Drip Irrigation

Drip lines or tape with emitters directly soak the root zone less. Use valve timers and adjust for each zone.

Misters

Misting equipment increases humidity while lowering temperatures. Set automated timers early to prevent disease.

Hose-End Timers

Attach hose-end timers to outdoor faucets or indoor plumbing to automatically turn water on and off at preset times.

Self-Watering Systems

Self-contained water reservoirs with wicks or capillary mats passively move water to plants as needed, less labor.

Watering Cans

Good old-fashioned watering cans provide manual control for selective or spot watering. Use for small greenhouses.

Monitor soil moisture and adjust irrigation frequency and amount based on weather and planting conditions for optimal growth.

Accessories and Extras for Greenhouses

From automated controls to shading solutions, accessorizing your greenhouse helps maximize its functionality. Consider these additions:

Automated Controls

Automated systems monitor conditions and operate vents, fans, heaters, irrigation, curtains and more to create optimal growing environments.

Insulating Curtains

Energy curtains made of thermal fabrics can be closed at night to reduce heat loss. Retract automatically or manually.

Shade Screens

Interior shade cloth blocks excessive light and reduces temperatures. Manually install or mount on automated rollers.

Tool Storage

Use wall-mounted racks, shelving units, and pegboards to organize hand tools, gloves, watering cans and garden supplies for convenience.

Work Surfaces

Dedicate a potting bench, utility sink, or sturdy work table for repotting, taking cuttings, and propagating.

Greenhouse Staging

A rolling cart with shelves and trays lets you easily move plants around the greenhouse and transport to outdoor beds.

Budget-Friendly Greenhouse Ideas

Building a greenhouse doesn’t have to break the bank. Here are some budget-saving options:

DIY Greenhouse Kits

Prefabricated hobby greenhouse kits come with framing, panels, and instructions for DIY installation at a fraction of the cost to build.

Salvaged Materials

Check architectural salvage firms, classified ads or local swap boards for discounted or free windows, doors and lumber to use in your custom greenhouse build.

Polycarbonate Panels

Multiwall polycarbonate sheets cost less than glass and provide better insulation. Diffuses light without glare. Easy to install.

PVC Frames

Use PVC piping cut to size and joined with fittings to make an inexpensive custom greenhouse frame. Cover with plastic sheeting.

Secondhand Heaters

Repurposed unit heaters or appliances like old water heaters can provide heat on a budget with some wiring modifications. Use caution.

Prioritize good glazing, vents, and insulation when allocating budget. Save on decorative extras until later or build yourself over time.

Unique Ideas for Small Space Greenhouses

Lack of yard space doesn’t mean you can’t have a greenhouse. Use these creative small greenhouse ideas:

Indoor Greenhouses

Convert a sunny attached porch, garage, or spare room into an indoor growing area. Use grow lights to supplement natural light.

Outdoor Growing Chambers

An old fridge or freezer makes a quirky but functional insulated backyard greenhouse. Remove compressor and line with shelves.

Glazed Window Boxes

Mount a glass or plexiglass front onto a wooden planting box attached to sunny windows or railings. Protect from cold.

Sunrooms/Solariums

Enclosing an existing deck, porch or patio with polycarbonate roofing and panels quickly adds a temperature-controlled sunroom space.

Geodesic Domes

Geodesic dome greenhouses assemble from kits into free-standing spherical structures optimized for strength and light exposure with minimal materials.

Best Plants for Greenhouses

A greenhouse expands possibilities to grow tropical plants, flowers, vegetables, and fruits even in cold climates. Some top greenhouse plants include:

Orchids

Beautiful, delicate orchids thrive in warm, humid greenhouse environments. Provide excellent air circulation to prevent disease.

Citrus Trees

Grow lemons, limes, oranges, and other citrus in pots in the greenhouse. Move outside in warm months.

Succulents

Heat-loving succulents prefer the warm, dry conditions of a greenhouse. Plant in shallow pots with sandy, well-draining soil mix.

Pepper Plants

Get a head start on hot peppers and grow super-hots like habanero and ghost peppers in the greenhouse for bigger yields.

Tomato Plants

Start your tomato transplants early and grow long-season varieties to completion in the protected greenhouse space.

Tropical Fruits

Exotic tropical fruits like pineapple, banana, mango, and passionfruit can be grown as container plants in greenhouses.

Greenhouse Gardening Tips For Beginners

If you’re new to greenhouse gardening, follow these tips:

• Start small to keep initial costs down and get experience with greenhouse growing.
• Automate ventilation and use shade screens to prevent overheating on hot days.
• Improve soil drainage by mixing in sand, perlite, or vermiculite. Avoid topsoil and compost blends.
• Use drip irrigation systems and bottom-watering to keep humidity down and prevent foliar diseases.
• Scout daily for pests like aphids and whitefly which spread quickly in the enclosed space.
• Open doors and vents to allow air circulation and humidity control, even in winter.
• Keep accurate records of seeding dates, plant care, crop yields, and problems to improve over time.

FAQ About Greenhouse Gardening

How cold can it get in a greenhouse at night?

In unheated greenhouses, nighttime low temperatures are typically 10-20°F warmer than outside ambient air thanks to trapped thermal mass, but it can get as cold as the outdoor temperature. Additional heating is needed to maintain warmer night temperatures for plant growth.

What is the best glazing material for a greenhouse?

Glass glazing provides maximum light transmission but can be expensive. Polyethylene or polycarbonate panels are affordable greenhouse covering alternatives. Polycarbonate is more durable and insulating than polyethylene plastic.

Is a greenhouse worth the cost?

A greenhouse extends the growing season so you can grow more plants year-round, which can provide savings on grocery costs. For hobby gardeners, kits offer an economical way to build a small greenhouse. Larger permanent greenhouses are major investments but can increase yields commercially.

Where is the best place to install a greenhouse?

Choose a sunny, level site conveniently located near a water source and electricity if possible. South-facing locations provide the most light exposure in northern hemisphere. Prevent shade from buildings and trees which reduces sunlight.

What maintenance does a greenhouse require?

Expect to spend time regulating temperature, watering, providing adequate ventilation, controlling pests, and cleaning regularly. Automated controls reduce but don’t eliminate maintenance needs. Develop a schedule for cleaning glazing, removing plant debris, and disinfecting.

Conclusion

Building your own greenhouse creates a controlled environment to get a jump on the growing season and expand what you can grow. Large or small, simple or high-tech, a greenhouse opens new possibilities for the passionate gardener. We hope these 25 greenhouse ideas spark your own imagination and creativity as you plan the perfect oasis for your plants.

With smart design choices and proper care, a greenhouse can produce beautiful flowers, healthy vegetables, and bountiful food crops through the colder months. The satisfaction of nurturing your own plants from seed to harvest makes a greenhouse a worthwhile investment for any gardener.