Greenhouse Buying Guide for Home Gardeners

Greenhouses control conditions so that you can grow plants in a protected environment. When you start seeds or propagate vegetative cuttings in a greenhouse, you can be assured that the plants are getting a strong start.

The fact is, you can be a successful gardener without ever using a greenhouse. However, once you have a greenhouse, your gardening experience changes so that you can stretch seasons and shelter plants from extreme weather conditions.

As lovely as they are, for most home gardening, you may not need a large greenhouse structure. You may be able to use a lean-to, or a pop-up greenhouse. Small mini-greenhouses can be used for indoor seed starting or to house tropical plants. Many gardeners place these in cool indoor spaces like garages and basements.

However, if you're a serious gardener looking to expand your gardening capabilities, a full-size hobby greenhouse may be just what you need.

In this guide, learn the features of home greenhouses and how to select the best greenhouse for your type of gardening.

There's a greenhouse to suit every kind of gardener. Check these out:

• Walk-in greenhouses are the structures that most often come to mind when we think of a greenhouse. Many come with features like doors to control access, and vents that control temperature and humidity.
• Mini greenhouses are smaller, compact options that are suitable for small spaces and smaller projects, like starting seeds.
• Hoop houses are tunnel-shaped walk-on greenhouses. They're often made with galvanized steel frames.
• Lean-to greenhouses are small structures that are built against a structure like a house or shed.

Experts recommend that if you're buying a greenhouse, to go ahead and size up to the next level to give your hobby room to grow.

The greenhouse frame material is an important consideration for a long-lasting and weather-resistant structure.

• Aluminum is lightweight, durable and resistant to rust. Powder-coated aluminum frames offer an extra layer of protection and are resistant to scratches, chipping and corrosion. Unlike unfinished aluminum frames, powder-coated aluminum frames do not require routine maintenance to look good.
• Galvanized steel offers strength and durability for permanent greenhouse structures. Galvanized steel is rust-resistant.
• Cedar and redwood are traditional aesthetic choices. Both woods are resistant to rot and insects, but, unlike metal frames, will require maintenance like sealing and painting.
• PVC and plastic are often used for portable, "pop-up" and temporary greenhouses. While they're not as durable as metal, they're lightweight and easy to assemble.

The transparent covering over the greenhouse frame is called glazing. Here are the most popular choices:

• Polycarbonate panels offer good insulation and light transmission. They are lightweight, durable and impact-resistant. Look for twin-wall or multi-wall sheets for improved insulation quality.
• Glass is a traditional choice, and offers high quality light transmission, but it's fragile and, once broken, will need to be replaced. Glass panels are heavier than polycarbonate and will require a stronger frame. If you prefer glass, look for tempered glass.
• Plastic sheeting or polyethylene film is the most economical choice. It's used in hoop houses and mini-greenhouses because it's lightweight and easy to install. Sheeting is less durable, offers less insulation and has a shorter lifespan than other materials.
• Note that polycarbonate is more energy-efficient, while glass provides more clarity of light.

Sometimes, the type of greenhouse you select determines the foundation. No matter the size you choose, consider how your greenhouse will attach to the ground. Here are some options:

• A concrete slab is typical for larger, permanent greenhouses. Slabs offer stability, durability and are easy to clean. Concrete slabs are expensive and labor-intensive to install.
• Options include paving slabs or bricks laid on a base of sand and gravel. These provide good drainage. They're an affordable choice for hobby greenhouses.
• Gravel is a good choice for basic and temporary greenhouses. Gravel prevents water from pooling, but does not offer stability or insulation. Gravel foundations may require additional anchoring to prevent shifting in high winds.

When you're ready to shop for a greenhouse, there are many factors to consider. First, think about the type of gardening you plan to do. Are you growing flowers or vegetables for outdoors, or do you want a space for your collection of tropical houseplants? Are you a cut flower gardener looking to produce seedlings at scale? Will a portable greenhouse or a lean-to greenhouse accomplish your goals instead of a full-size greenhouse?

Know your budget for this project. You can spend a relatively small amount on a temporary pop-up greenhouse that may suit your needs or you can drop a lot of funds on a top-of-the-line dream greenhouse. Set your budget amount and make decisions based on what you can afford.

Your budget will influence the size of your greenhouse. Sometimes, a portable greenhouse that you can prop next to a sunny wall is all that you need to get your seeds started and to protect tender tropical plants. Or, you may want a hobby greenhouse with room to produce trays of seedlings for your vegetable garden or flats of annual flowers for container gardens.

Site and location figure into the greenhouse selection equation. Whether your space is a cool basement, a sunny patio, a backyard or a hobby farm, there's a greenhouse option for you. If this is an outdoor greenhouse, you'll need a full site with at least six hours of direct sun each day.

Keep in mind that easy access to water is important for all sizes of greenhouses. Ideally, you'll have a faucet nearby to make watering plants a breeze. And ready access to electricity is necessary for larger greenhouses. If you need to run plumbing or electric to your greenhouse, be sure to factor those expenses in your budget.

Know the skills needed to build a greenhouse from a kit. Small mini-greenhouses can be quickly put together with common tools. Larger buildings require site prep and a team of helpers. Read product descriptions and reviews to prepare for the build.

Aesthetics are important, too. Homeowners, consider that a permanent greenhouse structure may impact your property's value. If you're in a homeowner's association, consult your HOA's rules that may apply to a greenhouse.

Tip: If you're in a municipality, check local zoning regulations on building a greenhouse on your property.

Greenhouses are designed to control temperatures and airflow. Certain features allow greenhouses to maintain consistent temperatures to benefit your plants. In colder regions, snow load is a factor when choosing a sturdy greenhouse that will perform in freezing weather. If you need to heat the greenhouse through winter, look for a greenhouse model that will accommodate the kind of heater you prefer.

In warm temperatures, greenhouses can overheat. Greenhouses have ventilation options like roof vents, side vents and louvered windows that let you control heat and moisture inside the structure. Top of the line greenhouses have automatic vent openers. Greenhouses also use built-in shading features like shade cloths to protect plants from intense sun.

For a walk-in greenhouse, having one or two easy-to-use doors is important for a comfortable working space. Additionally, some greenhouses come with integrated or customizable shelving that helps you optimize the growing space.

Greenhouse sizes:

• Mini greenhouses are usually 2- to 3-feet wide, ideal for patios and apartment balconies.
• Small walk-in greenhouses are typically 4-by-6 feet to 6-by-8 feet and are a good choice for hobby gardeners with big dreams and small spaces.
• Medium greenhouses are usually 8-by-10 feet or 8-by-12 feet and are popular for producing a variety of plants.
• Large greenhouses at 10-by-16 feet or larger bridge the gap between hobby gardeners and small commercial growers.

When you build out your greenhouse, consider these accessories to enhance your growing experience.

• Greenhouse shelves, tables and benches give you space to work and store your plants. A potting bench offers a worktop to pot plants, plus shelves for storage. Wire grid top tables are a practical choice. The design ensures efficient drainage and air circulation around plants.
• Greenhouses need air flow to prevent certain diseases. Automatic vent openers, fans and louvers regulate temperature and air circulation.
• A greenhouse heater for winter and shade cloth for summer will help regulate temperature in the structure.
• If you're adding a larger greenhouse, you'll need drip irrigation or misting systems for efficient watering. For smaller greenhouses, a garden hose and reel and a good quality watering wand are needed.
• If you're growing climbing plants, you'll need plant hangers and possibly a trellis.
• Greenhouse anchors are essential to secure your greenhouse in high winds.
• Tools like a thermometer and a hygrometer (used to measure the amount of humidity in the air) are necessary to keep your plants in a healthy environment.
• Grow lights are necessary in seed starting. Heat mats are useful, too, when starting seeds.
• If you have the room, a small raised garden bed is nice inside a greenhouse. It's a good place to start seedlings or to grow entire crops like lettuce in a protected space.

Most small and medium greenhouse kits can be assembled as DIY weekend projects. Gather tools like a power drill, wrench, screwdriver, tape measure, level and a step ladder to build the structure. Be sure to thoroughly read the manufacturer's instructions before you begin to build.

For larger greenhouses, consider hiring pro installers. They have the expertise to handle the materials and make sure your greenhouse is level, square and weather resistant.

Steps for building a greenhouse from a kit:

• Prepare the site before you build your greenhouse. You'll need a level foundation to support the greenhouse structure and prevent drainage issues down the road.
• Unpack and organize the parts according to the instruction manual.
• Assemble the base frame.
• Erect the wall frames. Use a level to ensure the frames are plumb.
• Install the roof frame.
• Carefully insert glazing panels into the frame channels and secure with the manufacturer's clips, gaskets or sealant.
• Assemble and install doors and vent windows and make sure they work properly.
• Check all connections and apply any weather stripping or sealant to prevent leaks.

For larger greenhouses, consider hiring pro installers. They have the expertise to handle the materials and make sure your greenhouse is level, square and weather resistant.

Pro tips for building a DIY greenhouse from a kit:

• Measure across the diagonals to make sure everything lines up before you tighten the bolts. This ensures the frame is completely square.
• Anchor the greenhouse to the base. This can be a concrete slab or other type of base, or deep ground anchors. Anchoring keeps the structure standing during high winds and protects your plants.

When you care for your greenhouse, you ensure that it will function well and protect your plants for years to come. Routine maintenance saves you money and provides a healthy growing space for your plants.

Tips for maintaining your greenhouse:

• Monitor the temperature and humidity with a thermometer and a hygrometer. When you have plants in the greenhouse, try to keep tabs on the temperature every day, and if possible, monitor temperatures throughout the day.
• Keep your greenhouse, no matter the size, in good condition by regularly washing the greenhouse panels and sweeping out plant debris. In addition to routine cleaning, deep clean once a year. Wipe down surfaces to prevent disease spread.
• Check the structure for damage in every season, especially after extreme weather events. Look for cracks in panels, tears in plastic film or loose weather seals. Taking time to fix leaks when they happen will keep your heating costs low.
• Warm, humid greenhouse air invites pests like aphids and whiteflies. Routinely scout plants by turning over leaves to look for these tiny bugs and promptly treat the pests when you find them. Pick up plant debris on surfaces and floors and keep hoses off the ground, as well.
• When equipment like roof vents and exhaust fans break or malfunction, repair as soon as you can. Good airflow is essential to growing plants in a greenhouse. Delaying repairs can damage your plants.

Your gardening hobby will benefit from any size greenhouse. If you're gardening on a budget, there are plenty of affordable options for growing plants in a greenhouse.

Begin by looking at budget-friendly kits like portable greenhouses and small tunnel structures that use lightweight plastic covers. These lightweight structures accomplish the goals of extending the growing season and starting seeds.

There are classic DIY greenhouse options like a hoop house using PVC pipes and polyethylene film, or upcycled glass windows to construct a custom stand-alone or lean-to structure. Check out our guide for building a lean-to greenhouse.

When it comes to greenhouse accessories, prioritize essentials like good airflow and temperature control. Keep in mind that manual roof vents work just as well as expensive automatic openers.

Outfit your greenhouse with secondhand items like shelves. You can make your own benches and tables from scrap wood. Look around your home for items you can repurpose into plant hangers and trellises.

Tip: Check local online marketplaces and community groups for items you can use in your greenhouse.

Where is the best place to put a greenhouse?

The perfect spot for a greenhouse should be level with good drainage to prevent standing water. You want a full sun location that gets at least six hours of direct winter sun, ideally facing south or southeast. Make sure the location is protected from strong winds by a structure like a house, fence or even a hedge. Finally, place your greenhouse close to water lines and electricity.

Do I need a permit for a greenhouse?

Check with your local municipality to be sure you're within the regulations. And if you live in a HOA neighborhood, check with their guidelines, too.

What can I grow in my greenhouse?

A greenhouse's controlled environment lets you start seeds early and extend your gardening season. This flexibility helps you easily grow fresh vegetables and herbs, flowers and tender tropical plants. In short, you can grow just about anything in your greenhouse.

How do I cool a greenhouse in summer?

Keeping your greenhouse cool in summer's extreme heat requires proper ventilation and shading. Open roof and side vents to let hot air escape, hang shade cloths to protect tender plants from intense sunlight, and run electric fans to keep fresh air moving.

How do I heat a greenhouse in winter?

Maintaining consistent temperatures inside your greenhouse is essential for protecting plants from cold weather. An electric heater is helpful to warm the greenhouse on dark winter nights.