How to Set Up a Greenhouse

A greenhouse is a fantastic way to extend your growing season, protect plants from harsh weather, and cultivate a variety of crops year-round. Imagine being able to enjoy fresh tomatoes, peppers, or even delicate herbs long after the first frost. Whether you’re dreaming of an early spring harvest or simply want to provide your plants with the perfect growing environment, a greenhouse offers endless possibilities. From the warm, inviting temperatures inside that mimic the summer sun, to the protection from cold winds and unexpected frosts, a greenhouse allows you to cultivate a wider variety of plants, no matter the season. If you’re considering setting up your own greenhouse, there’s plenty to consider. Here’s what you need to know to get started and make the most of this rewarding gardening addition.

Positioning

Before buying a greenhouse, the key decision is where to place it. The location affects both plant success and the structure’s longevity. Whether you want your greenhouse visible or tucked away, be mindful that it will likely attract attention from visitors.

For optimal light, position your greenhouse away from trees or shaded areas. The best spot will capture morning sunlight, as plants benefit from early light for photosynthesis. Aim for a North-South or East-West orientation: a North-South alignment offers even sunlight on both sides, while East-West gives the sunnier southern side to sun-loving plants like tomatoes and cucumbers, with the northern side offering shade for other plants.

Measure the site carefully and mark it out with string to ensure the greenhouse fits. Choose the largest size you can afford, as you’ll quickly outgrow a small one. Finally, consider water access—using runoff from gutters can be an efficient solution if water is scarce.

Choosing the Right Greenhouse

There are many types of greenhouses, from small cold frames to large walk-in structures. Your choice depends on space, budget, and what you want to grow. Look for a model with good ventilation, sturdy construction, and adequate insulation for your climate.

Materials: What’s Best for You?

When choosing materials for your greenhouse, it’s important to consider the benefits each option offers.

Wooden frames provide a classic, natural look and offer good insulation, though they do require regular maintenance to prevent wear and tear. If you’re after a low-maintenance option, metal frames, particularly aluminium, are durable and rust-resistant, needing little upkeep over time.

If you’re considering a more affordable and flexible option, polytunnels are a great choice. These structures are made with flexible plastic sheeting, usually polyethylene, stretched over metal or galvanised steel frames. Polytunnels are easy to set up, cost-effective, and provide excellent protection from the elements. They offer better insulation than open-air gardening while allowing for a high level of airflow, making them ideal for growing a variety of crops. They also have the advantage of being easily expandable, which makes them a great option for gardeners looking to increase their growing space over time.

Essential Features

Good ventilation is essential for keeping your greenhouse environment healthy. Without proper airflow, you risk overheating and creating conditions for disease to spread. Consider installing roof vents, side vents, or automatic openers to maintain good circulation.

Insulation is key in colder weather, so options like bubble wrap or thermal screens can help trap heat and maintain a steady temperature inside your greenhouse.

In warmer climates, shading your greenhouse can prevent overheating and protect your plants from harsh sunlight. Shade cloths are a practical solution for reducing the amount of direct light your plants receive, helping to keep them cool and happy.

Setting Up Your Greenhouse Interior

A well-organised greenhouse maximises space, keeps plants healthy, and makes gardening easier. Here’s a guide to help you set up your greenhouse:

Shelving and Benches
Install sturdy shelves to make the most of vertical space, perfect for seed trays, potted plants, and smaller tools. Consider tiered or hanging shelves to keep plants at different heights, ensuring better light exposure. Foldable or adjustable benches can be a great option if you need extra space for larger projects, and they can be tucked away when not in use.

Growing Beds and Containers

Raised beds are a great choice for improving drainage, better root development, and easier planting. These can be built using wood, bricks, or stone, and they save you from having to bend over too much. Large containers or grow bags are flexible, allowing you to move them around to adjust your layout. Vertical planters or hanging baskets are ideal for growing trailing plants like strawberries or tomatoes, which can save valuable floor space while making use of your greenhouse’s height. Stackable or modular planters are also a great option for making the most of smaller spaces.

Irrigation and Watering

Watering your plants can take a lot of time, so consider setting up a drip irrigation system or soaker hoses for consistent, hands-off watering. These methods are efficient and ensure water reaches the roots without wasting it. For low-maintenance options, self-watering planters are perfect for keeping moisture levels consistent. Keep a rain barrel or other water source nearby for sustainability, and to make watering more convenient. If you prefer hand-watering, a watering wand or a hose with an adjustable nozzle will give you more control, allowing you to target specific plants.

Temperature and Humidity Control

Maintaining the right conditions in your greenhouse is crucial. Use a thermometer and hygrometer to monitor the temperature and humidity, so you can adjust accordingly. If you live in a cooler climate, small electric heaters, heat mats, or thermal mass (like water barrels) can help regulate temperature and keep your greenhouse warm during the colder months. For tropical plants, misting systems or damp gravel trays can help maintain the humidity. Ensure proper air circulation to prevent excess heat buildup by opening vents or using fans. In the warmer months, shade cloths or reflective paints on the roof or sides of your greenhouse can help keep things cooler.

Storage and Work Areas

Organising your tools and supplies makes gardening more efficient. Dedicate a corner for essentials like soil, fertilisers, gloves, and tools. Install hooks or a pegboard on the walls to keep small tools accessible and out of the way. A potting bench provides a convenient space for seed starting, transplanting, or potting up new plants. Labelled storage bins are helpful for keeping seeds, bulbs, and gardening supplies neat and easy to find. For added convenience, use stackable crates or rolling carts, which can be moved around the greenhouse as needed. Don’t forget to keep a notebook or whiteboard for recording planting schedules, maintenance tasks, and observations on plant growth. It’s a great way to keep track of what works and what doesn’t.

Power Up

For a more advanced setup, consider running water and electricity underground from your house. Some gardeners use heated propagators, which can be thermostatically controlled to raise the temperature by about 10° above the ambient temperature, helping to keep the greenhouse frost-free.

Remember, both water and electricity installations should be done by a qualified electrician and plumber, so factor these costs into your budget.

What Can You Grow in a Greenhouse?

Now, the fun begins! Greenhouses are perfect for growing plants that struggle outdoors or are limited by the changing seasons. Herbs like basil thrive in these environments, along with tomatoes, peppers, and cucumbers—many of which can be started from seed. They enjoy temperatures between 12-29°C.

You can experiment with exotic and ornamental plants. Geraniums and ferns are popular choices, and with careful temperature control, you could even try growing orchids.

For cooler seasons, crops like lettuce, broccoli, peas, and carrots do well in unheated or shadier greenhouses.

Your options are only limited by your imagination! Start with the easier plants, gain experience, and before long, you’ll be wishing for a bigger greenhouse!

Further Tips and Reading

Water your plants in the morning when it’s cooler and the sun is less intense to prevent burning. Water at soil level to reduce the risk of fungal or bacterial issues.

Ensure your greenhouse is well-ventilated, especially on hot days. Also, repair any broken glass or torn plastic, and remove any leftover crops and weeds to avoid attracting pests.

Pest control is essential. Greenhouses can attract pests, and some insects may even take refuge for the winter. To keep them in check, consider using whitefly traps, which attract bugs and keep them away from your plants. Watch the video below for how to make your own whitefly traps;

While we can’t cover everything in one article, we hope this gives you a great start to your greenhouse journey!