The Modern Greenhouse Guide

Article: Mina Phillips

Whether you require a basic greenhouse for your plants to live in or you want to get creative with the architectural design of your home, a greenhouse is an essential backyard requirement for any serious gardener. There is a growing interest in incorporating a greenhouse into home designs, with homeowners around the world taking it as an opportunity to save money on both power bills and food. 

What is a greenhouse?

Strictly speaking, greenhouses are clear structures in the shape of a house, which house and protect plants. They provide gardeners with an achievable way to grow plants which may not ideally be suited to their country’s climate, and also allow plants to grow year-round. 

What is the difference between a greenhouse and a glasshouse? 

Essentially, glasshouses and greenhouses are the same. They serve the same purpose but are sometimes referred to as one or the other, depending on regions and materials. In Europe, “glasshouse” is generally the more popular term, while the United States generally call them “greenhouses”. 

Some companies may also differentiate between a “greenhouse” and “glasshouse” depending on the materials that are used. Glasshouses will be strictly made out of glass while greenhouses may be made out of glass or plastic film. There are benefits to both materials. Plastic film provides plants with a higher humidity level than glass, while glass will provide plants with more light than plastic film. 

Why do I need a greenhouse?

One of the biggest gardening struggles is planning a garden around the seasons and waiting for the right season to grow your favourite plant! A greenhouse provides a solution to this. Because of the warmth that greenhouses provide, plants that could usually only grow in summer can be grown year-round. This doubles your planting options in the colder months and also provides a way to save on food costs. 

Another bonus to greenhouses is that they protect plants from harsh weather and pests. They can also add value to homes and, from a renovation perspective, can be a creative solution to warming up homes and growing food in cold climates.

How to design a greenhouse 

Greenhouse designs are becoming increasingly innovative. While a small structure in the garden might be the first thing that comes to mind when you hear mention of a greenhouse, there are many creative ways to incorporate a greenhouse into residential and commercial designs. In Iceland, a greenhouse restaurant named Friðheimar grows and serves tomatoes year-round, despite Iceland's cold climate. In Sweden, one couple built their home within a giant greenhouse so that they could enjoy nature and warmth throughout the year. When it comes to greenhouse designs, there really are so many options.   

What can greenhouses be used for? 

If you’re looking for some greenhouse design ideas, feel free to take inspiration from the following:

• Basic greenhouse

If you simply want the option of being able to grow your favourite plants year-round, look no further than a standard, high-quality greenhouse. 

• Greenhouse conservatory

Create a space where you, your plants, friends and family can soak up the sun and enjoy brunch, a cup of tea or a night of indoor stargazing. 

• Wintergarden

Why not go all-out and create a beautifully landscaped garden that you can enjoy throughout the year with your family and friends? 

• Greenhouse kitchen

Turn your kitchen into a jungle and have all of your fruits and veggies within easy reach by having an outdoor kitchen in your greenhouse.

• Greenhouse art studio

Studies have shown that nature increases creativity, so why not build a greenhouse art studio where you can improve your talents?

• Indoor swimming pool

Give yourself and the kids a place to stay active in the winter by installing a swimming pool inside a greenhouse. Include a few tropical plants and a spa pool and you’ll have the perfect winter escape!

Greenhouse sleepout/airbnb

Is your property located in a private location with a stunning view? Provide your guests with a greenhouse sleepout that will make the most of the beautiful surroundings.

Things to consider with your greenhouse:

Your planting plan

First things first, what plants are you wanting to grow in your greenhouse? Make a list, noting down how much size each plant is likely to need once it is fully grown.

Heating

During the design stage of your greenhouse, focus on using high quality materials that will provide good insulation. As you approach the colder months, you will need to start thinking about ways in which you can retain heat and what heating appliances will work well within your space. You can read more on this in Can a greenhouse be used in winter? 

Your layout

Now that you know what you will be including in your greenhouse, you can start thinking about your layout. Think about what plants will work well next to each other and where you will require pathways or stepping stones to easily access them. When planning this, ensure you have left plenty of room for plant to grow to their full size. Storage space also needs to be factored in. Once you have a rough idea of your layout, a landscaping specialist will be able to advise you on the right greenhouse size for your design and budget.

Indoor/outdoor flow

Location is an important consideration. As well as pinpointing a level section of land to place your greenhouse on, think about where would be the most ideal placement. If your greenhouse is going to be full of edible plants, you’ll want it to be close to your kitchen. Is there room just outside the kitchen for a greenhouse to be built? Is renovating your kitchen into a greenhouse an option?

Irrigation

Finally, don’t forget to keep your plants hydrated! The easiest way to achieve this is through irrigation. The experts recommend drip-line or soaker hose irrigation for best results. There are plenty of automated irrigation systems on the market, making it easy to maintain your garden on a busy schedule or when you’re on holiday. A great place to learn all about how to use irrigation is in the Guide to Watering your Garden

Can I add on a greenhouse as a home extension? 

You can indeed. Zones can work with you alongside our sister company Refresh Renovations to provide you with your ideal design, build and planting plan. For more information on the costs involved, check out Greenhouses on a high-end budget.

Greenhouse Checklist

We have added a cheklist that you can download and use when creating your greenhouse.

Can a greenhouse be used in winter?

To help your greenhouse serve its purpose, the space will require a little more TLC in the colder months. Your greenhouse can absolutely be used in winter, and a few key choices will help your plants to thrive within their glass or plastic-film home. 

How should I heat my greenhouse?

The first step to keeping your plants warm year-round is to have a high quality design drawn up for you, focusing on quality materials and sealants. From there, think about insulation. In winter, you’ll want your greenhouse to bring in as much warmth as possible during the day and retain much of it during the night. Closing doors and windows later on in the day to keep the heat in is a good place to start - keeping in mind that ventilation during the day is key to avoiding mould and overheating. Installing a unit, such as a barrel of water, that will soak in the daytime heat and radiate it throughout the night is recommended. Twin wall glazing can also make a big difference. 

Looking at the interior, heat pads can prove helpful when placed under young plants. But you’ll also need to think about more general heating sources. This might be through a gas or electric heater. Keep in mind that if the power goes out, so will your electric heater, and your plants could suffer for it.    

Solar panels         

A solar powered greenhouse is the ultimate sustainable solution to powering your heating appliances on an ongoing basis. Solar panels will save you a significant amount of costs in running the greenhouse long-term. It’s a great way to utilise your land without damaging the environment. You can use pretty much any type of solar panel on a greenhouse, with monocrystalline solar cells being the optimal (and accordingly, the most expensive) choice.

Selecting plants that will thrive year-round

Generally, any plant that usually wouldn’t survive through winter will do well year-round in a greenhouse. Opt for summer vegetables such as tomatoes, cucumber, capsicum, leafy greens and chillies. You can enjoy your favourite fruits from January through to December, with strawberries, grapes and citrus fruits being particularly inclined to thrive in a greenhouse. Find more detailed instructions in the Grow Your Own Fruit and Vegetables article When it comes to flowers, greenhouses make life easy for orchids, roses and African violets - to name a few.

If you're a keen gardener, you will want to check out the Annual Garden Maintenance Calendar

How much do greenhouses cost in NZ? 

There are both initial and ongoing costs involved in owning a greenhouse, and it’s important to understand these before going ahead with the design and build. Depending on the size of your project, you may need to factor the costs of labourers, landscape architects, council permits, materials, plants, irrigation, solar panels and heating into your design.  

Greenhouses on a budget

If you have a small budget to stick to, a standard greenhouse which will keep your plants alive year-round is probably what you’re after. Designing this from scratch will provide you with the best layout and placement for your space and planting plan. For this, you will require a landscape architect. Once you have your design, you will also need to think about the materials you will need and the labour required to both build the greenhouse and carry out any landscaping work within or around it. Consider the following costs and whether they will apply to your greenhouse design and build, and then budget accordingly.

Landscape architect: $80 - $150+ p/h

Building and landscaping labour: $20 - $40+ p/h (standard residential greenhouses usually take a minimum of 2 days to build)

Materials:

• Polycarbonate greenhouse materials: Approximately $1,500 - $2,000+ for a small scale, 6x6ft - 6x8ft greenhouse, all materials included
• Glasshouse materials: Approximately $2,500 - $3,000+ for a 6x6ft - 6x8ft glasshouse, all materials included
• Lighting/electrical: Approximately $2,000+ for wiring and light installations
• Council permits: Required for greenhouses with a floor area exceeding 10m2. Checking in with your local council or landscaping specialist before going ahead with the build is recommended.
• Basic irrigation: Affordable irrigation systems can be purchased from stores such as Mitre 10, with drip lines costing around $2 per metre.
• Soil/potting mix - Soils and potting mixes usually cost between $7 - $20 per litre
• Plants - The cost of your plants will vary depending on your choices and taste. You could end up spending anywhere between $10 - $40+ per plant. Growing from seed is generally very affordable. 
• Heating: Specially designed electrical greenhouse heaters can be found for around $200, which will work well for residential greenhouses.    

Greenhouses on a mid-range budget

If you are an avid gardener ready to invest in a successful, long-term greenhouse, be prepared to pay a little more for a durable and amply-sized greenhouse. To get an idea of what your greenhouse could cost, take a look through the basic costs involved and then factor in the following:

Materials:

With a bit more room in your budget, opt for a spacious glasshouse. All materials included, costs for a 10x12ft - 10x16ft glasshouse will start around $6,000 - $8,000. 

Solar panels: With solar panels, you have the option of having the panels installed either on your greenhouse or your home. Installing the panels on your home is sometimes the most efficient use of energy; your greenhouse can then be wired up to your home. Solar panel prices have dropped in New Zealand in the past few years, and for a standard 3kW system installation you can expect to pay around the $9,000 - $9,500 mark. This includes 10 panels and the full installation.

Irrigation: The downside to greenhouses is that the humidity can cause soil to dry out very quickly. For this reason, it’s important to have an irrigation system. Drip lines or soaker hoses are the recommended way to go, and there are some great automation systems on the market that can pick up on moisture levels, watering your plants as needed. Moisture sensors can be purchased for around $150 - $250, excluding installation.

Greenhouses on a high-end budget

If budgeting isn’t an issue, you can create a greenhouse design that is ideal to your home and wishlist. Adding a greenhouse onto your home as a kitchen or conservatory is ideal, as your plants can be easily accessed whatever the weather. 

Renovations/extensions: Depending on the size of your new addition, set aside at least $10,000 - $20,000 for materials. On top of this, you will need to factor in demolition costs as well as the costs of hiring a project manager and labourers over a 2-6 month period, depending on the size of your project. All up, this could add up to $40,000 - $60,000 or more.

Landscaping: A fully-landscaped winter garden, including design, planting, irrigation, water features, lighting, garden screens and hard landscaping might cost you within the region of $40,000 - $100,000+.  

Additional features/appliances: With your greenhouse extension installed, you can focus on furnishing and decorating the interior. This may be with bespoke furniture (anywhere between $500 - $2,500+ per piece) or an outdoor kitchen installation ($20,000 - $40,000+).

Resource/building consent: The cost of resource and building consents will significantly vary from project to project and are best discussed with a construction manager or renovation specialist. 

*Costs are rough estimates only. Zones recommends consulting a landscaping specialist to attain a project estimate accurate to your specific project. 

Let’s discuss your project!

If you have some ideas surrounding your landscape and garden, get in touch with Zones today. We’ll book you in for a free consultation and create a design that meets your budget and ideas