Glasshouse vs Polycarbonate Greenhouse: Which is Better for New Zealand Gardens?

March 17, 2025

When choosing a greenhouse for your Kiwi garden, the decision often comes down to traditional glasshouses or modern polycarbonate greenhouses. While classic glasshouses have long been favoured by gardeners, tunnelhouses and polycarbonate greenhouses are quickly becoming the preferred choice across New Zealand for their resilience, efficiency, and value. 

Let’s compare these options to help you decide which will best suit your growing needs in our unique climate.

Heat Management in New Zealand Conditions

Our New Zealand climate presents unique challenges for greenhouse gardeners. Glass structures allow maximum sunlight to enter, which is beneficial during winter but can create scorching heat in summer, particularly in northern regions. Without adequate ventilation systems, plants may suffer heat stress or sunburn. Effective glasshouse management often requires investment in additional cooling solutions like roof vents, louvre windows, or shade cloth.

Polycarbonate greenhouses, by contrast, naturally diffuse sunlight while providing better temperature stability. The material’s insulating properties maintain more consistent growing conditions without extensive ventilation requirements. For Kiwi gardeners facing our variable weather patterns, this translates to healthier plants and reduced energy costs throughout the seasons.

Weather Resilience for Our Climate

New Zealand’s weather can be unpredictable—from Northland’s subtropical conditions to Central Otago’s harsh winters and everywhere in between. Glass panels, while elegant, are vulnerable to damage from hailstorms, strong winds, or accidental impacts. When breakage occurs, replacement is both costly and potentially hazardous.

Polycarbonate greenhouse panels are much more durable, particularly with the addition of Morrifield’s accessories, making them ideal for withstanding our diverse weather patterns. Whether you’re dealing with Canterbury nor’westers or Auckland’s sudden downpours, polycarbonate structures remain intact and secure, providing peace of mind for years of trouble-free gardening.

Light Quality for Optimal Plant Growth

While glasshouses offer excellent light transmission (up to 95%), this intense direct sunlight can create hotspots and uneven growing conditions. Many Kiwi gardeners find themselves adding shade cloth during summer months to protect sensitive seedlings and plants.

Polycarbonate greenhouses transmit slightly less light (80-85%) but distribute it more evenly throughout your growing space. This diffused light creates optimal conditions for most plants, promoting uniform growth without the risk of leaf burn or scorching—particularly important during our intense UV seasons.

Year-Round Growing with Better Insulation

For serious gardeners wanting to extend their growing season, insulation becomes crucial. Double or twin-wall polycarbonate offers superior thermal efficiency, retaining heat significantly better than single-pane glass. This translates to warmer nighttime temperatures in winter and reduced heating costs for year-round growing.

Glass structures lose heat rapidly during our cool evenings, often requiring supplementary heating systems to maintain stable temperatures for sensitive plants. This additional energy consumption can significantly impact both your power bill and environmental footprint.

Installation and Long-Term Value

Glasshouses can require a substantial investment, from the materials themselves to the robust framing needed to support heavy glass panels. Professional installation is often necessary, adding to the overall expense.

Polycarbonate greenhouses offer better value for most home gardeners. They’re lighter, easier to assemble, and frequently available as DIY kits that can be installed over a weekend. Many Kiwi gardeners appreciate this accessibility, allowing them to invest more in quality soil, irrigation systems, and plants rather than the structure itself.

The Verdict for New Zealand Gardens

While traditional glasshouses do offer a premium look, polycarbonate greenhouses provide practical advantages for most New Zealand gardening situations. Their superior insulation, impact resistance, excellent ventilation options and lower maintenance requirements make them particularly well-suited to our diverse climate zones.

Modern polycarbonate greenhouses have evolved significantly in design and aesthetics, offering clean lines and attractive profiles that complement any garden style. At Morrifield Greenhouses, our range combines functionality with visual appeal, ensuring your greenhouse enhances rather than detracts from your garden landscape. With additional parts and accessories like high wind kits and shelving units, you can customise your setup to create an efficient growing environment tailored to your specific needs.

Explore Morrifield’s range of high-quality, durable greenhouses and polycarbonate greenhouses. Plus, check out our parts and accessories to see how you can customise your greenhouse.