Greenhouse FAQs

Many of our customers are confused by the huge choice of greenhouses that are on offer and their relative merits. In this article we answer your most frequently asked questions.

We know that buying a greenhouse isn't just a spur of the moment purchase and that you'll want a model and size to perfectly match your outdoor space. As we've been around since 1952 and have been selling greenhouse online since 1999, you can bet we've been asked almost every question to do with a greenhouse, and we've collated the most common questions below.

Are Timber Greenhouses Better Than Aluminium?

Neither type is 'better' than the other, they both have plus points and disadvantages.

What Are The Advantages Of A Wooden Greenhouse?

Many people prefer timber as it's a natural material and whose good looks seem to blend easily into the garden landscape. The major horticultural advantage is that wood retains heat, the interior temperature is more stable and, if you choose to heat the greenhouse, fuel costs will be less.

Are There Many Disadvantages?

Wooden greenhouses tend to be more expensive. It is often said that they require more maintenance although the timber used in the greenhouses we sell is very durable, it will be either traditional cedar, dip or pressure treated timber, or heat treated ThermoWood which has practically all moisture removed. You may also have heard that they are heavy and difficult to erect but an installation service is offered as standard for Swallow and as an option for Gabriel Ash greenhouses.

Why Should I Choose An Aluminium Greenhouse?

They tend to be cheaper to buy. Low maintenance and rust resistance is guaranteed by modern manufacturing techniques, there is no need for paint or preservatives of any kind. Lightweight, aluminium greenhouses are easy to assemble or you can choose to take advantage of an installation service. With more glazing, aluminium greenhouses let in more light.

What's There Not To Like?

Heat loss is noticeable when compared to their wooden counterparts so fuel costs will be higher if heated over the winter and, although green blends in well with the garden, many gardeners just prefer the appearance of traditional timber.

Can I Choose Different Colours?

Normally aluminium greenhouses are either silver or green although certain manufacturers offer black, brown, white and terracotta. Some of our wooden greenhouses can be optioned with a colour finish, others can be painted or left with an attractive natural appearance, cedar wood, for example, will age to a lovely silver grey.

Do Both Wooden & Aluminium Greenhouses Need A Base?

Yes, you cannot locate either directly onto soil or turf. Some greenhouses have an integral base, others offer them as an extra. You can, if you prefer, build one yourself using timber, slabs, concrete or bricks.

Freestanding Or Lean To?

Freestanding greenhouses let in more light than lean-to's, and have more growing and working space with room for plenty of staging. Lean-to greenhouses are great if you only have a restricted outside area or small garden. They are unsuitable if you have only a north facing a wall and light levels are less, that's why the back wall has been traditionally painted white.

Do I Need To Heat A Greenhouse?

Heat will determine the number and variety of plants you are able to grow and keep protected over the winter. It will extend the season and enable early sowing.

What's The Best Position For A Greenhouse?

An easily accessible, sheltered, and well-drained site that gets lots of sunlight. Install the door away from the prevailing wind with the longest side facing south. Lean-to's should be on a south facing wall. A water source and mains electricity would be useful to have close by.

What Glazing Should I Choose?

Horticultural glass is the cheapest option, it has good light transmission but easily breaks into shards and is not suitable if you have children. Toughened or safety glass is a better choice as it again lets through plenty of light but disintegrates rather than breaks. Polycarbonate is the safest alternative but more expensive, it offers better insulation, 85% transmission and good light diffusion.

What Are The Most Useful Accessories?

A rainwater collection system will provide a constant source of fresh water that plants prefer over tap water. Mesh, blinds or shading paint during hot weather. Capillary matting or an automatic system will make watering easier. A minimum/maximum thermometer to accurately control temperature. Automatic vents for when you are away from home.

Is Size Important?

A modestly sized greenhouse is better than none but it's always best to buy the largest one you can afford as it will quickly become filled with all sorts of plants plus gardening equipment and our previous customers always tell us that they wished they had bought a larger size so that they could grow even more of their favourite produce!

Will I Need Staging?

Yes, it will always come in handy for sowing seed, overwintering plants and many other tasks.

How Much Ventilation Is Required?

To keep the temperature below 80°F there should be 1sq ft of ventilation for every 10sq ft of ground area. Louvres, as well as roof vents, are effective at achieving a good flow of cooling air through the greenhouse, and simply opening the door is also important during hot weather.


A greenhouse surrounded by plants and flowers.