How to set up a greenhouse

Aside from the ability to control the temperature, there are a number of other reasons for you to give a greenhouse a go. These include:

• If you’re in a climate that swings this way and that (like the vast majority of the UK) one of the hardest things in gardening is trying to give your flowers and plants any kind of consistency. A greenhouse will allow you to set a constant growing environment almost free of fluctuations.
• Seasons don’t matter. A good greenhouse will enable you to change the environment as you see fit, meaning that you’re not limited to summer plants in summer, spring flowers in spring, etc. Grow whatever you want, whenever you want!
• Good versatility. Greenhouses can be used to create more or less any gardening environment, from a peat bog to a sandpit. What’s more, it will enable you to do this in virtually any external climate.
• General protection. There remain few things more likely to damage your garden than good old fashioned wind, rain and snow. A greenhouse offers the perfect all-round protection from the elements.

There are a lot of greenhouses available; it can be pretty tough trying to decide which version will suit you best. Here are some of the major decisions you need to take into account.

Location, location
The only downside of the greenhouse versatility listed above is that they can be a bit fussy about where they actually go. You’ll need to pick an area of your garden that gets plenty of light, but still has a little bit of protection from the wind. The greenhouse will also need to be kept away from any trees, as falling leaves will dirty the frame.

If you’re planning on heating the greenhouse electrically, then you’ll want to get it as close to the house as possible, as it will be cheaper to have the electricity installed. At least 2ft of access space around the greenhouse is usually necessary for cleaning and making repairs.

Finally, the greenhouse will of course require a tough, durable flat base – no putting it straight onto the soil! Paving slabs are the perfect choice, and they can be wetted in the summer in order to keep the air humid.

Heating
The most efficient heating solution for a greenhouse is an electric fan heater combined with a propagator and a thermostat. Bubble insulation also provides additional warmth at a lower cost. Whilst you don’t have to have additional heating, it’s nearly always useful, and it makes sense to plan for it in advance.

Glazing
Whilst greenhouses are typically thought of as being just glass, modern models are actually now available in other materials, such as plastics and polycarbonates. There are pros and cons to all three. Glass is the clearest, and lets in the most light overall. It also lasts the longest and is the most easily replaceable in terms of single panels. Of course, the main downside is that it’s also the most breakable by some distance. Plastics and polycarbonates are far less likely to break, but don’t let light in as effectively as the glass. They’re often the more expensive options.

The other key thing to consider is that glazing will have different insulation properties, so some may be more suitable for some climates than others. Polycarbonate sheeting tends to insulate better so less heat will be lost from your greenhouse. This will be beneficial if your garden is in a particularly cool area.

A good greenhouse really needs to be at least 6ft wide, and 8ft if you want staging on each side. Any smaller than this and you’ll struggle to work within the space. Frames are typically made from either aluminium or wood.

Aluminium frames are usually cheaper by as much as a quarter to a third, compared to wooden ones (though colour coating can up the cost) and are pretty much maintenance-free. If you only want to buy one greenhouse, then aluminium is probably the sensible choice.

Wooden frames usually look better in a visual sense – they’ll look the part amongst all the wooden furniture – but they can rot over longer periods of time. If you want real style, then wood is the best option.

All greenhouses need vents of some kind in order to ensure optimal growing conditions. Overall, the size of the vents should reach at least a fifth of the floor area. The bigger the greenhouse, the more ventilation will be needed.

The most popular type of greenhouse is the freestanding one – they come in all sizes and shapes, and are not reliant on any other structure for support. Some of the main types of freestanding greenhouses include:

High tunnels. These are more common in larger gardens and feature large hooped frames covered with plastic. If you’ve got a large garden and want to get the most growing space for the best price, a high tunnel is a great choice.

Metal frame and poly-panel kits. These are the most common and most accessible forms of greenhouses for the beginner gardener.

Wood frame. As we’ve noted above, wooden frames can look really elegant. They’re not for everyone, but some people won’t be without one! Ideal if you have a higher budget.

Of course, it might be that you don’t want a freestanding greenhouse. Attached and lean-to greenhouses – ones that attach to an existing structure such as the side of the house – can share in the solar heat with the main structure – this is ideal in locations where there are lots of sunny but cold days.

Cold frames, mini greenhouses and growhouses are brilliant alternatives to a full-sized greenhouse if cost and space are limited. These tend to be significantly cheaper than their full-sized siblings and are also much more mobile, meaning you can move them in-line with requirements for the crops you’re growing.

As well as the frame, the base and the plants, you’ll also usually require some extra accessories that are not quite essentials but will make very good additions to your greenhouse overall. These include:

• Shade cloths. These are an invaluable (and surprisingly inexpensive) tool that are wrapped over the frame of the greenhouse, shading it. Essentially, it’s a very effective way of simply lowering the inside temperature without worrying about fans or ventilation.
• Hand watering wands. When working with young sprouts, it’s important to not use too strong a water spray. Watering wands are available that will let you adjust their nozzles so you can reach the back of seeding trays and different shelf heights.
• Potting bench. Another essential during those early growth days; you need a firm surface on which to work, a suitable container in which to sweep excess soil back into the bag. Say hello to the humble potting bench! Even a cheaper model can be invaluable.
• Irrigation systems. If you’ve got a bit more budget, then an automatic irrigation system can be an invaluable accessory as it will enable you to ensure that your seedlings always get the right amount of water.