Greenhouse or Polytunnel. Which is best? The facts!

“Greenhouse V Polytunnel Cost”

Greenhouse with toughened Glass –

2.4m x 3m (8ft x 10ft) from £690.  3m x 3.6m (10ft x 12ft) from £1200.   3.6m x 5.4m (12ft x 18ft) from £3000

A Polytunnel with Thermal Anti Fog polythene, anchor plates & base rails -

2.4m x 3m (8ft x10ft) from £379.  3m x 3.6m (10ft x 12ft) from £437.  3.6m x 6m (12ft x 20ft) from £588

“Cost per sq ft Growing Space”

Greenhouse –

2.4m x 3m (8ft x 10ft) = £8.63 per sq ft.  3m 3.6m (10ft x 12ft) – £10 per sq ft.  3.6m x 5.4m (12ft x 18ft) = £13.89 per sq ft

Polytunnel -

2.4m x 3m (8ft x 10ft) = £4.74 per sq ft.  3m 3.6m (10ft x 12ft) – £3.64 per sq ft.  3.6m x 5.4m (12ft x 18ft) = £2.45 per sq ft

“Site Preparation”

Greenhouse

Must be put up on a firm, level site.

Polytunnel

A slight slope can be accommodated and even helpful in heavy soils. Slopes can be dealt with using extended foundation tubes.

“Construction Ease/Time”

Greenhouse

60% of people buying a greenhouse opt to have them installed. On average, a 2.4m x 3m (8ft x 10ft) may take a weekend to construct, or one day for an experienced fitter.

Polytunnel

95% of people buying a Polytunnel opt to erect it themselves. On average, a 2.4m x 3m (8ft x 10ft) polytunnel will take a couple of days to construct. Half a day for an experienced fitter.http://www.firsttunnels.co.uk/faqs.asp

“Cover/Glass Option”

Greenhouse

Horticultural glass, toughened glass or polycarbonate. Toughened glass is much safer as if it breaks it falls into blunt cubes.  Approximately 20% more expensive than normal glass. Polycarbonate offers best insulation but has a limited lifespan and is prone to blowing out of the fame.

Polytunnel

Standard Polythene, Thermal Anti-Fog or White Polythene. First is the cheapest and the last is primarily for plants which prefer reduced light. Thermal Anti-Fog is designed to reduced running condensation which can damage plants and improve heat retention.

“Ventilation”

Greenhouse

Cheaper greenhouses tend to offer limited ventilation, usually just through the roof openings.  This offering lower level side ventilation will maximise air changes.

Polytunnel

For up to 3.6m (12ft) long tunnels, a door at either end will provide adequate ventilation. (A sliding door also gives you greater control over ventilation) For longer polytunnels, net side ventilation can be added at one or even both sides.

“Cons At A Glance”

Greenhouse

Site MUST be level. Get less growing space for your money. More expensive. Too much direct sunlight can cause problems.

Polytunnel

Water collection can be trickier. Prone to damage.  Ventilation less refined.

“Pros At A Glance”

Greenhouse

Looks good. Long life. Water collection easy. Automatic ventilation possible.

Polytunnel

Cheaper. The bigger you go the cheaper it gets. Suitable even for sloping sites. Straight forward to construct.

“Conclusion”

For many gardeners, a greenhouse is not just somewhere to grow your plants – it is a status symbol!  So if appearance was a consideration a Greenhouse would be Top. However, where practical growing space is required, getting much more growing space for your money and the fact a polytunnel is easier to construct - A polytunnel is likey to be the preferred purchase!  “Well done to the Polytunnel”