Don’t bake your greenhouse plants in the summer sun

Traditional aluminium greenhouse

The maker of one of Britain’s most iconic greenhouses has given some timely advice about keeping plants cool in the summer sun.

Paul Smith, the Technical Director of Griffin Glasshouses, producers of bespoke and the National Garden Scheme range, warns that even in overcast weather the temperature inside can reach levels that are harmful to plants.

“Small structures are most at risk because the volume of air compared to the glass area is small causing it to heat up very quickly. The best rule is that a greenhouse should have 25% of the floor areas as ventilation. Our structures are deliberately high because this has the effect of a chimney drawing the hot air up and out through the vents,” he explained.

Paul’s top tips are:

  • Water last thing at night and early in the morning as this reduces the evaporation of moisture and also prevents water droplets forming on foliage and risking scorching.
  • If you are considering greenhouse shading reflective material is best as this drives the heat away from the greenhouse. Darker colours absorb heat, sending it back into the building Whatever you use, make certain the shading does not block the ventilation.
  • If you do not have shading there are proprietary materials that can be painted or sprayed on to the inside of the glass. This is easily removed in the autumn.
  • Don’t forget that the doors can be a major source of ventilation and, if possible, they should remain open at night.
  • Vines are an excellent and natural form of shading.

“Remember, if you are working in your greenhouse in the sun and it’s too hot for you, it is most probably the same for your plants,” warns Paul.

Bespoke greenhouse manufacturer cuts costs by design innovation

Small aluminium greenhouse

A new design initiative by the UK’s leading bespoke greenhouse manufacturer that was launched at the Chelsea Flower Show cuts the cost of greenhouses by several thousand pounds.

Griffin Glasshouses has redesigned some of its structures so that insulated aluminium panels reach down to floor level, removing the need to have brick footings.

“Brickwork can cost as much as a third of the overall cost of a greenhouse,” says Griffin Glasshouses’ Technical Director, Paul Smith. “By continuing the structure to ground level the visual solidity of the base is achieved without the cost of brickwork.

“A recent greenhouse that would normally have cost £40k would have actually been £10k cheaper because we did not need the brickwork. The other major advantage is that it speeds up the whole installation programme,” adds Paul.

Griffin Glasshouses has not had to reinforce their aluminium frames to accommodate the new designs. All the greenhouse structures are produced at the company’s facility at Ropley in Hampshire. Some of the bespoke greenhouses will still require brick footings.

Folding greenhouse staging maximises space

Folding greenhouse bench

Almost all Griffin’s greenhouses can now be fitted with folding greenhouse staging to give more growing space during the season.

The company’s patented “fold away” bench design provides ideal accommodation for seed boxes and pot plants but, when the growing season arrives, can be simply folded down to reveal the growing area.

“It is a very simple but highly effective solution, particularly in smaller greenhouses where space is at a premium,” says Griffin Glasshouses’ Technical Director, Paul Smith.