I have a polytunnell 25′ x 14′ approx with one entrance door. Plants tend to wilt from the heat on warm days even though the door is left open. Do I need a second opening at the opposite end of the polytunnell for air to circulate or can I do anything else to remedy this problem. Plants are watered every evening after sun down.
If the polythene is held by a rail at soil level, as some are, the soil can be dug out under the rail to allow air in along the length of the tunnel. Some tunnels have the polythene buried along the sides to hold it down and it is not possible to dig out these.
Plants should be grown in the open soil of a polytunnel and are much less likely to wilt, especially if adequate amounts of moisture-retaining humus are applied.
Shading material is a possibility, ideally placed on the outside of a greenhouse but this can be hard to do.