SOME LIKE IT HOT (BUT NOT TOO HOT)
Here’s how to cope with high temperatures in polytunnels
Temperatures within the polytunnels are sometimes unbearably hot to work in and I often think how amazing the vegetables are to suffer such searing heat. In my small tunnel I’m fortunate that I have wind up polythene curtains along both sides. On the outside there’s a fine mesh to prevent flies and insects from getting in while the polythene curtain is on the inside. I also have two doors at the far end, so all this allows plenty of air movement within. Get yourself a good maximumminimum thermometer to monitor temperature fluctuations. But what should you do when it gets hot and how do plants cope? When it gets too hot, just like we don’t feel like food, so the plant doesn’t take up food as well. It’s important not to feed the plants during the hot weather, but make sure that the growing media they are in is kept moist. The danger is that if you feed during such constantly hot weather the plant won’t take it up. The consequence of that could be that the feed will remain in the growing medium and when the temperatures drop, and you feed again, you’ll have a double dose of food. The conductivity will be too high, and the plants won’t take any of the nutrients up. A fan is always useful but whatever you do don’t try cooling plants down by spraying them over with cold water. For something like leeks, it would just sit between the flags and cause major problems to the barrel. The other problem with excess heat is physical damage. In leeks, excess heat can burn through the epidermis of the flag or leaf and cause it to bubble up. This makes the epidermis so thin that it totally burns out. To prevent this you need to have a cover just over the flags and I use some fleece that I drape over them to prevent this from happening. ■ Follow me on Twitter as I grow a range of different vegetables for exhibition – @medwynsofangles.