BCSS Macclesfield & East Cheshire Branch

Newsletter September 2007 - Some thoughts on scorching

In the June issue of our Newsletter Alasdair refers to the problem of protecting our plants from scorch during the summer, so it seems strange to be writing this during another wet July day. Looking at Teletext this morning (26th July) I see that the Met office is reporting that this year's early summer, (May, June and July), is the wettest since records began 240 years ago! However, back to scorch.

After our dull cloudy winters I find that plants are very vulnerable in the early spring sunshine which can be quite strong during April (between showers) and early May, before the plants are fully acclimatised to the increasing light intensity. The other time that I find plants most at risk of scorch is during the heat(?) of summer, when the air is still and oppressive and a thunderstorm is brewing. So what to do about it?

A good temporary measure, (on Alasdair's list) is newspaper over the plants, but this needs weighting or clipping down if it is not to blow about the greenhouse when a breeze springs up. Equally useful for individual tender plants are pieces of kitchen paper towel roll. These can be carefully pressed on to spiny plants so they stay in place, careful removal is also required or the spines may be damaged. I also use small pieces of paper towel to cover small trays of Conophytums for early spring protection. Care should be taken with this method to ensure the plants are not enclosed too much, or heat could build up under the paper and the plants may cook if the sun is very strong, although I have not had this problem. Some years ago I bought a 36-foot roll of green plastic mesh. My greenhouse is 10 feet long, so cut into 3 lengths of 12 feet this fits with a one foot overhang at each end. I put one length along the ridge and along each side of the roof so that the greenhouse is covered. All this is held in place by plastic spring pegs attaching to the maim glazing bars of the greenhouse and works well for the times when we get prolonged sunny weather. Leaving the door open helps, giving plenty of ventilation, but keeping out various neighbourhood cats proved to be a problem. I made an open frame from 2 x 1 inch timber to exactly fit into the door opening. I covered this with plastic clematis netting (2 inch square mesh) from the garden centre, tacking it to the wooden frame with galvanised staples. This fits tightly into the door frame once the door is slid back and I put it in place ion the spring, once the risk of frost has passed. It is easily pulled out for access and it stays in place day and night till autumn and the renewed risk of frost. With the vents both fully open very good flow through ventilation is achieved and the risk of scorch minimised. An automatic vent opener proved unreliable and eventually the mechanism disintegrated. I found it in pieces on the greenhouse floor, so now I open and close the vents manually during spring and autumn and leave them fully open night and day during the summer months.

Trevor Shannon