Last Wednesday someone asked about heat stress in roses, so let’s start off there. The first signs of stress is (like in humans) drooping or wilting of the newer growth. Do nothing and the leaves and newer canes will show some signs of sunburn – reddish-brown edges to the leaves and browning on the canes. Then the bush will start to drop its leaves, in an effort to save the plant – and if left the bush will become completely defoliated. At this stage the plant is starting to die unless drastic measures are taken. Take the time to have a look at Colorama in Petal B for a bad example of heat stress. Lots of leaves on the ground and sunburnt canes throughout.
The remedy is to get water to the roots by whatever method you can. It won’t hurt to also give the plant a thorough overhead soaking as plants can take up some moisture through the leaves. Make sure the water is soaking in by giving the ground some wetting agent. In extra dry weather, the ground becomes hydrophobic and the water will run off rather than soaking in.
