In a recent blog post on Hot Weather Rose Tips, I mentioned I give my roses a bath during the heat to cool them down and take some stress off the leaves. It also washes dust away when there is a long spell of no rain like we are currently experiencing here in the upstate of South Carolina.
In the comments on that post a reader correctly pointed out that too much moisture on the leaves can lead to blackspot. We’ve all seen this during periods of constant rain and no sun. However, my own experience has led to the discovery that overhead watering timed right might actually reduce blackspot. Notice I said “timed right”. That is the key.
I once learned from some with knowledge of such things that when a blackspot spore lands on a rose leaf it takes about twenty-four hours to actually attach to the leaf. Why is this important? Because it means you have a twenty-four hour window to wash the spore off the leaf before the actual infection begins.
At my old rose nursery on sunny days I used to turn on the sprinklers in the retail area for about 5 minutes right around noon time. We did this to not only give them a bath but also to see if would help reduce disease. This was in an area with hundreds of roses in 3-gallon pots packed in pretty tight.
It worked. I noticed a reduction in blackspot, we had to spray far less and eventually stopped spraying chemicals all together when we went to an all natural care program. That noon time/sunny day bath still remains part of my chemical free care program here on our farm.
I’m not saying this will work in all parts of the country but for me, and for many others who have done it, there is some disease control. Try it in your garden, around noon, only on a sunny day and only for about 5 minutes and see if it helps.
I realize it’s contrary to almost everything written on roses but hey for me, it works.
Speaking of watering here is an article on the Fine Gardening Website on some great watering tools. Click Here to go to the article.