This weekend, I applied Dormant Oil to all of my roses. This is the best organic pest protection that you can give to your roses, as it smothers over-wintering insects and their eggs. As I wrote in a post last year:
“The dormant oil is horticultural oil diluted in water. Horticultural oil is available at most nurseries. As a dormant spray, the horticultural oil is less diluted than it is when its used after plants have leafed out. The importance of the horticultural oil for the organic rose gardener is that it suffocates many pest and their eggs before they become active as the weather warms up. It’s good as a control for aphids, spider mites, scale, sawfly, and thrips. The dormant oil should be applied all over the canes of the roses. The easiest time to do it is after pruning because all the unnecessary wood has been removed; but, if you will not complete your rose pruning until the leaves have already begun to emerge, do it now. The only brand that I know of is Bonide All Seasons Horticultural & Dormant Spray Oil.”
Heirloom Gardener 
This is a great tip for me ! I haven’t heard of the oil being used on roses .. it makes good sense .. and I am going to try and get that done. Thanks ! Joy
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A very good idea but I’m too late! Ours are all in leaf already. Thank you though, I will see if I can either find some or make it up next year. I’m afraid I do absolutely nothing in terms of spraying the roses – I rely on beneficial birds and insects to help out, and healthy plants fighting off problems.
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We are getting ready to spray our roses and are wondering how to keep the water and oil mixed prior to spraying. What do you use to agitate these two?
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Anonymous,
I just mix it right before I use it. I hope that helps.
-Heirloom Gardener
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Wow, there is a lot of helpful information in this post!
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Can I still use the remaining diluted oil I mixed last year or does it lose effectiveness.
Thank you for your help.
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