Bordeaux mix is one of the oldest – and still used- horticultural sprays on the market and here’s what you need to know.
What Does It Control
It controls a wide variety of bacterial and fungal problems. Mostly used on fruit trees, some vine fruits, and a few ornamentals. See the cautions about using it on ornamentals.
What’s It Made From
There are three main ingredients in Bordeaux mix: copper-sulfate, hydrated lime and water. That’s it.
And many of the modern sprays have simply eliminated the lime and are using only the copper.
We usually refer to the proportions in this order: copper, lime, water. So a mix of 10-10-100 refers to 10 parts of copper sulfate, 10 parts of hydrated lime and 100 parts of water. You can often purchase these ingredients separately from garden centers or purchase it ready made (far easier and safer)
Note the copper has to be finely-ground copper sulfate (bluestone). If you purchase garden-grade copper sulfate, it will not dissolve as easily and/or take a very long time to do so. Store extra in a very dry spot. If you get this material wet/damp it will become lumpy and difficult to dissolve and work with.
The lime can be either hydrated or slaked lime but NOT regular garden lime.
Caution: Working with hydrated lime and copper sulfate can be dangerous.
This is an extremely caustic material that can cause skin and eye damage (seriously – don’t mess with this stuff).
Complete safety covering is highly recommended and children should not be anywhere near the process.
How to Make Your Own
Use plastic buckets!
Mix 1 pound of fresh hydrated lime into 1 gallon of water. Let it stand for approximately 2-hours before you use it. You can also store this basic lime mix almost indefinitely if you have a lid on the bucket. (This just saves time the next time you want to make some)
In a separate bucket, mix 1 pound of copper sulfate with one gallon of water. Dissolve thoroughly and allow this to sit. This too can be stored in a glass container indefinitely.
You know have the two separate components.
Note you only mix them when you want to use them and you do not store the mixed material.
To Mix Them
Take another plastic bucket.
Put 2 gallons of clear water in it. Stir up your lime so all the lime is in suspension. Add 1 quart of lime to the 2 gallons of water and start stirring. ( A wood stirring stick is best)
To this lime-mix, add 1 quart of copper sulfate and continue stirring for several minutes or until the components are fully mixed.
Immediately pour into a sprayer and apply to your garden plants.