by Sue Tiffany
Most of us in the Pacific Northwest live on glacial till and it tends to be acidic. Being newly returned to growing roses, I had my soil tested at no cost through King County Conservation District and all my soil was VERY acidic. The military has an expression: “When in doubt, there is no doubt.” To me, that means check first. Be careful. Believe all things could be wrong. Before doing anything, ask your county conservation district if they do free soil testing. If you test it yourself, for the sake of your roses, make sure your meter is accurate.
GETTING THE RIGHT pH FOR YOUR ROSES: THOUGHT #1…
Roses like a pH of 6.0 to 6.8 and adding too much of anything could have a disastrous effect. If necessary, the quickest way to lower pH is to add aluminum sulfate. Just be careful. A slower, but perhaps more controllable way to do it is to add sulfur as it is slower acting. A third method is to add sulfur-coated urea (the more expensive option), but if you plan to fertilize anyway, you can purchase a fertilizer with this in it. Just think about what you want to do and how quickly you feel it needs to be done. In the long run, adding organic matter, like compost, composted manure and acidic mulches (e.g. pine needles) can gradually lower your soil pH over time. As organic matter decomposes, bacteria and other microbes grow and feed upon it, creating acidic by-products in the process.
GETTING THE RIGHT pH FOR YOUR ROSES: THOUGHT #2…
Once again: Roses like a pH of 6.0 to 6.8 and adding too much of anything could have a disastrous effect
IMPORTANT: pH is the result of the elements in our soil, not the cause. SOME THINGS ARE SO IMPORTANT, THEY ARE WORTH REPEATING: pH is the result of the elements in our soil, not the cause.
The ideal line for nutrients for roses in the graph below shows that there is a narrow band where ALL the nutrients our roses need are available. That is why pH is so important. If we want our roses to have all the nutrient they need, we need to balance the pH between 6.0 and 6.8.
GETTING THE RIGHT pH FOR YOUR ROSES: THOUGHT #3…
If pH is the result of the elements in our soil, should we add limestone to our soil on a yearly basis? Of course not! This is where soil testing is so important! It’s even worth paying for it as soil is a living organism that is far too complex for me to explain.
SIGNS OF PROBLEMS:
Yellow leaves are always a worry for me because they can mean too many things. Is there too much water? Not enough water? Not enough iron? The list of causes of yellow, yellowing or yellow spots on your leaves is too long.
There are solutions. There are 3000 conservation districts in the United States.
- STEP 1: Have your soil tested.
- STEP 2: Having a meter that reads moisture.
Without a moisture meter, I use my trusty first finger, poke it into the soil and check for moisture the old fashioned way. If my finger comes out dry, I know my roses need more water.
Seeing my roses happy is worth the extra effort.