It's probably a little low but I wouldn't panic. You might check to see what the natural pH of your soil outside of the rose bed is and if it is much higher, you might start to think about your fertilizing practices. Organic matter, including wood mulches, tends to make a soil slightly alkaline. Over-fertilizing with ammonium sulfate or urea tends to acidify the soil. A heavy application of lime sulfur fungicide can also lower the soil pH.

Yes, at that level a lot of certain nutrients in the soil become unavailable to the plant. 6.5 is generally considered the best PE for most roses, although I know some rootstocks like multiflora will do well in a higher PE. You will need to add some lime to the soil, how much, I am not sure. You can contact your local agricultural extention, they should be able to make some recommendations, as well as do a soil test.

ameri2nal-thanks. I actually have the soil test results along with recommendations BUT i'm a fairly laid back (lazy) gardener and liming has always seemed to be such an aggressive intervention. I guess i'm asking to see if other forumers have success rose gardening in a similar pH.

Mike Rivers-i was hoping you were out there today :) Alas the pH is sampled from completely native soil so i take no credit or culpability for it. I am finally emerging from a prolonged state of analysis paralysis and preparing a long, winding bed. My plan is to loosen the existing clay, top dress with bonemeal, then compost, then wood mulch. I can till in some lime if it would make a difference in the appearance/bloom of the roses. Do you think it would be worth it?

As far as rootstock i so far have either own root or the good Dr.

Liming is a routine maintenance operation for most acid-soil gardeners; grass doesn't like extremely acid soil either. You should not need to lime repeatedly; simply add it at the recommended rate & retest in a few months to see how you're doing. Once I "knew" my soil at the farm, I measured off the new beds & did the liming when I made them then let them mellow a few months before the roses were put in. Worked well, & despite acid rain (this was Ohio) I never did need to re-lime.

i think they say the lime takes a little while to be effective, but i think it would also be the easiest thing to do. I'd just fill the spreader, spread and be finished in about an hour per acre maybe.

I agree that lime would probably help and raising soil pH with lime is pretty routine stuff. Ideally, you should get a soil test but barring that, 6 pounds (that's just 3 cups) of Agricultural lime (Ag Lime) spread evenly over 100 sq ft of soil should raise the pH of a typical loam soil about one unit. You want to spread the lime as evenly as possible and work it into the soil as deeply and as thoroughly as possible. It will probably take most of the summer to do the job and the usual recommendation from extension services is to not try to change the soil pH by more than one unit per year.

5.4 is pretty low. And not surprising either, here the soil is often that low too. Heavy rainfall areas tend to have acidic soil.

Get some prilled lime, it's in little pellets instead of a fine powder, much easier to work with. Add some to the planting holes so it's down at the roots. Spread some over the garden in the winter. Check the pH again every year to see if you need to do it again, but I'd only do it once a year at most. Many rose gardeners here just routinely add lime once a year or two. It's not particularly invasive or laborious in my opinion.

You don't need to obsess over the exact pH, but really, 5.4 is awfully low.

The native soil here varies between 5.4 and 5.7. Let's just say that hydrangeas need no aluminum sulphate here to be blue. It isn't soil deficiencies to worry about (there aren't many). One problem can be the extra solubility of things like aluminum and copper. Al isn't listed as a nutrient on any soils test I've seen, but in very acid soils, it is ultra-available for uptake by plants. When I did tissue tests on my roses to diagnose issues, Aluminum and copper were present in very very high levels.

We use oyster shell lime locally to buffer pH and to offset the mega-high magnesium content of most California coastal soils with some calcium. In fact, every fert I use, if I can, I use one with a calcium component. Gypsum is my friend.

The usual soils test, if the test knows its an existing garden, have relatively simple, minor amendments for existing landscapes. There isn't that much you can do. What I've read about liming locally indicates it changes the pH of about the top 4 inches of soil...not all that impressive in my book. So when I plant or install new beds, I follow the soils scientist's recommendations to the letter. But with existing beds, all I do is a little maintenance every now and again if I see a problem.