Hi Kelby: I would get $1 distilled water, and 50 cents of RED cabbage. Boil chopped RED cabbage in distilled water, drain off the cabbage, then pour the hot juice over a sample of soil, taken near the root of your rose. Wait for at least 30 minutes before observe the color change.

Compare the color change of the juice of the soil to another sample of one drop of vinegar in red cabbage juice. The vinegar should be bright pink. If your soil is deep pink, then it's very acidic. If your soil is clear, then it's neutral.

I see the lowest leaves being yellowish: severe potassium deficiency, most often in acidic soil. I also see nitrogen deficiency in the surrounding grass, most often in acidic soil. If your soil is sticky clay, then magnesium is plenty .. lime pellets will neutralize the acid. Lime pellets is sold $6 per lb. at local stores.

If your soil is sandy, then magnesium is most often deficient, then dolomitic lime (has both magnesium and calcium) will neutralize the acid.

Rugosa HATES chemical fertilizer. If chemical fertilizer like MiracleGro is used, then Rugosa drops off all the leaves.

My Austin Eglantyne has Rugosa heritage .. It dropped all the leaves when I gave it chemical fertilizer. Finally I gave it blood meal, then it was healthy. I would correct the pH of the soil first, through lime pellets (if acidic clay), or dolomitic lime (if acidic sandy soil). Both are sold at Kelp4Less, free shipping.

Good luck with your Rugosa. My brother has acidic clay in MI, and addition of lime made a big improvement in his crops.

Here is a link that might be useful: Kelp4Less Hydrated Lime and Dolomitic Lime

Below is a quote from Spring Valley Roses:

"One of the most important thing to know about Rugosa roses is, in our experience, they can't tolerate liquid chemical fertilizers. Rugosas will often drop all their leaves (defoliate) if you spray or feed them with liquid chemical fertilizers, like Miracle Gro. We get lots of calls from people who tell us that their Rugosa's leaves turned yellow and then fell off. Our first question always is, "Did you give them a liquid chemical fertilizer?" The answer so far has always been "yes." Then we tell them not to ever do that again, and that their rose will recover. Even with organic liquid fertilizers, Rugosas can be sensitive to a sudden dose of nitrogen, especially when applied to dry soil. So, always, always make sure you apply liquid fertilizers to wet soil, not dry soil. Water first, then fertilize."

Here is a link that might be useful: Spring Valley Roses on Rugosa

Hi Kelby: See excerpt from below link:

"Beach Rose (Rosa rugosa)
Alternate common name: Sea Rose, Salt-spray Rose.
Appearance: Dark green bushes from 3 to 6 feet tall. Blooms range in color from white to pink to red; very fragrant when blooming.
Habitat: Coastal sand dunes, salt marshes, rocky shores, and roadsides."

Rugosa roses are known as "beach roses" for its affinity to sand. I have heavy clay, and Rugosa heritage like Eglantyne hates it. Even when I brought the pH to slightly acidic, the root can't expand in heavy clay. So I fixed the hole with 1 bag of coarse sand, then it bloomed well.

My neighbor put coarse sand at the bottom of the planting hole. Her roses are twice bigger than mine. People use sand to root roses. The rain passes through the clay from above, and washes down nutrients to the fluffy sand below. I learn the trick of keeping the bottom of the hole fluffy, and keep alkaline clay on top for fungal prevention.

Rugosa doesn't need much fertilizer, and clay is already fertile, no need to add fertilizer.

Here is a link that might be useful: Beach Rose, or Rugosa Rose