I don't know where you are in the US, there are differences in zone 6 across the country.

If you are on the east coast, I recommend returning the plants and replacing with disease resistant varieties, which won't be hybrid teas. And, you probably won't find many available at your local store, other than Knock Out (and children/siblings), Home Run, Pink Home Run, White Out. You have a wider selection by online ordering, but most vendors have closed for the season (there are a few that are still shipping).

You will get an extrodinarily long response that will say that you can stop black spot using organic means. In 21 years of rose growing in NJ, I haven't found one.

Powdery mildew is usually seasonal. But, it can be controlled using a 10% milk solution (1 part milk to 9 parts water), or the baking soda solution, but note that you will have to reapply if it rains. An organic soap would be Dr. Bronner's, and I think Mrs. Meyer's Clean Day is mostly organic.

You are welcome to try any remedy that you find, and please report back if you are successful.

Hi Elizabethsarah: Most likely the hybrid teas you bought are grafted on Dr. Huey. Dr. Huey likes dry weather and alkaline soil like CA. I saw grafted-roses break out in BS in acidic potting soil when it rains at Home Depot.

Per your question of baking soda, Green Cure (potassium bicarbonate) works much better than baking soda against mildew. Per your question of soap in the spray, one person did that hot weather and it burnt her roses. The product "Green Cure" is guaranteed not to burn.

It's best to return those Hybrid teas to the stores. The bud-union where they were grafted could be damaged by dryness in storage. If you have acidic soil, grafted-on-Dr. Huey will misbehave. My zone 5a winter zapped the bud-union. In my last house of acidic clay, I dug up black spotted grafted-hybrid teas and found the roots shrank in wet & acidic clay.

Own-roots last MUCH LONGER than grafted. Own-roots can spread out, versus water's moving up is restricted by the bud-union in grafted roses. You post just the right time, Roses Unlimited in North Carolina will have a sale 1/2 off, it was only $8 for BIG own-roots (gallon-size) last June, came with blooms even.

If you google "Roses Unlimited" and check on them 1st week through 2nd week of June, they will list the sale. It's sold out fast, best to check everyday. Click on the link below to see how disease-resistant the newly-bred own-roots are. Many people across the country contribute to that thread, "Your most tough, healthy, no-spray roses?" Hopefully you'll find the right types for your soil and climate.

It's good to check your soil pH, some own-roots like alkaline soil like Romanticas & Robert Neil Rippetoe's and Kim Rupert-bred roses. Others like acidic soil like Rugosas and most Austin roses.

All my 52+ own-roots stay clean even with my 40 inches of rain. It's very humid here now... they are still clean with no-spraying. My present soil is heavy clay with limestone, pH 7.7. Calcium is important to strengthen cell wall and disease-prevention, just like potassium. It's plenty in my limestone soil when rain water (pH 5.6) releases that from my clay.... but deficient in potting soil, or soil elsewhere in the country.

I posted a thread on what type of calcium to add to your soil, depending the pH of your soil in the English Roses Forum. If you google, "English Roses forum", you'll see that post on gypsum in the Soil section under my alias Straw.

Below is a bouquet of roses with disease-resistant roses bought from Roses Unlimited. I bought during June sale for $10 per gallon: Deep Purple, Francis Blaise (pink), Honey Bouquet (yellow), Pink Peace (dark pink). They are clean all year, even in late fall.

Here is a link that might be useful: Your most healthy and no-spray roses?

This post was edited by Strawberryhill on Thu, May 30, 13 at 18:55

Hi Elizabeth: It's good to get your soil tested before growing roses. EarthCo. test your soil for $20: the pH, calcium, magnesium, potassium, phosphorus, and organic matter. They also do a salt test for $12.

I think the salt test is the most important. In my last house of acidic clay, I dumped too much Bayer fertilizer 3 in 1 and zapped the root, plus killed all insects. All chemical fertilizers have salt. Salt drives down potassium and calcium ... both needed to fight diseases.

Last year I used acid fertilizer for my alkaline clay, NPK 10-5-4. Chemical nitrogen is high in salt, so my roses came down with mildew early summer. This year I use zero chemicals, but fertilized last fall organically. So far none of the roses have mildew. Two years ago I didn't use any chemical fertilizers, only alfala meal and horse manure, and had zero mildew for the entire year.

The salt in chemical fertilizer can really hurt roses. Most folks use more than needed. Jeanie in PNW (rainy climate) reported that the rose park there uses animal manure only once in spring, and nothing else afterwards. NPK of cow manure are approximately 0.5-0.5-0.5, very mild. Plants are healthier with low-dose, slow-released organic fertilizer.

Check out the mildew on my Austin roses fertilized with acid fertilizer NPK 10-5-4. One time I put too much acid on my roses, and the leaves become thinner. Acidic soil are most lacking in calcium and potassium, needed to make leaves thick and strong to fight against fungal invasion.

Roses Unlimited has large selection of disease-resistant Kordes Rose. I have two Kordes roses (Deep Purple and Coral Flower Carpet), they have the thickest leaves ever, always clean here. If roses are prone to disease, it's best to check the soil: either too much salt from fertilizer, or lacking in calcium, potassium, and trace elements for strong plant tissue.

This post was edited by Strawberryhill on Thu, May 30, 13 at 19:02