How interesting - I had never heard of that! However, I take calcium to avoid leg cramps at night, so it sounds like it is very useful for many things!

Jackie

I am going to repeat the information here so maybe Google will cache it. The other thread is not cached.

Extra calcium has been shown to reduce botrytis petal blight and balling in greenhouse roses and cut flowers. It also extends life of cut flowers. Spray budding stems, buds, and flowers once or twice a week when a flush is coming in cool weather with a chance of rain. If you have Safer's soap or Dr. Bronner's, use this instead of dish soap, as it contains potassium instead of harmful sodium. These solutions could be used in place of water in a fungicide spray if you are spraying that. The extra dish soap may not be needed--try and see if it sticks without.

Gypsum (calcium sulfate)--

I think this material should be quite safe for plants. Put 1 TB gypsum in a gallon of water and let sit for a week. It is very slow to dissolve, and heat does not help it dissolve. Pour off carefully to leave sediment behind. Spray with this concentration and 1-2 TSP of dish soap as a spreader-sticker. For vase solution, dilute with 2-3 parts of water and omit the dish soap.

Calcium chloride (road salt, ice melter)--

Careful, as this is more likely to damage foliage. It dissolves easily. Use 1 slightly rounded TSP per gallon as a spray solution with 1 TSP dish soap as a spreader-sticker. For vase solution, dilute with 2-3 parts water and don't use dish soap. Do not add bleach to the vase solution, as you've already added chlorine.

Calcium nitrate (fertilizer sold at farm stores)--

Use 2 TSP/gal as spray solution with 1-2 TSP dish soap. It may dissolve cleanly or may leave an insoluble sediment.

-------I sprayed with ice melter (impure calcium chloride) on Saturday at 1 tsp/gal. There is no sign of phytotoxicity so far.

The Mayflower is an Austin rose that balls an awful lot in my garden. Has anyone tried a calcium spray with this rose? Any opinions on the matter? It's a bit late in the year to test for myself.

I love the info. you provide, Michaelg - what would we do without you? Many thanks.

My soil has plenty of calcium, my water is high in calcium. It rained all day yesterday, our night temp. is low 40's. My roses are not balling whatsoever. Now I know why.

After 5 days, I can say that calcium chloride ice melter at 1 TSP did not burn foliage during cool weather. You could also try 1/8 TSP/Quart as a vase solution.

StrawberryHill, it may take a few days for botrytis symptoms to develop. Check again on Tuesday.

It rained all night last night, Sat (10-15). Now is 10:30 am, temp. outside is 42 degrees. Mary Magdalene rose is opening up outside. Room temp. when I woke up was 63, with Radio Times rose opened wide in a vase.

May be it's not cold enough yet for balling? Or do the roses have to be on a bush for balling? I have Radio Times many times in a vase, at low 60's room temp., and it still opened. I like to grow Brother Cadfael rose for next year, but the balling issue is holding me back.

Sometimes brown or moldy spots appear on a cut rose after cutting; it's a problem in the florist rose trade.

The optimum temperature according to Compendium of Rose Diseases is 15 C, so say 55-65 F with free moisture and high humidity.

Michaelg, thanks for the info - I appreciate your help. I see some minor brown spots on 2 outer petals of Radio Times. I can't tell if that's from the heavy rain and high wind we get. That cut rose was beating against the house in the rain.

It was 30-40 mph wind, I gave up on raking leaves. The rest of the petals are perfect. I checked on botrytis on past forums: Mayflower and Brother Cadfael are both notorious. So are New Zealand and Tiffany. I didn't see balling on New Zealand at the rose park, but both New Zealand and Double Delight are mighty ugly with spotty colors in cool and wet weather. Someone in a past rose forum got rid of New Zealand both for ugliness in cool weather and lack of scent.

I have just picked Mary Magadlene for the vase at 43 degree temp. outdoor. The petal against the house is bruised, with a minor brown spot - the rest are perfect. Radio Times' 2 petals are bruised from wind and rain beating against the house. Here's the picture:

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