Hi Smdmt: My mother-in-law lives in Colorado Springs ... it's dry & alkaline. U. of Colorado Extension specified that manure has salt, should be used only once a year for dry climate. I agree, in my Chicagoland of 23" snow and 40" rain, I fertilized my roses in late fall (right before Thanksgiving), then once more before spring rain.

During the summer I used alfalfa hay as mulch, it was very effective in moisture retention, plus supplying nitrogen at NPK 2.5-1-2.

Since Colorado is mostly dry & alkaline soil, leaves, compost, or alfalfa hay would be most effective to retain moisture. Piling up to a heap of 4 inch. would be great for the winter. I save old plastic container, cut into a ring to put around young roses, then pile organics inside that ring. The pile is open to let rain & snow in.

I don't get black spots with alfalfa hay on top (neutral pH) .... but I get black spots with alfalfa pellets and meal, which break down into sticky & wet & acidic layer, perfect for fungal growth. Here's my rating for black spots & mildew with different toppings in my garden:

1) Encap compost (cow-manure & leaves) is worst for mildew .. OK for black spots. Milorganite (with 4% iron, a sewage sludge, NPK 5-2-0) promotes fungal growth with its salt-content and iron. I get both mildew and black spots with Milorganite.

2) Bagged cow-manure is absolutely awful for blackspots. In contrast, horse manure with lime kept my roses clean for the past 3 years.

3) Wet & acidic leaves like maple leaves encourage black spots. Dry & fresh & neutral pH wood-chips is OK ... I don't see any black spots when I mixed those into my soil.

4) My best result to suppress fungal diseases is either horse manure, or alfalfa hay. Alfalfa hay holds moisture better than horse manure, plus zero salt, so alfalfa hay would be best for dry climate. Roses die through the winter not so much from the cold, but from the drying-wind.

Below picture was taken yesterday Sept. 30, I mulched Sweet Promise hybrid with alfalfa hay. It's sold for $8 per large bale at the feed store. One bale can easily mulch at least 10 roses.

This post was edited by Strawberryhill on Wed, Oct 1, 14 at 16:13