Flashing the paper is not difficult and as mentioned making a sheet as a test strip of the paper you intend to use would be necessary. It should be completely processed, washed and dry and kept as a reference. If there is no detail in the negative flashing will not produce any. I don't know what equipment or what your metering technique is but if available a spot meter is helpful. Also there is a filter type viewer (sort of a brownish color) that will eliminate colors so you can see the relative values of the scene and decide whither or not you want a filter. If it was a bald sky the only way to add them would be to build a library of cloud negatives and print them in ala Jerry Ueslmann. If the grass was dry and somewhat yellow that would cause it to be "lighter" in the print. Learning to split print with contrast filters or a variable contrast light source can help in many difficult situations.

A frequent APUG contributor Ralph Lambert has written an excellent reference book "Beyond Monochrome" that would be worthwhile getting.

http://www.jeffreyglasser.com/
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