tin cans

The geraniums we grew last year in 5 litre paint tins were noticeably superior to those grown in plastic or terra cotta pots. I wonder whether this is to do with being metal or the fact that they are straight sided and present less area at the top for evaporation. Anyone got any thoughts?
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stuart snipped-for-privacy@ntlworld.com wrote in

Possibly the extra heat conducted by the metal stimulated extra root growth.
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David J. Bockman, Fairfax, VA (USDA Hardiness Zone 7)
email: snipped-for-privacy@beyondgardening.com
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less watering, so I'm sure it's something to do with moisture retention. I'm going to try a straight sided plastic container this year to see if it's the shape that makes the difference.
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