Prevention is always better than a cure, but if your boots are a bit mouldy from storage, they can be salvaged. Depending on the growth, you may first need to use some leather wipes to wipe away excess mould, then follow up with a high quality and good lathering of leather conditioner. Allowing the conditioner to soak in overnight is best. Wipe away excess conditioner, and buff the area. Follow this with a water and stain protector to seal in moisture and keep dirt, grime and excess moisture away. Before adding the water and stain protector, you may wish to apply some pigment back in to the shoes with a good quality shoe polish (in your shoe's colour of course).
Remember leather is a real protein, just like your skin or hair. Therefore, your shoes and bags need conditioning and waterproofing just like your hair and skin.
Never store leather shoes or bags in plastic
Always store them in a dry, dark, cool place, and in a cotton bag which allows the leather to breathe. Shoe boxes are also a good option.
Mould likes environments that are humid and wet for optimal growth.
To prevent mould – give you shoes a good clean with a leather conditioner at the end of the season, so they are nourished ahead of being stored away. Follow this treatment with water and stain protector.