After gardening for a few hours, your hands and nails are likely stained and dried out. Wash off the surface dirt with a mild soap, then friction generously with olive oil. Make sure oil goes under the nails too. The dirt lodged more deeply will come off. Then clean around and under the nails. Then friction with freshly squeezed lemon or lime juice and give a quick rub to your nails with Vit. E. Your hands will get back their vitality.
If you have blisters, there's use a lavender, calendula and yarrow maceration. For details, see article on macerations in previous entry.