Washing and cleaning herbs well enough for making remedies or drying them for later use can be a bit daunting, however it's not difficult if you follow the steps below.
After you've harvested your herbs or pulled them up when weeding the garden as I have done with stinging nettle, check them over for insects, bird droppings, and damaged parts. Shake or brush off any insects, discard the parts with bird droppings as they are too hard to clean, discard any damaged parts, and gently shake off as much dirt as possible.
Fill a laundry tub or kitchen sink with plenty of water and dunk the herbs so they are fully immersed. Gently swirl them around making sure to remove all the dirt from the aerial parts and roots.
Lift the herb material from the water, shake gently then place it in a salad spinner. Spin both ways several times to remove as much water as possible.
Carefully tip the herb onto a clean, dry tea towel and spread out to dry. If drying stinging nettle use thick gloves or tongs to handle it.
Allow herbs to dry off for a few hours then put onto another clean, dry tea towel and leave until most of the moisture has evapourated. If you want to make a fresh plant remedy then use the herb immediately and if you want to preserve the herb by drying tie into bunches and hang in a bright airy place or dry in a dehydrator.
Note: When washing fresh herbs for culinary use, spinning them in a salad spinner prior to chopping them is all you need to do before adding them to salads or the meal you're cooking.