Simple Solutions

You want to use non-pesticides in your herbal garden since you will be eating and using these herbs to heal yourself naturally.

There are several ways you can keep bad insect away from your herb garden without resorting to harmful chemicals.

Many herbs are natural insect repellants such as Tansy that helps keep flying insects away.

Do some research in books and online or call your local greenhouse to see what herbs in your area help keep insects away and plant these around the edge of your garden with a couple planted through out the garden.

Tansy, Rue, Wormwood, Lavender and Elder are the most common herbs that will keep insects away from your garden.

You want to be sure you have a good place for the beneficial insects to come and live in your garden.

Provide a water source in your garden to attract these insects.

Water Source:

Use a bottom to a plant container (the round kind or even another kinds) and fill it with stones, small amounts of sand and water. Be sure to change the water often.

Home Remedies:

Use baking soda to treat fungal problems like black spot and powdery mildew. Mix 2 tsp of soda to 8 cups of water and drench the plants at the first sign of problems.
Snails and slugs love beer, that's right its not just our favorite beverage lol, so place a small container that a slug or snail can crawl into and they will drown while trying to get a drink. This does work when I lived in Washington State our apartment was below ground level so our balcony was about 4 feet below the ground, we used to get slugs all the time it was gross! So I placed a small pie tin filled with beer on the ground level just above our balcony and every morning the tin was filled with slugs. GROSS but very effective.
Snails and slugs also won't crawl over sand or sawdust so sprinkle this around your herb garden to prevent them from even entering.
Sprinkle plants (seedlings) from root maggots by sprinkling around the bottom of the plants: chili powder, pepper, ginger or paprika. This works to also keep animals out of your garden.
Spray your plants with a soapy water mixture and cooking oil. Mix 1 cup of each soapy water and cooking oil. Combine 2 tsp of the solution with 1 cup wwater and spray on plants.