•First off it depends on what kind of herbs you're growing, where you're growing them and how you plan on using them. Simple herbs and spices for cooking are all fine and dandy but I think we all know, considering this website I don't think most of us here use herbs just for cooking. Herbal gardens aren't something like normal flower gardens. Depending on each herb almost like with certain flowers will have its own need however herbs aren't used just to look pretty, what that plant provides depends on how you treat it.
Chemically Dealing with pests is something you shouldn't really do with herbs you plan to use especially if you're growing some sort of sacred herb. A natural way of taking care of certain pests is a population of lady bugs... they eat all the aphids which eat you plants. Of course you may have some other "pests", I for one raise chickens. 1 good little solution to keep them out of your garden (and this is a trick I recently learned) is spices. Get you a nice blend of cayenne pepper, peperica, etc. and sprinkle them all around your garden not in the plants but around the garden, the strong smell repels them and not only that but upon the chicken actually entering the "line of fire" the spices on the ground will cause a burning sensation upon their feet which will cause them to flee (it won't hurt them however). Weeds, if you wish to deal with those you have to do it manually unless you want to pour chemicals on your herbs which you probably shouldn't do if you plan on using them. Also, guardians of the garden are also nice, and by guardians I usually mean like a cat. They eat mice that like to run along in your garden, and maybe some garter snakes for insects.
Growing and Nourishment~
Each plant has its own particular needs but here are some tricks that you can utilize to help your herbs. One trick that you might not like is poop. Not just any poop, goat poop. One of the best natural ways to nourish the earth comes from the butt of a goat, who woulda thunk it. Of course nourishing the earth isn't enough to tend to plants, some people who maybe used to growing know this but to the novice black thumb maybe not. Get rid of yellow or brown leaves, leaves with brown on them must be gettin rid of, these leaves take a lot of oxygen away from the plant so it would be best to just cut it off the plant and maybe bury it by the roots to let it naturally decompose.
Harvesting and Containment~
First off if you're harvest roots be very careful with what you're about to pull from the ground and not only that but also make sure you wash the roots upon harvesting them especially if you used sone type of fertilizer (common knowledge) you want to get the best from the roots so you want to not completely uproot the plant but also not completely miss out on whatever you can get. Harvesting anything else should be fairly easy as in for containment... usually I like to use candles believe it or not, those little jars with lids that certain candles are in? Once the wick is gone I cut out the remainder of the wax out and wash the jar, then I reuse them to hold my herbs.
Grow some spearmint, very easy to grow but have some very aggressive roots so try and just grow that in a very large pot, mint is a very excellent remedy to combat stomach aches
Valerian root, I think everyone should know the MANY uses of valerian root, brewing a tea from its roots can ease anxiety and depression and not only that but also can put you to sleep, or someone else. Simply harvest the roots wash them and hang them up to dry then use a mortar and pestle to crush them into a fine powder, put the powder in a tiny tea bag sized, well bag, as well as other things (some people also put in rosemary or Passion flower etc.) and then stitch the bag (preferably some kind of thin cloth) and you got your own valerian root tea or you can just make your own blend of herbs with the valerian root and out however much you need in a tea pot, add in the boiling water, let it steep, then pour it in a cup through a filter.
Aloe Vera, every one knows this can be used for burns, so this is definitely something to put in an herbal garden for someone as clumsy as me..
Lavender, OMG LAVENDER YESS, you can put this in a bundle with sage as well as other things and BABY GIRL YOURE IN BUSINESS. You got yourself your own smudging stick. Just trust me on this one I won't go into detail but the aromatherapy is to die for.
Basil, take some of this and put it in the water inside of vases where you keep your flowers, keeps it from getting stagnant.
I don't have anymore tips that work with all plants, each plant has its own needs, just like tending to any other living creature and or entity, so good luck to all of those out there who plan on brewing their own concoctions and creating their own remedies, I for one am definitely for all types of alternative medicines, so I give anyone a big green thumbs up for whoever plans to walk that path.