Creating a flourishing herb garden takes more than just sowing the seeds and letting them grow. Therefore, it is important to have some basic herb garden plans before you even put the seeds in the ground.
Because herbs can grow well in poor conditions, it is easy for them to overgrow. Lavender and yarrow can grow like wildfire over large areas. Even chives can proliferate quickly. Be sure you have enough space in your pot or garden for the plants you wish to grow.
You should be fine as long as your herb garden plans include about 1 foot of room between major areas. Chives are an example of an herb that grow well in a bunch. However the roots need a sufficient amount of nutrients and water and anything planted near them will have to compete for those.
Soil is a must for growing herbs, although extensive soil preparation is unnecessary when learning how to build an herb garden. If you intend to grow a wide array of herbs, try to use a good compost or combination of sandy loam and clay. Herbs do well in soil that is rocky and somewhat dry because of their Mediterranean roots. Their background of growing in areas with enough drainage makes this a must. Make sure the soil stays moist as herbs do need some water, but do not drown them in soaking wet soil.
To name a few, Lavender and Sage will thrive without you having to water them. Rainfall seems to be enough for them. Peppermint will need additional watering which can be supplied by an automatic drip system.
Landscape fabric is a great way to keep weeds from growing in your garden, ruining the beauty of your garden and choking out your precious herbs. Digging up weeds later can be tiring and frustrating, while using herbicides might kill your herbs since they have a similar makeup. You also do not want to spray poison on your future food supply.
Most herbs repel insects, but you probably want to consider a 'trap crop' in your herb garden plans that you can sacrifice for the preservation of the others. Dill makes a decent one, as it attracts bugs away from your other plants such as tomatoes. You can use a minimal amount of insecticide to save your dill crop, but use the smallest amount that you can still get away with.
The final thing to consider when learning how to build an herb garden is to know when to plant your herbs. Some thrive at different times of the season, some should be planted every 4 weeks. Knowing when to plant will insure a great crop.